12/24/09
12/22/09
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
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
12/21/09
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
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
12/19/09
12/18/09
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
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
12/17/09
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 = Po + 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
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
12/16/09
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
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
12/15/09
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
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
12/14/09
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
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
12/9/09
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
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
12/8/09
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
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
12/7/09
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
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!
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!
12/4/09
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.
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.
12/3/09
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
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
12/2/09
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
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
12/1/09
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
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
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