B and C Blocks tackled adding more descriptors to simple harmonic motion today - amplitude, the maximum displacement; period, the time for a single oscillation; frequency, the number of oscillations per second. We looked at which factors affected oscillation period for the mass-spring system (mass and spring constant) and the simple pendulum (length and acceleration due to gravity) and how to use those values to calculate period. In our next installment of class time - wave properties!
F Block continued with their Pendulum Periods lab, using the block to graph their data on the computer and make conclusions as to which factors impact the period of oscillation of a simple pendulum. Once the key factor was discovered (length), students manipulated the period vs. length relationship to find the exact mathematical connection, which was ultimately the formula we'll be looking at in class.
E Block conducted their Pendulum Periods lab and some groups completed their graphing on the computer. If your group did not, simply make the graphs on your graphing calculator, in Excel or use an online graphing simulation. I will be looking for labs for Thursday, so don't stress getting them ready for tomorrow.
1/31/12
1/30/12
On The Road Again
We're back in the swing, and swing is a very appropriate term for our current chapter - vibrations and waves. B, C and E Blocks discussed the characteristics of simple harmonic motion and examined how mass-spring and pendulum systems demonstrate this pretty well. Make sure you can describe what is happening to kinetic energy, potential energy, restoring force, acceleration, velocity and displacement during an oscillation cycle for both of those systems. We took time to show how Hooke's Law satisfies the relationship that restoring force is proportional to displacement for spring systems and for B and C Blocks, harkened back to our lab on conservation of energy for simple harmonic motion to further nail down these ideas. Tomorrow, B and C begin looking a other physical descriptors of simple harmonic motion such as period and frequency and how they can be measured/calculated. E Block will start on their Pendulum Periods lab...
...which is what F Block worked on today. The period of an oscillation is the amount of time required to make one full trip back to the start (crossing equilibrium twice). Period is measured in seconds and we'll look more closely at its relationship to frequency (the number of oscillations per second) in a couple of days. Groups tested three physical features of a pendulum that might influence period: mass, amplitude and length. Tomorrow, we'll graph out our data and draw some conclusions. Then its on to looking at other features of pendulum motion that the other sections hit today.
...which is what F Block worked on today. The period of an oscillation is the amount of time required to make one full trip back to the start (crossing equilibrium twice). Period is measured in seconds and we'll look more closely at its relationship to frequency (the number of oscillations per second) in a couple of days. Groups tested three physical features of a pendulum that might influence period: mass, amplitude and length. Tomorrow, we'll graph out our data and draw some conclusions. Then its on to looking at other features of pendulum motion that the other sections hit today.
1/26/12
1/25/12
The Midterm March
B and F Blocks had their midterm exams today and, although I will see F Block tomorrow, I won't see B Block until Monday when everyone starts their unit on vibrations and waves. We'll hit the basics first then move into a more detailed study of sound and light. Our lab for our next chapter will focus on the factors affecting the period of oscillation of a pendulum and a fun time will be had by all...
1/24/12
One Set Down
C and E Blocks had their midterm exams today and B and F Block will endure them tomorrow. Not much else to say for things going on, but to remind B and F folks that I am here before school tomorrow if they have any last-minute questions. Good Luck!
1/23/12
Midterms
Well,everyone had a day of whatever help they needed for the upcoming midterm exams. C and E are on the chopping block tomorrow and B and F follow on Wednesday. Remember basic test-taking strategies:
Good luck everyone!
- Don't come into the test hungry, thirsty or needing a restroom-break. Take care of all of that ahead of time.
- Make sure to have all materials with you such as your writing utensil and calculator. A calculator is especially important since the riff-raff ones I have in class may not be the most efficient ones with which to work your problems.
- Use basic logic and common sense - if an answer doesn't make sense, it is probably not the right answer. Physics is all about the real world, so use your instincts.
- Eliminate options for multiple-choice questions to increase the probability of being right if you have no choice but to guess on an item.
- Skip questions you don't know and come back to them later. Another question might jog your memory or give you a hint and wasting time on a question that you're weak on lessens time you have to work on questions you feel confident about.
- Read questions carefully - don't read the first few words and assume you know what the rest of the question says.
- You have seen all of the information before - think about what concepts the question might target based on the information given before you start to line up formulas.
- Bring work with you - if you finish early, you need something to keep you busy so that you don't resort to chatting and wind up in hot water.
- Study so you know the information - not so you can figure it out on the test, since that makes you take far longer on the test than you should and for midterm and final exams you should not count on receiving any extra time to finish your test.
Good luck everyone!
1/20/12
Day is Done
Everyone is finished with the material for Chapter 11, with F Block going over the ideal of entropy in class today. E Block worked on their Boyle's Law lab after doing a run through of the chapters for the midterm exam. B and C Blocks did the same and then began to look over their practice tests for the midterm and ask questions that they had prepared for review. Remember to ask me for any help that you need or extra problems to work on and if there is something that comes up over the weekend, email me. If you need a video made of how to solve a specific problem, email me early so I can have time to get it done and get it posted. Monday after school is teacher meetings, so I won't be available to stay after - put an X through that on your calendar as extra-help time. Have a great weekend!
1/19/12
Facing Midterms
Today saw the end of the thermodynamics chapter for B, C and E Blocks. On the heels of yesterday's work on heat engines, cyclic thermodynamic processes and the 2nd Law of Thermodynamics, we took up the topic of entropy. Although we didn't approach it quantitatively, make sure you are clear about what entropy reflects, that entropy increases naturally in systems, how the 2nd Law of Thermodynamics relates to entropy and why we see a net increase in entropy for all processes, even if entropy is decreasing in some parts of a system. Tomorrow, E Block works on a Boyle's Lab for part of the period and starts reviewing for the remainder. B and C Blocks start on midterm review and may hit that lab later, if the midterm week time schedule permits.
F Block worked on a lab that examined pressure and volume in a sample of gas. We used the gas pressure sensor to monitor changes in pressure as we compressed a gas and used the data to document the particulars of Boyle's Law. I also made folks determine how much work was done in the process using the available P-V diagram (luckily, LoggerPro does integration). Tomorrow, we'll discuss the lab and take a look at entropy. Then its review for you guys too, so come prepared with questions!
F Block worked on a lab that examined pressure and volume in a sample of gas. We used the gas pressure sensor to monitor changes in pressure as we compressed a gas and used the data to document the particulars of Boyle's Law. I also made folks determine how much work was done in the process using the available P-V diagram (luckily, LoggerPro does integration). Tomorrow, we'll discuss the lab and take a look at entropy. Then its review for you guys too, so come prepared with questions!
1/18/12
Free For Today Only
HelloFax is letting people send free faxes to their congressional representatives and senators about SOPA and PIPA:
Stop SOPA and PIPA
Stop SOPA and PIPA
SOPA Blackout
No class-information post today to show solidarity with folks who think piracy is unethical, but that censoring the internet is a ridiculous and un-American of attacking the problem.
1/17/12
Thermodynamics!
We are going to whip through this chapter and after today, I think you see why. It is one of the most information-poor chapters in the book and the math is very simple, so it should be a 3-day trip, at best. In truth, thermodynamics is a massive physics/engineering topic, but a lot is beyond our scope, so the material is just a taste of things you'll find in later classes. Make sure to come prepared on Friday and on Monday with questions about the material for the midterm exam and if you need any practice work, ask me for some. But, you may need to give me a day to hunt up something suitable, so do not wait until the last minute...
Today we took a look at what are thermodynamic systems and how work, heat and internal energy are related in those systems. We redefined work to accommodate the properties of gases (W = PΔV) and examined P-V diagrams to evaluate how much work a thermodynamic system was doing. We also discussed the model thermodynamic processes and examples of each and then restated those using the 1st Law of Thermodynamics (ΔU = Q - W). You'll get to work with both of today's formulas in the homework problems and the questions will let you practice identifying the examples of thermodynamic processes. Tomorrow - heat engines and heat engine efficiency.
Today we took a look at what are thermodynamic systems and how work, heat and internal energy are related in those systems. We redefined work to accommodate the properties of gases (W = PΔV) and examined P-V diagrams to evaluate how much work a thermodynamic system was doing. We also discussed the model thermodynamic processes and examples of each and then restated those using the 1st Law of Thermodynamics (ΔU = Q - W). You'll get to work with both of today's formulas in the homework problems and the questions will let you practice identifying the examples of thermodynamic processes. Tomorrow - heat engines and heat engine efficiency.
1/12/12
1/11/12
Goodbye Chapter 9
Today was our final interaction with the Chapter 9 material and tomorrow will evaluate how much of that interaction was retained. B, E and F Blocks conducted a review of the material, going page by page and idea by idea through heat and temperature. C Block had that review yesterday and worked on their Heat lab activities today. That served as additional review as the ideas of heat of fusion, specific heat, direction of heat flow, the specific heat and latent heat formulas and rates of cooling were all touched upon in the investigations. The write-ups won't be due until we return from the long weekend, but most folks had time in class to get that started while working on the Newton's Law of Cooling activity. Come Tuesday, everyone will be hip deep in Thermodynamics!
1/10/12
Heat Transfer
C Block had their exam review today, which frees up tomorrow for your lab investigations. Those labs will reinforce today's review of chapter topics and give you some additional practice working with the math of the chapter. The write-up won't be due on Thursday, so don't worry about trying to get that finished while preparing for the exam.
B, E and F Blocks concentrated on mechanisms of heat transfer today. After reviewing the latent heat homework, we launched into a discussion of conduction, convection and radiation and described a number of examples of each heat transfer mechanism at work. Make sure you can define each and recognize examples of each for the test. We also looked at conductors and insulators and how they could be used to regulate heat flow into or out of a system. Again, examples were used to highlight this part of the lesson, so be able to explain an example on Thursday's exam. Tomorrow is review, so come with questions that you have about the material.
B, E and F Blocks concentrated on mechanisms of heat transfer today. After reviewing the latent heat homework, we launched into a discussion of conduction, convection and radiation and described a number of examples of each heat transfer mechanism at work. Make sure you can define each and recognize examples of each for the test. We also looked at conductors and insulators and how they could be used to regulate heat flow into or out of a system. Again, examples were used to highlight this part of the lesson, so be able to explain an example on Thursday's exam. Tomorrow is review, so come with questions that you have about the material.
1/9/12
Heat and More Heat
B and F Blocks burned through the concept of latent heat after we reviewed specific heat and how to work problems temperature change caused by energy gain and loss. Phase changes involve energy gain and loss, but without any temperature change. The substance's energy change is of the potential flavor, energy stored in the electrostatic bonds between particles, and changes in potential energy don't affect temperature. We contrasted latent heat of fusion and vaporization and explained why latent heat of vaporization will always be in a higher weight class than heat of fusion. Tomorrow we hit the idea of heat transfer before taking Wednesday as our review day for the upcoming exam.
C Block discussed the mechanisms of heat transfer - conduction, convection and radiation - and described examples of each in action. Make sure you can thoroughly discuss each method of heat transfer (when it occurs, does it need matter, is it rapid or slow) and tell what type of heat transfer is being used in specific examples. Tomorrow, we review for the chapter exam and on Wednesday you get to work on a lab that tidies up a lot of our topics on heat and temperature.
E Block conducted three small investigations that allowed folks to explore heat of fusion, heat transfer between objects at different temperatures and how temperature difference impacts the rate of heat flow between objects. You got a lot of practice working with the specific heat formula and added a new bit of math to the mix - the exponential relationship that is Newton's Law of Cooling. I put some hints on the board to use for writing your conclusion and there's plenty of information in the book and notes to flesh out your explanation of your results. We'll discuss the lab in class tomorrow, before reviewing the latent heat homework and embarking on a discussion of methods of heat transfer.
C Block discussed the mechanisms of heat transfer - conduction, convection and radiation - and described examples of each in action. Make sure you can thoroughly discuss each method of heat transfer (when it occurs, does it need matter, is it rapid or slow) and tell what type of heat transfer is being used in specific examples. Tomorrow, we review for the chapter exam and on Wednesday you get to work on a lab that tidies up a lot of our topics on heat and temperature.
E Block conducted three small investigations that allowed folks to explore heat of fusion, heat transfer between objects at different temperatures and how temperature difference impacts the rate of heat flow between objects. You got a lot of practice working with the specific heat formula and added a new bit of math to the mix - the exponential relationship that is Newton's Law of Cooling. I put some hints on the board to use for writing your conclusion and there's plenty of information in the book and notes to flesh out your explanation of your results. We'll discuss the lab in class tomorrow, before reviewing the latent heat homework and embarking on a discussion of methods of heat transfer.
1/5/12
Specific Heat
B Block took time to define heat and relate temperature change to the direction of the flow of heat energy between objects. Heat will always flow spontaneously from the object at a higher temperature to an object of lower temperature, but we have to do work on the system to move heat up a temperature gradient. Work can also be done on an object to increase its internal energy, which is why when you hit a nail with a hammer, the nail head feels nice and warm. Tomorrow, we jump into the specific heat arena and the video I'll post below will be relevant to tomorrow's homework.
For C, E and F Blocks, specific heat was the topic of the day. Specific heat is the amount of heat energy we must add or remove to change the temperature of 1 kg of a substance by 1°C. The higher the specific heat, the more energy necessary for a temperature change and the lower the specific heat, the less energy required. We looked at some examples of specific heat values in class and discussed how the specific heat differences between water, land and air contribute to the moderate climate for coastal areas. Our attention then moved to the method of determining specific heat (calorimetry) and how the basic principle behind calorimetry, aka conservation of energy, can be used to solve problems. Remember that the ΔT variable represents the difference between the final and initial temperatures and approach problems so that ΔT stays positive, even if you have to expand it to T1 = Tf (opposite of our normal pattern. For C and E Blocks, we'll go over your specific heat homework in class before moving onto the concept of latent heat. For F Block, your homework problems are due on Monday, since tomorrow is lab day!
Here is a quick and dirty video for solving a calorimetry-type problem, which requires you determine the final temperature for the system:
For C, E and F Blocks, specific heat was the topic of the day. Specific heat is the amount of heat energy we must add or remove to change the temperature of 1 kg of a substance by 1°C. The higher the specific heat, the more energy necessary for a temperature change and the lower the specific heat, the less energy required. We looked at some examples of specific heat values in class and discussed how the specific heat differences between water, land and air contribute to the moderate climate for coastal areas. Our attention then moved to the method of determining specific heat (calorimetry) and how the basic principle behind calorimetry, aka conservation of energy, can be used to solve problems. Remember that the ΔT variable represents the difference between the final and initial temperatures and approach problems so that ΔT stays positive, even if you have to expand it to T1 = Tf (opposite of our normal pattern. For C and E Blocks, we'll go over your specific heat homework in class before moving onto the concept of latent heat. For F Block, your homework problems are due on Monday, since tomorrow is lab day!
Here is a quick and dirty video for solving a calorimetry-type problem, which requires you determine the final temperature for the system:
1/4/12
The Irony
Our focus was "heat" on the coldest day of the school year, so far.
C, E and F Blocks reviewed their homework on temperature before defining heat and detailing why it was a different phenomenon than internal energy. We discussed why heat always moves spontaneously down a temperature gradient and described devices that use work to push heat energy up the gradient (air conditioners and refrigerators). The connection between heat, temperature, internal energy and work ended our time, along with an overview of how James Joule pieced together that particular puzzle. Tomorrow, we jump into the concept of specific heat and how to calculate how much heat is gained or lost by an object.
B Block started their period by reviewing yesterday's lab investigations. Mixing warm and cold water produced curved heating/cooling plots that could be explained by Newton's Law of Cooling, which proposes an exponential pattern to heat loss by an object. When the temperature differences are large, the heat transfer is rapid but as the temperatures move closer together, the rate of energy transfer slows until there is zero net transfer of energy when the system reaches thermal equilibrium. We also looked at why our calculated value for the latent heat of fusion for water was higher than expected. The water in our experiment was not pure water (regular tap water) and a portion of the energy transferred by the warm water did not go into the ice. The system was not a closed one, so the surrounding environment accepted some of the warm water's energy and those factors contributed to the inflated values for Lf, H2O. Our attention then turned to the definition of temperature and how temperature relates to an object's internal energy. The three basic temperature scales were reviewed, as were the ideas of thermal equilibrium and thermal expansion. Tomorrow, we discuss the phenomenon of heat and how it integrates with out discussions of temperature and internal energy. At the same time, we'll connect it with work.
C, E and F Blocks reviewed their homework on temperature before defining heat and detailing why it was a different phenomenon than internal energy. We discussed why heat always moves spontaneously down a temperature gradient and described devices that use work to push heat energy up the gradient (air conditioners and refrigerators). The connection between heat, temperature, internal energy and work ended our time, along with an overview of how James Joule pieced together that particular puzzle. Tomorrow, we jump into the concept of specific heat and how to calculate how much heat is gained or lost by an object.
B Block started their period by reviewing yesterday's lab investigations. Mixing warm and cold water produced curved heating/cooling plots that could be explained by Newton's Law of Cooling, which proposes an exponential pattern to heat loss by an object. When the temperature differences are large, the heat transfer is rapid but as the temperatures move closer together, the rate of energy transfer slows until there is zero net transfer of energy when the system reaches thermal equilibrium. We also looked at why our calculated value for the latent heat of fusion for water was higher than expected. The water in our experiment was not pure water (regular tap water) and a portion of the energy transferred by the warm water did not go into the ice. The system was not a closed one, so the surrounding environment accepted some of the warm water's energy and those factors contributed to the inflated values for Lf, H2O. Our attention then turned to the definition of temperature and how temperature relates to an object's internal energy. The three basic temperature scales were reviewed, as were the ideas of thermal equilibrium and thermal expansion. Tomorrow, we discuss the phenomenon of heat and how it integrates with out discussions of temperature and internal energy. At the same time, we'll connect it with work.
1/3/12
We're Back!
After a nice, long, relaxing break, we are back with our noses to the grindstone.
C, E and F Blocks began their discussion of temperature which, for most everyone, was a nice review to kick off the week. We defined temperature as the average kinetic energy of the particles in a substance and examined how translational, rotational and vibrational kinetic energies all played in a role in an object's temperature. We then turned to how temperature can change through a gain or loss of energy and how the concept of thermal equilibrium fit into this construct. With the example of how a thermometer can assess an object's temperature, we segued into the idea of thermal expansion/contraction and how it made old-timey thermometers work and was still a critical topic for engineers. We ended with an overview of the temperature scales and the promise that tomorrow will center around the idea of heat.
B Block went over their fluid mechanics exams (as did E Block), then moved into two investigations to introduce the ideas of heat, temperature, thermal equilibrium and phase change. Mixing Warm and Cold water showed the heating and cooling curves for equal masses of water combined and how they reached an equilibrium temperature intermediate between the two extremes. The heat gained and lost was calculated (Q = mcΔT) and compared to demonstrate conservation of energy. Well, as well as it could be conserved in an open calorimeter. The Latent Heat of Fusion investigation looked at the amount of heat energy needed to take water through the solid-liquid phase change. We'll hit all of these topics in detail in this chapter, but your work with in chemistry should have you with a leg up on the material. Tomorrow, temperature, thermal equilibrium and thermal expansion...
C, E and F Blocks began their discussion of temperature which, for most everyone, was a nice review to kick off the week. We defined temperature as the average kinetic energy of the particles in a substance and examined how translational, rotational and vibrational kinetic energies all played in a role in an object's temperature. We then turned to how temperature can change through a gain or loss of energy and how the concept of thermal equilibrium fit into this construct. With the example of how a thermometer can assess an object's temperature, we segued into the idea of thermal expansion/contraction and how it made old-timey thermometers work and was still a critical topic for engineers. We ended with an overview of the temperature scales and the promise that tomorrow will center around the idea of heat.
B Block went over their fluid mechanics exams (as did E Block), then moved into two investigations to introduce the ideas of heat, temperature, thermal equilibrium and phase change. Mixing Warm and Cold water showed the heating and cooling curves for equal masses of water combined and how they reached an equilibrium temperature intermediate between the two extremes. The heat gained and lost was calculated (Q = mcΔT) and compared to demonstrate conservation of energy. Well, as well as it could be conserved in an open calorimeter. The Latent Heat of Fusion investigation looked at the amount of heat energy needed to take water through the solid-liquid phase change. We'll hit all of these topics in detail in this chapter, but your work with in chemistry should have you with a leg up on the material. Tomorrow, temperature, thermal equilibrium and thermal expansion...
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