OMG - This is Totally True

Countdown Continues...

Honors Physics went over their Bernoulli’s equation and gas law problems and then got clobbered with a set of mixed review items. We’ll go over those in class tomorrow for our pre-vacation fun activity.

Physical Science B discussed calorimetry and worked a couple of calorimetry problems as a class. The lab that we will conduct when we return will allow you to use a rudimentary calorimeter and compare heat gained and heat lost by materials in a relatively closed system. Tomorrow, we’ll address your MCAS open response practice for our pre-vacation fun activity.

Physical Science E conducted a lab investigation into heat transfer. The first investigation allowed you to see that the amount of heat lost by one substance equals the amount of heat gained by a second substance. Since both substances were water, even the rates of gain and loss were identical. The second activity let you measure the energy stored in candle wax. By using the coke-can-calorimeter, you were able to use temperature changes in water to track how much energy was being delivered by a burning candle. By massing the candle before and after the test, you could report how many Joules of heat energy each gram of wax contained. We’ll go over this lab and discuss your MCAS specific heat practice items for our pre-vacation fun activity.

Physics F discussed yesterday’s lab investigation and the chapter review questions concerning fluid pressure. Time was then allowed for test corrections, which are due tomorrow. We will further examine fluids in motion, specifically Bernoulli’s Principle in class tomorrow as our pre-vacation fun activity.

Physics G was introduced to fluids in motion. The types of flow were compared and how flowing fluids observe conservation of energy and mass was discussed. We spent time discussing examples of Bernoulli’s Principle and will continue with this tomorrow as our pre-vacation fun activity.

Homework

Honors Physics A: Chapter Review #34, 38, 48, 50, 60
Physical Science B: Complete MCAS open response practice
Physical Science E: Complete lab write up and MCAS specific heat practice
Physics F: Complete test corrections
Physics G: Chapter Review items #20-22

Countdown!

We just have to make it through Wednesday...hold on tight...

Honors Physics reviewed their Bernoulli’s equation problems and then launched into a discussion about gas laws. The three gas laws that we went over in 9th grade (Boyle’s, Charles’s and Gay-Lussac’s) all derive from the ideal gas law and are valid when the number of particles in the sample does not vary and one of the following – pressure, temperature, volume – remain constant. We won’t have an exam on this chapter until after we return from break, but we will start in on the next chapter (heat), since the first bit deals with heat and temperature, two concepts we touched on in this chapter already.

Physical Science B worked practice problems with specific heat. Remember to look to units to identify which piece of information a number represents and read problems carefully when working with temperature. Are you being asked to solve for initial temperature, final temperature or temperature change? We’ll go over this sheet in class tomorrow, so do your best to work out each item.

Physical Science B went over their specific heat homework and then received a set of specific heat problems/questions taken from prior MCAS exams. We will go over these on Wednesday, and also go over tomorrow’s lab. The activity that you will conduct tomorrow will allow you to apply the heat formula to two different situations – to assess heat gained and heat lost for two materials in a system and to calculate the amount of energy delivered by a fuel (candle wax).

Physics F had their opportunity to work through the pressure with depth lab and got the same results as the previous two groups – a tight linear relationship between pressure and depth that generated an equation that could predict pressure at any depth in that specific fluid. We will go over this lab tomorrow, so have it completed and ready to go.

Physics G discussed their lab activity, including how the equation of the line generated in class related to our work in the textbook. Time was then allowed for students to work on test corrections.

Homework

Honors Physics A: 9.3 and 9.4 Section Reviews and Practice 9E
Physical Science B: Complete specific heat worksheet
Physical Science E: Read lab sheet. Complete MCAS problems by Wednesday
Physics F: Complete lab write up
Physics F: Complete test corrections

Unfortunate, But True

Friday!

Honors Physics moved from static fluids to fluids in motion today. The discussion centered around both the continuity equation and Bernoulli’s equation, which are statements of conservation of mass and energy in fluids. Bernoulli’s Principle and the pressure-at-depth equation were examined as special cases derived from Bernoulli’s equation.

Physical Science B discussed the concept of specific heat and related this concept to real-life situations such as moderate coastal climates. We went over homework problems dealing with specific heat and will get a few more on Monday. These types of problems and questions involving specific heat always show up (usually more than once) on the MCAS exam, so make sure you have a good handle on this topic.

Physical Science E took time to examine the three methods of heat transfer. No matter the method of transference, heat always moves from high-temperature objects/areas to low-temperature objects/areas, but the type or presence of medium dictates how the energy is passed. How well the energy is passed or accepted is a factor of specific heat, which we will hit on Monday.

Physics F began a discussion of fluids in motion and examined both free and enclosed liquids and gases. We got around to comparing types of flow (laminar, turbulent), describing an ideal fluid (and why they don't really exist) and using Bernoulli's Principle to explain certain aspects of life such as why smoke goes up a chimney or how perfume atomizers function. On Monday, you will get to work on the pressure/depth lab, so remember to wear things that you don't mind accidentally getting wet.

Physics G explored pressure variations with depth in a fluid column. A very clean linear relationship was documented and the regression equation was used to make predictions about real-world water-pressure situations. The second of the extra lab questions threw the class into an uproar, but with prodding, subtle hints, and graceful artwork on the whiteboard, students were able to calculate the force on their bodies at the bottom of the Marianas Trench. Have these labs ready for Monday!

Homework

Honors Physics A: Practice 9D
Physical Science B: None
Physical Science E: Complete the Practice p. 434 #2, 3, 5, and the 13.2 Section Review #5 and 6
Physics F: Read lab sheet. Complete p.343 #10-15 and p.344 #20,21 by Tuesday
Physics G: Complete lab write up

Honors Physics conducted a lab investigation that examined the change in fluid pressure with depth. The gas pressure sensors were used to measure atmospheric pressure and then the pressure in a column of fresh water at greater and greater depths. The graph of the relationship was very nicely linear and, if you think about the equation for absolute pressure, that makes sense. The y-intercept is the pressure at 0 m depth or atmospheric pressure. Your y-values are pressure, your x-values are depth, the slope is the product of the fluid’s density and acceleration due to gravity (P = P_o + ρgh). This technique can also be used to assess the density of a fluid, if it is not convenient to measure in the lab. Luckily for everyone, the water was mostly contained in the experimental apparatus and no one left the classroom soaking wet. On a cold, windy day like today, that is a very good thing.

Physical Science B went over the multiple choice items of their MCAS review packet. People seemed to do moderately well, but make sure that you clear up any problems by MCAS time. Also, make sure to clear up any issues by midterm exam time. As I said in class, start gathering all the materials you need to study for the midterm exam. Gather you old tests, practice problems, notes packets…the exam is cumulative, meaning back to Day 1 and there is no opportunity for corrections or extra credit. The final is also cumulative, but you will have taken the MCAS prior to that, so the material should be somewhat fresh in your mind. Tomorrow – the ability of a substance to change temperature when it gains or loses heat energy: specific heat.

Physical Science E dove deeper into their discussion of heat energy with an overview of the temperature scales and the methods of heat transfer. We took time to discuss the recent lab activity and relate that to the information we covered in class. As we move into the area of specific heat, there is going to be another round of math, so make sure to have your calculators handy. The MCAS loves specific heat questions and problems, so we’ll make sure that you get plenty of practice.

Physics F and G continued on with their study of forces in fluids with an examination of fluid pressure. Collisions by fluid particles generate pressure in fluids and this pressure exerts forces on objects placed in fluids or filled with fluids. We took time to diagram and describe the function of hydraulic devices and began to explore the variations of fluid pressure with depth. Tomorrow, we will continue on with this discussion in F Block, but G block will conduct lab work on the topic.
Homework

Honors Physics A: Complete lab write up, including the two extra questions
Physical Science B: Complete MCAS open response by next Wednesday; have lab write up for tomorrow
Physical Science E: None
Physics F: None
Physics G: Read lab sheet

Let the Sunshine In!

Honors Physics spent the first part of the period going over their Chapter 8 exams. Although many people did well, some had a hard time with the material. Make sure to get with me to schedule a retest for next week and to come to me for any help you need with the concepts or problems. We then continued on with the topic of fluid pressure and how it varies with depth. Regardless of the fluid, as me move deeper in to the column, pressure is going to rise. The degree of rise depends on two things – the depth of descent and the identity of the fluid. The same goes for ascending in a fluid column, the pressure decreases based on magnitude of ascent and identity of fluid. Tomorrow’s lab will allow you to investigate this relationship with a column of water and examine the predictability of the relationship.

Physical Science B undertook an investigation for heat conduction/insulation. Heat is better retained in a bottle covered by a dry cotton or dry wool covered socks that if left uncovered. When you wet the cotton, however, the ability of the fabric to retain heat is severely diminished. Mom is right when she yells at you to get out of your wet clothes. The rate of heat loss in wet clothing can be very dangerous to humans, based on the surrounding air temperature. Dry clothes are a valuable piece of survival gear! Not all materials are as poor as cotton for retaining heat while wet. Wool retains heat quite well when wet, so despite being soggy, they are a better bet for hunters and sportsmen when they are out and about. The wait time for the investigation was spent working on MCAS review questions for work, energy, momentum and forces Make sure to finish up the MCAS review multiple-choice questions by tomorrow so that we can go over them in class.

Physical Science E went over their Chapter 12 exam and then moved into a discussion of heat and temperature. The concepts were defined and contrasted and then time was taken to examine the commonly-used temperature scales and how thermometers and thermostats function. We then began a discussion of heat transfer, using the lab as a springboard for the topic. Tomorrow, we will continue with this discussion, comparing and contrasting the methods of heat transfer.

Physics F and G began a discussion of forces in fluids. We put a specific definition to fluids and contrasted liquids and gases. We then turned attention to the concept of buoyant force and the role it plays in objects floating or sinking in a fluid. Density, despite what most people think, is not the player that makes things float or sink. Net force is what is responsible for the acceleration of an object, so it is the net force acting on an object in a fluid that determines whether it floats or sinks, the rate of descent and the depth to which something will float/sink in a fluid. Tomorrow, we will turn attention to fluid pressure and G Block will conduct a lab that focuses on how fluid pressure varies with depth.

Homework

Honors Physics A: Read over lab sheet
Physical Science B: Complete MCAS practice multiple choice items; have lab write up for Friday
Physical Science E: None
Physics F and G: Practice 9B #1, 2; Practice 9C #1 and the 9.2 Section Review #3, 4

Didn't Mythbusters Disprove This?

Back at the Salt Mine

I must say that the dogs enjoyed being chauffeured to daycare in the rented Town Car this morning. You would swear that they were royalty the way they were sitting and looking disdainfully at the passing traffic…

Honors Physics completed their overview of buoyancy and began a discussion of fluid pressure. We lost a number of folks due to the Peer Mentor training, so if you were one of them, make sure that you catch up on any missed notes. Tomorrow, we will continue on with pressure and this will lead us to Thursday’s lab, where students investigation the variation of fluid pressure with depth.

Physical Science B explored the methods and pattern of heat conduction in materials. Remember that heat always flows from objects with higher temperatures to objects with lower temperatures and that it is heat, as energy, that is passed, not temperature. We also discussed the three methods of heat transference – conduction, convection and radiation. Tomorrow’s lab will allow you to examine how insulators function to retard heat transfer and how different materials have different insulating properties.

Physical Science E went over their MCAS practice work. Seems like people were doing fairly well on the material and we’ll go over the last open response question tomorrow in class. Then, it is off to heat and temperature. We’ll examine the definition of temperature, the different temperature scales and how thermal expansion works in thermometers.

Physics F and G sat through a graded learning experience. Tomorrow – forces in fluids!

Homework

Honors Physics A: None (make sure yesterday’s classwork is complete, though)
Physical Science B: Read over lab sheet
Physical Science E: Look over MCAS practice for patterns – where are your strengths and weaknesses?
Physics F and G: 9.1 Section Review #1,2,5 and Chapter Review items #1-4, 6, 7

Christmas is the Cruelest Season

When your story begins "I walked outside to find a pool of swirling gasoline beneath my car," and then it goes downhill from there - you know its going to be a long day. But, I do get to drive an expensively-rented Lincoln Town Car to school tomorrow. For once, my car will be somewhat on par with my students' rides...

Thursday was a busy day of reviewing for exams, discussing buoyancy and investigating heat conduction. Physics F and G reviewed for their exam, which was postponed until tomorrow. Remember what we outlined on Thursday to focus your studies. Honors Physics entered the fluid world with a look at Archimedes' Principle and how to determine the buoyant force acting on an object placed in a fluid. We'll finish going over the homework for that material tomorrow and start yapping about fluid pressure. Physics B had an overview of temperature and thermal expansion, which was related to the function of thermometers. Tomorrow, we talk about heat transfer, which will dovetail with Wednesday's lab about conduction and insulation.

Physical Science E conducted a lab looking at the insulating properties of materials. Four identical root beer bottles filled with hot water served as our test platform. One was naked, one wore a dry wool sock, one sported a dry cotton sock and the last was burdened with a wet cotton sock. The data clearly showed that to retain heat, one should neither be naked nor wet. In truth, if we had repeated the test with a wet wool sock, students would have found that the heat loss was no where near as bad as for the wet cotton sock. One of the positive things about wool is that it retains its heat-retention properties when wet. That is one reason that it is widely used for outdoor sporting socks. We will take time tomorrow to go over the MCAS practice questions that you worked on while waiting for the data collection to be completed for your lab.

Homework

Honors Physics A Block: Complete the 9.2 Section Review and Practice 9C
Physical Science B Block: Complete the Practice problems and Section Review on page 434
Physical Science E Block: Finish up the open response questions for the MCAS practice packet
Physics F and G: Study for exam

Stupid Snow

What a nasty little surprise to greet us as school was starting - wet, tacky snow. And lots of it. I'll be shoveling until bedtime...

Honors Physics plowed through their Chapter 8 exam and is now set to tackle fluids. We’ve been concentrating on how forces interact with solids and now is the time to examine gases and liquids. Your reading tonight will center around the buoyant force – the upward force generated by a fluid with an object is placed in that fluid.

Physical Science B and E suffered the Chapter 12 exam with great dignity and got started on their reading for the next unit. We now move into a specific form of energy – heat – and its effects on matter. The lab that E block will conduct tomorrow focuses on the conductor/insulator part of the reading. We will test materials for their ability to conduct heat energy. E block should make sure to finish reading section 13.1 and their lab sheet before coming to class tomorrow. As you’ll see, there is a lot of “down time,” in the lab and we are going to fill that time with MCAS practice.

Physics F worked with levers and pulleys in lab and explored how the machines function to make work easier. The contrast between ideal and actual mechanical advantage was noted as was the varying efficiency of the machines. We’ll discuss the lab tomorrow as part of the general review for Monday’s exam.

Physics G discussed yesterday’s lab investigation and then discussed the concept of efficiency. That dratted friction prevents any machine from being 100% efficient and mean old conservation of energy ensures that no machine is more than 100% efficient. Remember to bring with you all your questions for the review session tomorrow. We didn’t cover all the topics in the chapter, so use your slide packet as a guide for studying.

Homework

Honors Physics: 9.1 Section Review and Practice 9A
Physical Science B and E: Read 13.1 and complete the practice on page 424 and the section review on page 426
Physics F: Complete lab write up
Physics G: Complete simple machines worksheet

Exam Prep Tuesday

Honors Physics reviewed their lab lever and pulley lab activities and then moved into a general review for tomorrow’s exam. I will collect the homework we went over today in class before the test tomorrow, so don’t forget the papers at home! The formula sheet that you have seen for every test will be the same one that you will use tomorrow, so just be sure you are able to identify all of the relevant variables in the equations. Starting on Thursday, we begin to look at how forces interact with fluids and hit topics such as buoyancy, fluid pressure, flow rate and gas laws.

Physical Science B and E reviewed for their work and energy exams. We will use the MCAS formula sheet tomorrow, along with a few additional equations that we used in lecture and lab this unit. Take time tonight to rework every type of problem that we’ve encountered and make sure that you can adequately respond to each of the objectives that are at the beginning of each section in the book. Starting on Thursday, we will move away somewhat from motion and begin to focus on one of the forms of energy that we mentioned in this chapter – Heat.

Physics F shared their lists of members of the inclined plane family and then began an examination of efficiency. Due to the fact that some work/energy is always converted into nonmechanical or non-useful forms, a machine can never give out all of the energy/work that you put into it. It always has an efficiency less than 100%. This also means that, machines (including you!) must always be fed with fresh energy to continue to function. Make sure that you are clear about the difference between mechanical advantage and efficiency, as you will examine both of those in your lab tomorrow with simple machines.

Physics G conducted a lab investigation that allowed students to see how levers and pulleys manipulate force/distance to make your work easier. The mechanical advantage and efficiency of the machines and their variations (1st and 3rd class levers; simple fixed, movable and multiple pulleys) was calculated, with data falling about where we would expect it. First-class levers can give MA>1, but third-class levers don’t have that ability. Pulley systems and movable pulleys can give MA>1, due to the increased number of supporting ropes (increased input distance), but simple fixed pulleys give MA=1. Their benefit is in the change of direction of force. Tomorrow, we will review the lab and the basics of simple machines before moving into the concept of efficiency.

Homework

Honors Physics A: Study for Chapter 8 exam
Physical Science B and E: Study for Chapter 12 exam
Physics F: Complete simple machines worksheet
Physics G: Complete lab write up

A Day for Machines

Honors Physics conducted a lab investigation that targeted mechanical advantage and efficiency of levers and pulleys. First and third class levers were tested, with both IMA and AMA calculated and compared. As expected, first-class levers can produce mechanical advantages greater than one, but third-class levers always produce mechanical advantages less than one. Also, the actual mechanical advantage (AMA) was significantly less than the ideal mechanical advantage (IMA) due to friction in the system. Simple fixed pulleys, movable pulleys and pulley systems were then constructed and tested. The results bore out that the simple, fixed pulley has a MA roughly equal to 1, a simple movable pulley has a MA close to 2 and pulley systems have mechanical advantages equal to the number of supporting cords. Have these labs written up for tomorrow, so that we can go over them along with the review worksheet in preparation for Wednesday’s exam.

Physical Science B discussed their tossed ball lab and how it demonstrated conservation of total energy and conservation of mechanical energy. The basketball conserved mechanical energy better than did the balloon, but total energy was conserved in both (and in all) cases. Students then reviewed the basics of conservation of energy and efficiency. Tomorrow, time will be spent reviewing for the exam on Wednesday. Look over the material tonight and come ready with questions.

Physical Science E discussed their conservation of mechanical energy problems and then began work on review material for Wednesday’s exam. We’ll go over this work tomorrow prior to engaging in a general review of the chapter. Make sure to look over the chapter and come to class tomorrow with any questions or problems.

Physics F and G reviewed properties and examples of the lever family and then moved into a discussion of the inclined plane family. The simple inclined plane, the wedge and the screw increase input distance to reduce effort force. Tonight, flesh out your list of members of the inclined plane family and be ready to share that list in class tomorrow. We will finish this chapter this week and the exam looks like it is going to fall on Monday. Budget study time accordingly.

Homework

Honors Physics A: Complete lab write up
Physical Science B and E: p. 411 #21-23 and p. 412 #26,26
Physics F and G: Prepare a list of 20 members of the inclined plane family and complete items #1,3,4,5 of the 8.4 Section Review

The Vampire, Johnny Depp

This is the best news I've heard in a long, long, time...

Confirmed: Johnny Depp's Dark Shadows to begin next year

I watched this show religiously as a kid. Imagine it - a vampire soap opera made in the late 60's. I grabbed the DVD's as soon they became available. If you have never experienced Dark Shadows, you do not know what a hoot-and-a-half you are missing. And a remake by Tim Burton - unfathomable degree of Yipee!

Finally Friday!

Honors Physics discussed the simple machines today, along with mechanical advantage and efficiency. At some previous point in time, most folks have been introduced to the simple machines, so today’s work was a good refresher and an opportunity to tie simple machines to the concept of torque. On Monday, students will engage in a lab that allows them to study the classes of levers and simple/multiple pulley systems for ideal/actual mechanical advantage and efficiency. Tuesday, review; Wednesday exam. Thursday – starting fluid dynamics.

Physical Science B conducted their conservation of energy lab investigation and the results were pretty good. The re-distribution of energy between gravitational potential and kinetic was evident and there was fairly good indication of conservation of mechanical energy. Of course, with a real system we don’t expect conservation of mechanical energy – the conversion of energy to nonmechanical forms robs a lot of the useful energy from the system, and your results definitely bore that out. Have these labs written up to go over on Monday, when we will also start reviewing for the exam, which will be on Wednesday.

Physical Science E had additional time to work on their conservation of energy problems and get extra help from me. As there were only six people present due to the band/chorus concert, moving ahead with new material wasn’t the best option. Monday, we will go over the problem worksheet and discuss the idea of efficiency – how well does a machine conserve mechanical or usable energy.

Physics F and G began their study of simple machines by discussing the basic function of machines and concentrating on the lever family. All machines make work easier, but at a cost. A machine will either multiply your effort force (but at the cost of distance) or multiply your effort distance (but at the cost of force). No machine can multiply both components of the work/torque formula simultaneously. Levers are very good at multiplying effort force, generating a mechanical advantage greater than one, but some, like simple fixed pulleys, only change the direction of the force. Others, like third-class levers, actually diminish effort force, but give you greater output distance in return. Monday, we will examine the inclined plane family and see how its members approach making work easier. Your lab for this unit will investigate the three classes of levers and various configurations of pulleys for ideal mechanical advantage, actual mechanical advantage and efficiency.

Homework

Honors Physics A: Chapter 8 Review Worksheet and Chapter Review #20, 53, 67
Physical Science B: Complete lab write up
Physical Science E: Complete conservation of mechanical energy problems
Physics F and G: Make a list of 30 members of the lever family. Remember not to repeat examples of the same lever - bike wheel and car wheel count as the same, not separate levers.

To Every Thing

turn, turn, turn...

Honors Physics got to have a little fun today after going over their angular momentum and conservation of energy problems. For those problems, streamline your technique by remembering that combined objects in rotational motion (like a bike wheel and reflector) will have the same angular speed, regardless of position and that mass is not a necessary piece of information for the conservation of energy problems, if you are solving for height or velocity. Once we tidied up these problems, students had the opportunity to experience conservation of angular momentum firsthand. Using rotating platforms, folks got to spin and change their mass distribution/moment of inertia and feel the resulting change in angular velocity. Lower the moment of inertia by pulling mass closer to the axis of rotation and expect the angular velocity to increase – and, boy, did it ever. Tomorrow, we hit simple machines in preparation for Monday’s lab with pulleys and levers. Test is looking like it will fall on Wednesday, after all. Tomorrow – simple machines. Monday – lab. Tuesday – discuss lab and review. Wednesday – exam. There you have it…

Physical Science B reviewed the conceptual and mathematical aspects of conservation of energy and then turned this discussion into the conservation solely of mechanical energy. Because of friction, mechanical energy is not totally conserved in systems and this is the basis for evaluating the efficiency of a machine. Remember that a machine can’t be 100% efficient – the energy is never completely retained in mechanical form – and it can never, ever, exceed 100% efficiency. That would mean a creation of energy and energy conservation says that is a major-scale no-no. Tomorrow, your lab will allow you to get hands-on experience with energy conservation using as ball thrown into the air as our experimental system.

Physical Science E reviewed the basics of conservation of energy and then embarked on a series of problems that focus on conservation of mechanical energy. Take your time with these problems. Read them thoroughly, sketch them out, identify every piece of information that you are given, consider what quantities you might need to calculate and how the problem will let you do this. These take a bit more consideration than did last night’s homework problem, so budget your time accordingly. We’ll go over these in class tomorrow and then begin to discuss a practical application of conservation of energy – efficiency.

Physics F and G worked on test corrections, alone or with partners. Have them ready for me tomorrow and we will use the period tomorrow to begin moving into the relationship between work and simple machines.

Homework

Honors Physics A: None
Physical Science B: Read lab sheet. Complete Section Review 12.4 and the Graphing Skills on p. 409 by Monday
Physical Science E: Complete conservation of energy problems
Physics F and G: Complete test corrections

Rolling Along

Honors Physics reviewed one last problem for rotational equilibrium before moving into examining how torque can upset or produce equilibrium through generating angular acceleration. When working with Newton’s 2nd Law for rotational systems, make sure to choose the right shape when picking your moment of inertia formula. The same holds for your calculations with angular momentum and kinetic energy. For angular momentum, we should have a bit of time tomorrow to allow you to experience conservation of angular momentum (provided we complete going over homework problems in time). Exam will fall preferably Tuesday of next week, or possibly Wednesday. Let’s see how the next few days go with machines…

Physical Science B worked on practice problems dealing with conservation of mechanical energy. Yes, I know they were tough…they are supposed to be tough. The only way to learn to work problems is to work many of them and don’t always stick to the easy type. These have you work your brain a bit to figure out how to pull all of the elements of the problem together, but they still really on only two formulas – GPE and KE. Remember, too, that you are only responsible for problems 1-5. We’ll go over them tomorrow and make sure that we are clear on energy and its conservation before moving on to efficiency in machines.

Physical Science E reviewed their conservation of energy lab and then dived deeper into the law of conservation of energy both in concept and in calculation. Tomorrow, you will get some practice problems for conservation of energy that you will work on in class. The problem on which you are working tonight will be useful practice for the set that you’ll tackle tomorrow.

Physics F and G began their study of torque. Torque, the ability of a force to produce rotation, is responsible for the angular accelerations that we calculated in the last chapter. We discussed the effect of force and lever arm on the magnitude of torque and will talk later about how machines use torque to do work. Remember to pay attention to the sign of torque – counterclockwise is positive and clockwise is negative – when working problems. Take some time tonight to look around your house for examples of torque in action. Think about lever arm and how that might explain how some devices work/are constructed.

Homework

Honors Physics A: Practice 8D and 8E
Physical Science B: Complete conservation of energy practice problems
Physical Science E: Solve the following problem:

A boy drops a 1.7 g penny from a window that is 12 meters above the sidewalk. At what speed does the penny hit the sidewalk?

Physics F and G: Complete the torque worksheet

Here Comes The Sun

After yesterday's gloom, the sunshine today is just dandy...let's hope it lasts!

Honors Physics discussed the first and second condition of equilibrium and then turned towards reviewing the homework problems. Most folks have difficulty with equilibrium problems, so don’t feel bad if you pulled your hair a bit while doing homework. What I tend to do is always draw out the situation, with all weights, forces, distances and angles labeled. Then, write the expression for the first condition of equilibrium (sum of all forces equals zero). This may take two expressions if some forces have both an x- and y-component. Then, write the expression for the second condition of equilibrium (sum of all torques equals zero). When working with torques, remember that you can choose any axis of rotation that you wish – if the object is in rotational equilibrium, then it is in equilibrium around any axis that you might choose. Pick an axis through which one of your unknown forces directly passes – this means the force does not contribute to torque around that axis. This eliminates one unknown variable from your net torque calculation. Solve for the other unknown and then return to the expression for the first condition of equilibrium to get the other force. Takes a bit of practice (and patience), but that’s why I gave you another problem like this as part of the homework. Look over what you did today and use the techniques to help you plan your attack on tonight’s problem. Tomorrow, we’ll review rotational equilibrium and then dive into Newton’s 2nd Law for Rotation.

Physical Science B began their exploration of conservation of energy. Whether in a living or physical system, energy is neither created nor destroyed, it is only converted into different forms/types. The total number of joules of energy you begin with, you will end with; however, the energy may or may not be useful for the work you need to do. When we look at usable energy for work in physics, we concentrate on mechanical energy, for our purposes the sum of the kinetic and gravitational potential energy an object possesses. Often, there is not complete conservation of energy when one is transformed into the other, because friction causes some of the energy to be transformed into heat. This will lead us to a discussion about efficiency later in the section. We then worked a few practice problems on the board for conservation of energy and will have more practice with these tomorrow in class.

Physical Science E conducted a lab investigation on conservation of energy, using a ball thrown into the air as the studied system. It took groups a bit to get a good graph of the throw, but when analyzed, these graphs nicely showed the continuous back and forth conversion of kinetic and potential energies. The total conservation of energy was pretty good – we can’t expect it to be perfect due to energy loss from friction and air resistance. We’ll go into conservation energy in more detail tomorrow and begin to work on some mathematical ways that conservation of energy can be used to analyze motion.

Physics F and G underwent the painful examination procedure for Chapter 7. Tomorrow, we pick up with torque, extending our study of rotational motion. We are going to pick and choose from this chapter, however, and will leave some topics in the dust. Torque, center of mass, machines, mechanical advantage and efficiency will be the highlights. We’ll demo conservation of angular momentum, but don’t worry about the mathematical analysis.

Homework

Honors Physics A: Read 8.3 and complete Practice 8C and #21 of the Chapter Review
Physical Science B: Review today’s problems in preparation for tomorrow’s practice
Physical Science E: Complete lab write up
Physics F and G: Read Section 8.1 and complete Practice 8A #1 and 2 and, also, #1,2,3,6, 7 and 8 of the Chapter Review

Return from Turkey Day

Honors Physics A started their discussion of rotational dynamics with a look at torque and moment of inertia. Torque – the ability of a force to produce rotation around a specific axis. We have insert that “specific axis” in that phrase since different axes of rotation are easier to spin around than others. That’s where moment of inertia comes into play. Moment of inertia looks at different configurations of mass and describes the resistance of that shape to rotation. Take a single object and try to rotate it in different ways. Some ways are easier than others – that is due to the distribution of mass around the rotational axis. The more of the object’s mass that is close to the rotational axis, the lower the moment of inertia and the easier is the rotation. Tomorrow, we’ll extend these ideas to conquer rotational equilibrium – how do you calculate the forces and torques on objects that exist in equilibrium? For tonight's homework, if I don't have time to update the class website, you can USE THIS LINK for the solutions for Chapter 8 problems.

Physical Science B went over their gravitational potential energy and kinetic energy worksheet. We then discussed the other forms of energy such as chemical, nuclear, heat and electromagnetic. We will spend time with heat and electromagnetic energy later in the year and may get a chance to hit nuclear, time permitting. You will discuss chemical energy in detail in biology and chemistry. Tomorrow, we begin an examination of conservation of energy, concentrating just on kinetic and gravitational potential as our examples. Exam looks like it will fall on Monday, so you should have plenty of time to prepare.

Physical Science E also discussed forms of energy and took time to analyze the nutritional label of a pack of cheese to determine how energy is apportioned between the main biological molecules – fats, carbohydrates and proteins. Most people don’t realize that the calorie is a unit of stored energy – how much work could you do if you ate this food – and that different molecules store different amounts of energy in their chemical bonds. Tomorrow’s lab will center around the conservation of energy, specifically mechanical energy, but know that all energy is conserved regardless of form or type. Some of it does not remain in a form or type usable for work, though, and that’s what we mean when we say that energy is “lost” in a system.

Physics F watched a video on anti-gravity machines and worked with examples of rotational motion. The rheoscopic balls were especially nice for looking at how individual regions of a rigidly rotating object compare for angular and tangential speed. By tomorrow, you should have your film and activity questions completed, as well as the review worksheet. Exam on rotational motion and gravity tomorrow and then onto torque and machines! Physics G reviewed for the exam and worked on their preparation worksheet. Have your worksheet ready for tomorrow, as they will be collected before the exam. For both sections – the formula sheet will have all of the angular motion formulas available, but make sure that you know what all the variables stand for!

Homework

Honors Physics A: Read section 8.2 in the book and complete Practice 8B
Physical Science B: Complete the 12.3 Section Review
Physical Science E: Read lab sheet for tomorrow’s activity. Complete Graphing Activity p. 409 and 12.3 Section Review for Wednesday
Physics F: Complete lab questions and review worksheet. Study for exam.
Physics G: Complete review worksheet. Study for exam.

This is Actually Educational

Half-Day!

A shortened day today due to the impending holiday and the pep rally. Honors Physics went over their torque lab and shared data with the students who missed the lab due to yesterday's band practice. There were also given an optional bonus question to work on over break. Physical Science E (no B today)reviewed their potential and kinetic energy homework problems and will discuss non-mechanical energy when we return. Physics F and G started pulling together loose ends for Tuesday's exam. On Monday, F Block will watch a video about gravity and engage in more exam review; G block will review for the test.

Homework

Honors Physics A: Complete lab write up, if necessary. Work on bonus problem, if desired.
Physical Science B: Complete potential and kinetic energy problem sheet
Physical Science E: Chapter Review item #24
Physics F and G: Review for Tuesday's exam

Have a safe and fun Thanksgiving!

Honors Physics conducted an investigation of torque and rotational equilibrium. It was a wild and wooly experience, such that I made sure that the laptops were safely removed from the lab benches prior to the lab period. When we think about balance, we are thinking about torque and rotational equilibrium. Those amazing mobiles that people construct are based on these principles. Keep the net torque on the system at zero and there will be no rotation. Masses are carefully placed to generate equal positive and negative torque. We also have to consider linear equilibrium, though. The pieces can’t snap the strings! The second part of the lab had you pull both equilibria together in what looked like a physics version of Twister. However, with effort, rotational and translational equilibrium was attained and the meter sticks finally behaved themselves. We’ll discuss the lab tomorrow and look more deeply into the idea of torque. Here’s a couple of preview videos if you just can’t wait:





Physical Science B went over their lab investigations and discussed their lab data in light of our work with machines. Maximize the separation between the input and output distances and you maximize the mechanical advantage of the machine. Also, don’t expect efficiency to be great – that is one of the tragic costs of using machines. It costs you more work to do the job with a machine than if you had simply done it yourself. Then, we turned our attention to energy and examined gravitational potential and kinetic energies. Is energy stored or is it actively fueling work? Regardless, it is still energy, measured in Joules. The practice worksheet will allow you to work with the GPE and KE formulas and we will go over them on Monday. The answer key is online and can be accessed THROUGH THIS LINK.

Physical Science E went over their kinetic energy homework and, after a review of GPE and KE, worked on a problem set for both energy types. The answer key is online (see the link above) and we’ll go over the work tomorrow in class. Also, as promised, here are a couple of energy videos:





Physics F and G discussed gravity and factors that affect the magnitude of the force of gravity between objects. Mass and distance are the players , with distance having more of an impact than mass. That pesky r²…double the mass, you only double for the force. Double the distance and the gravitational attraction drops to 1/4 the original value. Remember when working problems that when you solve for distance, makes sure that you are solving for distance and not distance-squared. Too often, folks forget to take that final square-root and end up with the wrong answer. Remember that we are looking at next Tuesday as your assessment day. That gives us a couple of review days between now and then, so prepare any questions you have to address in class.
Homework:

Honors Physics A: Complete lab write up
Physical Science B and E: Complete energy problems worksheet.
Physics F and G: Practice 7I #1,2 and Chapter Review items #31, 35, 39, 50

Simple Machine Videos

Here are some videos for Physical Science dealing with work and simple machines. I'll put a couple about energy up tomorrow:









Mechanical Advantage and Friction:

Countdown to Thanksgiving

Honors Physics sat through a quiz on rotational motion and gravity and then got a brief introduction to the concept of torque. The next chapter deals with rotational dynamics and we will move through the same topics that we covered when we looked at dynamics for linear motion. Tomorrow’s lab will focus on the nature of torque and its relationship to balance. Then, the lab will introduce a new perspective on equilibrium. We have been viewing equilibrium as a situation when an object experiences zero net force. However, a ball could experience zero net force (not moving across the ground), but still be rotating. There is another condition of equilibrium, where an object experiences zero net torque that also has to taken into account for rotating objects. Both conditions of equilibrium will be examined in the second part of tomorrow’s lab.

Physical Science B conducted a lab that investigated simple inclined planes and simple levers. Students calculated mechanical advantage and efficiency and tested how changing angle of incline and lever type affected these descriptors. Groups found that increasing the angle for a ramp decreases mechanical advantage – you are having to work against a larger component of the object’s weight as you raise the ramp. For levers, it was pretty quickly seen that even for the same class of lever, changing the positions of the resistance and effort forces had a big impact on mechanical advantage. Think about first class levers like crowbars and shovels in terms of what you learned in lab – why are these tools built the way they are? We’ll go over this lab tomorrow and begin our discussion of energy.

Physical Science E began their investigation of unit by reviewing the basic definition and unit for energy and differentiating kinetic and potential energy. We spent the bulk of the time discussing gravitational potential energy and practicing using the GPE formula. Remember that height is relative for this calculation and you must state or recognize the zero level for height measurement. Also, be mindful of sign…We breezed over elastic potential energy, although it is another stored energy of position. For EPE, the amount of stored energy is dependent of the amount of stretch or compression and how stiff/loose is the elastic material. We’ll go more into this type of energy in Grade 11-12 physics classes.

Physics F and G discussed the fabulous Randolph and used the discussion to review over basic descriptors and calculations relating to circular motion. We then focused in on the different types of forces that can be responsible for circular motion, which will lead us into tomorrow’s discussion of gravity. I’m looking at the assessment for this chapter when we return from Thanksgiving break – probably Tuesday – so keep that in mind for planning your time.

Homework

Honors Physics A: 8.1 Section Review and Practice 8A
Physical Science B: Complete lab write up
Physical Science E: Read p. 394-395 and complete the Practice on p. 395
Physics F and G: Conceptual Challenge p. 262, Practice 7H #1 and 4, Chapter Review items #32, 34.

A Deep Philosophical Question

Flyin' Pigs!

Randolph the Flying Pig was in the house today to drive junior and senior physics disciples crazy. Honors Physics, Physics F and G were tasked to calculate the centripetal force and tension in the string for Randolph while he flew around in a majestic circle. Without any help from me, since I was napping, they had to decide what variables to measure and how to perform the relevant calculations. It was a free-for-all: no lab groups, just anyone working with anyone to get the job done. On Monday, we will go over the activity and talk about the strategies people employed to get their answers. Honors Physics – don’t forget about your Chapter 7 quiz on Monday, also.

Physical Science B and E completed their discussion of simple and compound machines. We concentrated on the inclined plane family today and discussed the function of and examples of simple inclined planes, wedges and screws. Again, I would say take the time this weekend to try and label household items as to the type(s) of simple machines they represent. You might be surprised at what you find! On Monday, Physical Science B will conduct a lab investigation on inclined planes and levers. Physical Science E will start their discussion of energy.

P.S. Maggie N. - You looked FABULOUS today ;-)

Homework

Honors Physics A: Study for Chapter 7 quiz. Work on Randolph issue.
Physical Science B: Read lab sheet. Complete 12.2 Section Review by Tuesday
Physical Science E: Read pgs. 391-393 and complete the Practice on p. 393
Physics F and Physics G: Reflect on Randolph and be ready to continue our discussion of circular motion on Monday.

A day back after a half day is always tough, but everyone muddled through.

Honors Physics A grabbed gravity today and discussed the factors that affect the magnitude of gravitational attraction between two bodies. All matter generates gravity, but the magnitude of the attraction between objects depends directly on the masses of the objects and inversely on the distance between them. Distance is the bigger player, as the relationship is an inverse-square one. A change in mass has less of an effect on gravitational attraction than an equal change in distance. We’ll go over the gravity homework tomorrow and use the remaining class time to review for Monday’s quiz on rotational motion.

Physical Science B reviewed the function of machines and how machines achieve mechanical advantage by manipulating either input force or distance. They then jumped into the specific types of machines, concentrating first on the lever family. We went over the three classes of basic levers, types of pulleys and wheel and axle systems. You might take time today to look around you and see if you can identify the different classes of levers in everyday objects. Tomorrow, we will go over the inclined plane family and the lab that you do on Monday will look at both machine families by letting you investigate simple inclined planes and the three classes of levers.

Physical Science E began their discussion of machines with an overview of the basic function of machines and how machines provide mechanical advantage. They then began to discuss the lever family of simple machines, exploring simple levers and pulleys. Tomorrow, we will finish up the lever family with a discussion about the wheel and axle and then tackle the inclined plane family.

Physics F and G worked on test corrections and/or lab write ups. Tomorrow, we dive deeper into centripetal force and how it affects the motion of matter.

Homework

Honors Physics A: Practice 7I and Chapter Review items #31, 35, 40
Physical Science B: Chapter 12 Review items #28, 29, 31, 32
Physical Science E: Complete the 12.2 Section Review
Physics F and G: Complete test corrections/labs

Cool Points if You Recognize the Reference

PTC Round 1

Very little to report today, as only two classes met due to early release for parent-teacher conferences. Honors Physics discussed the nature and action of centripetal force and took class time to work through some thought questions centering on centripetal force and circular motion. Tomorrow, gravity! Physical Science B examined the basic definition of machines and what machines can do with force and distance to make work easier. Remember, nothing comes for free – for every multiplication given to you by a machine, it lessens something else. Multiply force, lose distance; multiply distance lose force. Because of this inverse relationship, the formulas for calculating mechanical advantage (MA) are flip-flopped. MA = F_o/F_i or d_i/d_o. Starting tomorrow, we begin to examine the specific simple machines and how they manipulate force and distance to perform work. For both Physical Science B and E – test corrections due tomorrow.

Homework

Honors Physics A: Chapter Review items #27, 28, 34, 36, 38, 53
Physical Science B: Complete test corrections

Honors Physics went over their Chapter 6 exams and then moved into the tangential speed and acceleration associated with rotational motion. The variation in tangential speeds between inner and outer regions of a rigidly-rotating body are what make the consistent angular speeds possible. We then added a third acceleration to the mix – centripetal acceleration. Directed towards the center of the rotation, centripetal acceleration takes the job of changing the direction of motion and keeping objects moving in a circle. The speed of the motion is handled by the tangential acceleration. So, two different accelerations work to produce the velocity changes – tangential for speed, centripetal for direction. Tomorrow, we discuss the forces that produce centripetal acceleration – centripetal force – and demonstrate how different forces can take on that role for circular motion.

Physical Science B and E went over their fluid forces exam. For this exam only, since it was pretty math-heavy and much of the material was not in the textbook (although it was in the class notes), I am allowing test corrections. As stated in class – for conceptual questions, tell me why you chose the wrong answer and explain why the correct answer is actually correct; for problems - show the work to solve the problem correctly and discuss why you got the problem wrong in the first place. For each item you correct correctly, I’ll give you back one-half of the points you missed. For both classes, get all the help you need from me, parents and friends, but have the corrections to me on Thursday.

Physics F conducted their centripetal force lab. You will have time in class tomorrow to complete the lab and its write up, but you might spend a little time tonight organizing your data to make tomorrow run more efficiently.

Physics G completed their work on the centripetal force lab. For two different constant radii, an increase in the centripetal force required a higher tangential velocity for the motion to proceed. Comparing trials with the same mass, the larger radius required a higher tangential velocity to keep the motion going. We will review tangential and angular speeds and accelerations tomorrow and toss centripetal acceleration and centripetal force in to the mix.

Homework

Honors Physics A: Complete Practice 7G and 7H
Physical Science B and E: Work on test corrections
Physics F: None
Physics G: Complete the 7.2 Section Review and p. 270 # 17,18,20

No, I Don't Know When Report Cards Come Out

I'm not sure if people are enthusiastic or apprehensive about getting their quarterly marks, but believe me when I say that once my grades are turned in, report card duties are out of my hands...

Honors Physics reviewed their centripetal force lab and results varied, as expected. Most groups found good relationships between the measured centripetal force and the calculated centripetal force, but there were significant sources of error possible, depending on your setup. We then turned attention towards defining and calculating basic descriptors of circular motion – displacement, speed and acceleration – and discussed how these values were analogous to their linear counterparts. This is important to keep in mind as we move through this unit – if you get stuck trying to figure out how to calculate something, think about how you would calculate the linear variety of the property and rewrite with angular equivalents. Tomorrow, tackling tangential speed and two more accelerations!

Physical Science B and E were introduced to the concepts of work and power today and the formulas for solving problems in these areas. Remember that for work to be done by a force there has to be displacement and the force itself had to cause or act in a direction opposite the displacement. We contrasted lifting an object (work is done by your arms) with carrying an object (work is not done by your arms) and examined examples of positive and negative work. For power, make sure that you are very clear that power is the rate at which work is done/energy is transformed. Machines with different power ratings can do the same amount of work – the higher power machine just does it in less time. For problem solving, it is quite common to first have to calculate the work done on or by an object and then use that value for your power calculation. It could go even further than that – you might have to calculate distance and/or force first and then calculate work before solving for power. Just remember to work backwards – what do you need to solve for, what do you need to solve for that variable, what do you need to solve for the variables necessary for the final solution, etc. Plan your attack and if it doesn’t work, try something else until you find the correct method.

Physics F reviewed basic descriptors of rotational motion and then moved into tangential speed and acceleration. Whereas angular speed and acceleration are the same for all points on a rigidly rotating body, tangential speed and acceleration change with different points. In fact, they have to change in order to keep the angular quantities the same! We then looked at the idea of centripetal acceleration – the acceleration involved in the change of direction characteristic of circular motion. Tomorrow’s lab will allow you to measure centripetal acceleration and the force that produced it (centripetal force) and test which variables affect their magnitude.

Physics G conducted their centripetal force lab and no one received a concussion – score! By measuring period and radius of a rotating object, calculations of centripetal acceleration can be conducted. Combined with the mass of the washers, centripetal force could be established. Radius and mass were varied and their effects on centripetal force was noted and graphed. We will discuss centripetal acceleration tomorrow and also the linear quantities of tangential velocity and acceleration. Have your labs completed so that we can discuss them as part of class.

Homework

Honors Physics A: Practice 7D, practice 7E #4, Practice 7F #2,3
Physical Science B and E: Complete Practice and Section Review questions/problems on page 284
Physics F: Complete the 7.2 Section Review and p. 270 # 17,18,20
Physics G: None. We will work on the lab in class tomorrow

Friday the 13th!

Gloomy, clammy but no murderers wearing hockey masks. I'll give the day an "E" for effort...

Honors Physics conducted a lab investigation that was a little off our regular protocol. Rather than a detailed lab sheet, the basic technique was described, but the actual details of the apparatus and experimental protocol was left up to the students (especially for testing other variables). Groups had to use a motion detector and force sensor to assess the centripetal force on a pendulum system and relate it to the tangential velocity, pendulum mass and radius. Does F_c = mv_t²/r? After the basic experiment, students had to change the mass, radius and displacement variables and see if they affected the relationship and/or the magnitude of the centripetal force. On Monday, we will discuss the lab and jump headlong into angular motion.

Physical Science B and F endured their forces in fluids test. Scores were on the low side, for both the conceptual questions and the math problems. We will go over the exams next week and work to firm up the information in people’s minds. Also on Monday, we begin our study of work, power and simple machines. Make sure to have the homework problems completed and Physical Science B should have their lab write up prepared.

Physics F and G worked on understanding the nature of the radian and how we use radians to discuss displacement in circular motion. Students conducted a brief activity to see how the value of a radian is determined, using wire and circles drawn with a compass. Sure enough, it takes about six and a quarter lengths of wire, each the length of the radius off a circle, to cover the circle’s circumference. The angle swept out by one of those pieces of wire equals one radian. A full circle equals 2π radians. Work to drill the concept of radians and how to work with them in problems (and on your calculator) into your brain. For the next two chapters, displacement of objects engaged in circular motion will need to be in radians to analyze the motion mathematically.

Homework

Honors Physics A: Complete lab write up
Physical Science B: Complete lab write up. Complete practice problems on page 379 and 381
Physical Science E: Complete practice problems on page 379 and 381
Physics F and G: Physics G should read their lab sheet, Physics F has no homework

A Case of the Mondays

Pretty much everyone today said it felt like a Monday. Know what? They're right...

Honors Physics , Physics F and G engaged in their Chapter 6 graded learning experience today and will move on to circular motion tomorrow. We have been neglecting the fact that many objects revolve or rotate, even when experiencing linear motion. The next two chapters will allow students the opportunity to examine rotational motion and incorporate that material into their overall examination of mechanics. In Chapter 7, descriptors of circular motion will be introduced, as will the nature of the forces involved in maintaining circular motion. The lab for this unit will focus on centripetal force, how it can be measured and what factors affect the magnitude of the centripetal force an object in circular motion experiences. Honors Physics works on that tomorrow, and Physics F and G will conduct the investigation on Monday and Tuesday. One point to note about this unit: make sure that your calculator is set to receive measurements in radians, not degrees. Ask me for help if you have need. When we work with displacement for rotational motion, the proper value is in radians – another way, besides degrees, to report fractions of a circle. If you have yet to work with radians and the unit circle in math, we’ll do a bit of review at the beginning of the unit which should bring you up to speed.

Physical Science B worked on their buoyant forces lab and got quality results for congruence between apparent loss of weight by an object and weight of water displaced by the object. Their calculated values were pretty close to the measured values, not exact, but there is always a margin for error in experiments. Then, they had a bit of time at the end of the period to review material for tomorrow’s exam, which was what Physical Science E worked on all period. Some of the math required for this section is not on the MCAS formula sheet, so I’ll have those additional formulas available for you tomorrow. For both sections, study the textbook, notes and worksheets and please don’t forget your calculators. Here is a worksheet with more practice problems for hydraulics, pressure at depth and buoyant forces.
P.S. Mikaela D - found your Buoyant Forces lab sheet (was caught in the staple of another student's work).

Homework

Honors Physics A: Read lab sheet. Complete 7A #1-3, 7B #1-3 and 7C #1,2 by Monday
Physical Science B: Complete lab write up by Monday. Study for tomorrow’s exam
Physical Science E: Study for tomorrow’s exam
Physics F and G: Read 7.1 in the book and complete p. 252 #1 and p. 269 #1-5

Exam Prep Tuesday

Honors Physics, Physics F and G worked on review for their Chapter 6 exam, which is scheduled for Thursday. Be able to work with momentum and momentum change of single objects, the impulse-momentum theorem and conservation of momentum and kinetic energy for a system. On Friday, we change gears somewhat and begin our unit on circular motion. Honors Physics will engage in a lab investigation that allows students to explore factors affecting the centripetal force acting on an object in circular motion and how aspects of translational motion can be used to calculate centripetal force and acceleration.

Physical Science B reviewed their self-created fluids problems. Thanks to Haley, Courtney and Cara for volunteering to put their problems on the board and walk through the solutions with the class. Tonight, add on a problem for hydraulics devices, to make sure that you can evaluate those systems, as well. On Thursday, students will conduct a lab investigation centering on Archimedes Principle and buoyant forces. There will also be time allotted to address any questions prior to Friday’s exam.

Physical Science E discussed Bernoulli’s Principle and everyday examples of Bernoulli’s Principle in action. We analyzed flight, smoke rising in a chimney, perfume atomizer function and kite flying in terms of Bernoulli’s Principle and did a couple of demonstrations, to boot. On Thursday, review time for Friday’s exam. Come prepared with questions so that we can address them as a class.

Homework

Honors Physics A: Review for exam
Physical Science B: Create a unique hydraulics device problem
Physical Science E: None
Physics F and G: Review for exam

Oh No! Snow!

Every year I hope and hope that we'll have a snowless winter - something that would suit my Southern blood perfectly. And every year, my hopes are dashed. Stupid Mother Nature...

Honors Physics reviewed the elastic, inelastic and perfectly inelastic collisions and then jumped into a mish-mash of problems that require the use of skills dating back to the beginning of the course. Such is the way of physics…keep in mind your studies of kinematics, conservation of energy, projectile motion and make use of any tools in your academic tool bag to jump on these problems. We’ll go over them on Monday, but the link to the solutions are still on the blog post a few days ago. General review after we discuss these problems and then exam on Tuesday.

Physical Science B completed their overview o f buoyancy with a discussion of the homework questions. It was good to hear people thinking in terms of forces and pulling together succinct answers for the questions. We then turned our attention to Bernoulli’s Principle – the pressure in a fluid is inversely proportional to the velocity of the fluid. We linked this to conservation of energy, which we will take up in more detail in the next chapter. Bernoulli’s Principle combined with the nature of fluids to move from areas of high pressure to areas of low pressure has some interesting effects that we observe in daily life, like smoke rising up a chimney, assisting in flight, allowing perfume atomizers to work, etc. A few examples of Bernoulli’s principle were demonstrated in class. Note to parents: I am not responsible if your child goes home and sprays water all over your house to show you what he/she learned in school today.

Physical Science E conducted a lab investigation on buoyant forces. Students directly measured the apparent loss of weight by an object submerged in a fluid, the weight of the displaced fluid and calculated the theoretical buoyant force using the volume of an object and the density of fresh water. Groups obtained good results: the apparent weight loss was close to the weight of the displaced fluid which was pretty close to the calculated buoyant force. It was clear, based on the direction of the net force acting on the object, why the 500-gram mass and rock sank, but the wood floated. On Monday, we will discuss Bernoulli’s Principle. For both B and E Blocks, start looking for a test at the end of next week. The likely day is Thursday, but if people need more math practice, we might have to move it to Friday.

Physics F and G discussed the types of collisions in which objects can engage and how well kinetic energy is conserved in each type. Elastic collisions are good at conserving kinetic energy, but most collisions show definite kinetic energy losses due to deformation of objects, sound production, and internal energy increases. Assume in problem solving that if a collision is not elastic (pure conservation of kinetic energy, objects separate after collision) that a collision is perfectly inelastic (objects stick together as a single object and demonstrate kinetic energy loss). On Monday we will begin reviewing for the momentum exam, which looks like it is going to fall on Thursday, so take time to review the chapter this weekend and pull together a list of questions that you would like to go over next week.

Homework

Honors Physics A: Chapter Review items #27-30, 32, 45, 46, 52, 54, 57
Physical Science B: None
Physical Science E: Complete lab write up
Physics F: p. 230 #2,4 and Chapter Review #27-31
Physics G: None

Conserving Momentum

Honors Physics reviewed conservation of momentum and then turned to the classes of collisions. Even though all collisions are marked by conservation of momentum, not all collisions (actually a puny proportion) will be marked by conservation of kinetic energy. Elastic collisions – no deformation of objects, no sticking together, no loss of energy to sound or internal energy – they just don’t happen on a regular basis. Some collisions get pretty close, like a hard rubber ball bouncing on a smooth marble floor, but most collisions won’t proceed with no deformation or loss of energy to a nonmechanical form. The other side of the spectrum is also rare: the perfectly inelastic collision. Objects sticking together completely and moving as one discrete unit does not describe most collisions. Normally, we see things in between these extremes and these collisions, the inelastic variety, form the bulk of common experience. For our purposes, collisions will either be elastic or perfectly inelastic and this is the types of collisions you’ll find in the homework problems tonight. Tomorrow, we’ll go over those problems and work on some mixed review material to start preparing for Tuesday’s exam.

Physical Science B and E went over their Archimedes’ Principle problems and completed their discussion of density and buoyancy. Students had time to work on some conceptual questions concerning buoyancy and Physical Science E will conduct a lab investigation tomorrow that will allow them to examine buoyancy in more detail. They will get the opportunity to measure apparent losses of weight, weight of displaced fluid and calculate the theoretical buoyant force acting on an object. Physical Science B will begin a discussion of Bernoulli’s Principle tomorrow – the motion of fluids from high to low pressure and how that motion can affect the motion of objects in the path of the fluid.

Physics F conducted the impulse-momentum lab and got results comparable to Physics G. The impulse on an object approximated, in most cases, the change of momentum of the cart and looser elastic materials showed a marked longer time interval for the momentum change to occur than did stiffer elastic materials. The force-time graph showed a shallow “hill” for the impulse acting on the object for loose elastics and a sharp peak for more elastic materials. Consider that when thinking about forces that you experience in daily life and how you could increase or reduce the size of those forces by using time.

Physics G discussed conservation of momentum – the total momentum of a system stays the same, although the momentum of individual objects in the system can change. We explored different types of interactions within systems and how momentum was conserved in each case. Tomorrow, we will discuss the different classes of collisions and emphasize that momentum is conserved for each class. Kinetic energy, though…that’s another story.

Homework

Honors Physics A: 6E and 6G. For 6G, only complete the Part B portion for number 1. You can skip it for the rest of the questions.

Physical Science B: Complete buoyancy questions
Physical Science E: Read lab protocol sheet and complete buoyancy questions
Physics F: Complete lab write up
Physics G: Read 6.3 and complete the 6.3 Section Review #2, 4 and Chapter Review #27-30

The Frost is on the Pumpkin

As the temperatures fall, start carrying around an extra jacket in your backpack. You are going to find that some classrooms will be like Antarctica and others will more resemble Death Valley. Make sure that you can vary your layers accordingly...

Honors Physics reviewed their impulse-momentum labs today and related the results to what we already know about applied and restoring forces of elastic materials. We then turned our attention to conservation of momentum and how Newton's Third of Motion and the impulse-momentum theorem lead to the conservation of momentum in systems. I haven't had a chance to update the course website lately, so I'll put a link to the momentum chapter solutions here so that you can check your work from home. Tomorrow, we'll go over the homework problems and then toss a look back to energy and track the conservation (or lack thereof) of kinetic energy in collisions.

Physical Science B and E reviewed Archimedes Principle and then spent time practicing the mathematical applications of buoyancy. Your homework problems should, like all word problems, thought of as puzzles or mysteries. How do you take what you are given and expected to know and use it to find the answer? Try one technique and if that leads nowhere, try something else. Things to remember when working buoyancy problems:

• The volume of the object is equal to the volume of the displaced fluid.


• The mass of the object and the displaced fluid must be in kilograms in order to calculate weight in Newtons


• The density formula can be used to calculate mass, volume or density of either the object or the displaced fluid. Consider how to use this formula with the information given in the problem to help you along towards the solution.

The answers for your homework problems:

1. F_g = 2.7 x 10⁵ N; F_b = 4.4 x 10⁸ N; object floats


2. F_g = 1.82 N; F_b = 0.15 N; object sinks


3. F_g = 73 N; F_b = 2.2 x 10³ N; object floats; density = 0.17 kg/m³


4. F_g = 11.8 N; F_b = 4.6 N; object sinks; density = 11 g/cm³

Physics F discussed conservation of momentum and how this principle can be used to analyze motion in multi-body systems. Keep in mind that the total momentum of a systems is conserved, but the momentum of individual objects in the system will change after the collision. We related Newton's 3^rd Law of Motion and the impulse-momentum theorem to explain why conservation of momentum holds true and the pattern of momentum change in collisions. Tomorrow's lab will let you analyze momentum and impulse in more detail.

Physics G conducted a lab that concentrated on the impulse-momentum theorem. The agreement between the impulse delivered on an object and the object's momentum change was tested, as was the effect of elasticity on the impulse delivered by a material. We will go over this lab tomorrow and then take on the concept of conservation of momentum.

Homework

Honors Physics A: Practice 6D and 6.2 SR #2,4
Physical Science B and E: Archimedes' Principle problem sheet
Physics F: Read lab protocol sheet
Physics G: Complete lab write up

Honors Physics conducted a lab investigation that focused on the impulse-momentum theorem. The impulse (FΔt) an object experiences is equal to the object’s change in momentum (Δp). A force sensor and motion detector was used, which allowed measurements of force, time and velocity to be taken and used to check how momentum change corresponded to the impulse delivered by an elastic material. Groups got some choice as to the type of elastic material used and it was quickly evident that stiff materials delivered a greater impulse to the carts than did looser materials (given the same push to the cart). We will go over the lab in class tomorrow and begin our discussion of conservation of momentum.

Physical Science B reviewed their pressure/depth lab and then went over the homework problems that had tasked them to use the pressure formula that they later derived from the lab activity. Folks seem to have done a good job with these problems – keep in mind which variables are constants, which information (such as density) that is given in a problem can be carried to other problems, and which direction you choose (up or down) to be positive/negative. Students then began to examine the concept of buoyancy, Archimedes’ Principle and the nature of buoyant force. The role of the buoyant force in promoting floating or sinking was discussed and the link between density and the magnitude of the buoyant force (and weight of the object) was investigated. Physical Science E also went over their pressure/depth problems and moved through the concept of buoyancy.

Physics F and G worked on correcting their work/energy exams. Grades were a bit low on this test across the board, so make sure to take care with your corrections that you understand your mistakes. The midterm and final are both cumulative, so you will definitely see this information again.

Homework

Honors Physics: Complete lab write up
Physical Science B and E: None
Physics F and G: Complete test corrections

Force and Momentum

Honors Physics began their discussion of momentum with an overview of impulse and the impulse-momentum theorem. I emphasized today and will reiterate it again to keep a close eye on the signs for velocity. Momentum is a vector, and takes the direction of the object’s velocity. Momentum change takes into account a change in both the direction and magnitude of the velocity, so watch closely how you set up your equations. Tomorrow’s lab activity will allow you to measure the impulse on an object and compare it to the change of momentum the object experiences. We’ll use a variety of elastic materials for your tests so that you can demonstrate and reflect upon the importance of choosing proper materials in construction, engineering and manufacturing.

Physical Science B conducted a lab activity that allowed them to examine the relationship between depth and fluid pressure. As we discussed in class, with greater depth comes greater pressure in a body of fluid. For the same area (the opening of the tubing, in this case), greater depth means a greater weight of fluid pressing down on the mass. Voila! Greater pressure. The mathematical relationship that you worked out in the expression told you that the pressure change was constant – the relationship was linear – and that the equation of the line you derived matched the equation for pressure/depth that we worked with in class on Friday. Tomorrow, another aspect of forces generated by fluids: buoyancy.

Physical Science E went over their Pascal’s Principle homework problems and we reviewed Pascal’s Principle before moving on to the changes in fluid pressure with depth. Using last week’s lab as an example, we discussed the equation used to calculate fluid pressure at any depth in any fluid and worked on practice problems using this formula. We’ll go over those tomorrow and then move on to the concept of buoyancy.

Physics F and G worked on test corrections. Make sure for your corrections that you show all work and explain for questions why the correct answer is actually the correct choice. Some folks are getting a little lazy about doing their corrections and I am going to stop accepting corrections that are not submitted with the proper information. Same goes for homework – homework should be completed and show all work. A few people are trying to submit homework that does not show work and/or does not show the required corrections. That is going to come around to bite you, so get back on track, pronto!

Homework

Honors Physics: Read lab sheet
Physical Science B: Complete lab write up
Physical Science E: Pressure As a Function of Depth problem worksheet
Physics F and G: p. 233 #17-24

Here's Hoping This Doesn't Happen to You

Costumes! Costumes! Costumes!

I was great to see so many people get in the spirit and dress up for Halloween. Try not to eat too much candy this weekend nor spook too many little kids...(a few is fine, though)

Honors Physics and both Physics sections underwent their painful examination process. Monday we begin the momentum unit!

Physical Science B discussed pressure variations with depth in a fluid. For the same area of object, with increasing depth comes an increased force (weight) due to the greater amount of water on top of the object. The lab that you will conduct on Monday will allow you to investigate this phenomenon more thoroughly, so make sure that you have read over the lab instructions and completed your practice problems in preparation. CLICK HERE for a copy of your pressure and depth worksheet and solutions key.

Physical Science E examined Pascal's Principle and how it can be used to design hydraulic devices. It seemed like people were getting the hang of solving hydraulics problems, so I'm confident you will do a good job with them over the weekend. CLICK HERE for a copy of your pressure worksheet and solutions key. We'll go over them on Monday and begin to discuss the topic of your last lab - pressure variations with depth.

Homework

Honors Physics A: 6B, 6C #1 and #6, 9 and 16 of the Chapter Review
Physical Science B: Read lab sheet and complete pressure and depth worksheet
Physical Science E: Complete Pascal's Principle worksheet
Physics F and G: 6A #1 and 2, 6B #1 and p. 232 #1-3, 6

Bracing for Tests

Honors Physics had the chance to go over their homework for the Power section of the chapter and used the remainder of the class to review for tomorrow’s exam. As usual, we walked through the chapter highlighting concepts and skills and took time to address questions people had about the material or the problem-solving techniques. Monday, we begin our unit on momentum.

Physical Science B went over their Chapter 11 exams and then discussed Pascal’s principle and the function of hydraulic devices. Hydraulic devices multiply our effort force, so that we can successfully work against a resistance larger than what we could work against alone. We’ll go over the homework problems tomorrow and work a few additional ones to make sure that people have a good grasp of the math. Then, we begin to discuss how the force of gravity affects pressure in fluids and that will lead us into Monday’s lab which targets this idea specifically.

Physical Science E reviewed yesterday’s lab and began a discussion of how forces are generated within fluids (which then leads to pressure generation in fluids). We then tuned to the idea that fluids move “down” pressure gradients – they move from areas of higher pressure to areas of lower pressure. This can have an impact on any matter that stands in the path of the moving fluid and we discussed the implications for living and physical systems subject to pressure imbalances. Tomorrow, we’ll take up a discussion of what happens to fluids when they aren’t allowed to move to a lower pressure area when the pressure in one area of the fluid experiences an increase. The transmission of pressure by a fluid, equally and in all directions, has practical applications that we will investigate with a study of hydraulic devices.

Physics F and G reviewed for tomorrow’s exam. We went back through the chapter and worked through any problems or questions that people had about the material. You can rest assured that there won’t be any problems on the test like #34 of the Chapter Review, but you should be able to perform simple calculations for work, kinetic energy (and the work-kinetic energy theorem), both potential energies, energy conservation and power. If you have any additional questions, stop in tomorrow morning before school and we can address them at that time. On Monday, we will extend our discussion of forces and energy to the concept of momentum and its conservation.

Homework

Honors Physics A, Physics F and G: Study for exam
Physical Science B: p. 96 #26-28
Physical Science E: None

Wet Wednesday

Honors Physics completed the work and energy unit with a discussion of energy conservation and power. As you work problems with energy conservation, remember to take into account all forms of mechanical energy present at the beginning and end of the situation in question. Also, if elastic potential energy is in the picture, you can’t cancel out mass in the way you can when only kinetic energy and gravitational potential energy are involved. It also pays to take time to look at a problem wearing your force/kinematics hat, as well as your work/energy hat. Consider how you would describe or explain a situation using forces and kinematics and see how that description/explanation can also be matched by using work and energy concepts. When you get to the power problems, you need to reflect on the variety of ways that we can express work – force x distance, change in energy, etc. – to see how best to approach the power issue. Also, don’t forget the force x velocity derivation. That can come in handy in certain situations. Tomorrow, exam review. Friday, exam.

Physical Science B began their study of forces in fluids today with a discussion of pressure. Make sure that you are clear about the difference between force and pressure and how manipulating force and area create different pressure situations. We then turned towards the tendency of fluids to move from areas of high pressure to areas of low pressure and the implication this motion has for matter that lies in a fluid’s path. We discussed breathing, drinking from a straw, vacuum-cleaner function and hazards of traveling in space without a pressure suit. Tomorrow, we take up the possibility that fluids are blocked from motion – what happens if you apply pressure to one part of a fluid, but don’t allow the fluid to move? Think hydraulics…

Physical Science E had a wet and wild lab experience. The pressure change in a water column due to depth was investigated and, despite a few floods, data for all groups was great. A clear linear relationship between pressure and depth was witnessed: with greater depth comes greater pressure. The same trend exists in all fluids, including the atmosphere. The pressure is highest at sea level and decreases with altitude. The types of problems you worked at the end of the lab are typical of those that scientists and engineers use when they are designing equipment or experiments to work at a certain depth in an ocean or lake or at a height in the atmosphere. Tomorrow, we’ll review the lab and begin discussing the source of pressure in fluids.

Physics F and G discussed power and cleared up some misconceptions about the concept of power. We took time to complete going over all the previous homework problems and that will lead us into our exam review tomorrow. Look over the chapter tonight and come with any and all questions for exam preparation.

Homework

Honors Physics A: Complete Practice 5F #1,2 and p. 195 #33-36
Physical Science B: None
Physical Science E: Complete lab write up
Physics F: Complete 5.4 Section Review
Physics G: Study for exam

Tuesday is SnoozeDay

Leave work, get dogs from daycare, feed said dogs on return home, flop on couch and take nap. That is my plan and I'm sticking to it...

Honors Physics, although sparsely populated due to the Mathematics Field Day trip, discussed elastic potential energy and reviewed the homework problems for the work-kinetic theorem, gravitational potential energy and elastic potential energy. Tomorrow we will draw these together and discuss conservation of mechanical energy, so be ready to think back to your lab activity as it will be used as an example of energy conservation. We should also have time to discuss power, the rate at which work is done or energy is converted. Exam looks like it will fall on Friday, not next week, so time budget accordingly.

Physical Science B and E took their exam on forces and momentum. Tomorrow, we jump back in the book to attack how forces and involved with fluid systems. We’ll look at liquids and gases, discussing such topics as buoyancy, pressure, the gas laws and density. Tomorrow, B Block will begin a discussion of buoyancy and Archimedes Principle. E Block will engage in a lab activity that will allow students to study the pressure changes with depth in a water column. We will make some modifications to the apparatus, owing to the fact that the caps I bought to fit the acrylic piping don’t fit (even though the nice man at the hardware store said they would), so make sure to pay close attention to the pre-lab overview to correct assemble your experiment.

Physics F worked on their conservation of energy in simple harmonic motion lab. Our discussion yesterday gave you some ammunition for the preliminary questions and for the analysis of the graphs of displacement, velocity, kinetic energy, elastic potential energy and total energy over time. Reflect on this material when you pull together your conclusion for the lab synopsis.

Physics G discussed conservation of energy, with special emphasis on conservation of mechanical energy. With the presence of friction, the conversion between kinetic and potential energy is not absolute. Some energy is always tuned to the nonmechanical form of heat. However, in low-friction situations, the loss of mechanical energy is sufficiently low that conservation of mechanical energy can be used to make predictive calculations. Tomorrow, we discuss power and begin reviewing for the exam on Friday.

Homework

Honors Physics: Practice 5E
Physical Science B: Read pgs. 80-86 and answer #19 on page 95
Physical Science E: Read lab sheet and pgs. 80-86. Complete #21 and #34 on page 95.
Physics F: Complete lab write up
Physics G: Read 5.4 and complete the 5.4 Section Review