Lots of Heat

Physics A worked on two labs that investigated heat transfer. In the first, the rate of heat gain/loss and the amount of heat gain/loss was tracked for two equal-mass samples of water, one hot and one cold. The second experiment had students experimentally determine the heat of fusion for water. Things to consider for your write-up:

1. What does the shape of the graphs tell you about heat transfer between substances? Was it at a constant rate? When did the heat transfer stop?
2. Would you expect the heat gained by the cold water to be the same as the heat lost by the hot water? Why or why not?
3. Why did we use two insulating cups to make the calorimeter? How could you have improved the design? Did your improved design give you better results?
4. What is the heat of fusion (definition)? Would you expect it to be the same for all materials? Why or why not?
5. Sources of error?

Physics B went over their lab work from yesterday and then dived into a discussion of temperature. We defined temperature, thermal equilibrium and thermal expansion and contrasted the three major temperature scales. Tomorrow, we'll start to look at heat energy, which is energy transferred between objects with different temperatures.

Intro Physics reviewed their work with temperature and then began to look at heat energy. We define heat energy, looked at whay heat energy always flows spontaneously from objects at higher temperatures to objects at lower temperatures and described the three methods of heat transfer: conduction, convection and radiation. Tomorrow we'll review this material and then look at specific heat.

Honors Physics reviewed their work with simple harmonic motion and then moved into adding physical descriptors to objects displaying SHM. We defined period, frequency and amplitude and discussed factors that impact period/frequency of a pendulum and mass-spring system. Tomorrow, we'll work on a lab dealing with the factors that affect the period of a simple pendulum.

Finally!

Midterm Reviews - Over
Midterm Exams - Over
Back to Work

Physics A began their work with heat and temperature today with a defining of temperature and its relationship to internal energy. We then looked at thermal expansion and the various temperature scales commonly in use in both daily life and the scientific community. Intro Physics did the same thing, but without the internal energy piece. Tomorrow, Physics A works on a series of lab investigations for heat transfer and how it impacts temperature change and phase change. Intro Physics will finish up with temperature and then begin to take a look at heat energy.

Physics B worked on two lab investigations during the long block. The first examined heat transfer between two substances at different temperatures and used that information to calculate the specific heat of water. The graphs produce by mixing the hot and cold water were mirror images and the amount of heat lost by the hot water and the heat gained by the cold water were quite similar and that is what we would predict based on conservation of energy. The second lab looked at the heat of fusion of water, the amount of heat energy required to promote a solid-liquid phase change. Tomorrow, we'll dig deeper into the temperature and temperature change part of these experiments and heat heat energy starting on Thursday.

Honors Physics began their work with vibrations and waves. We contrasted periodic motion with simple harmonic motion and looked at how Hooke's Law is used to calculate the restoring force of a spring. We also looked at how to calculate the restoring force of a pendulum and detailed the changes in restoring force, acceleration, velocity and energy for both mass-spring systems and pendulums. Tomorrow, we'll look at quantifying SHM through period, frequency and amplitude and that will lead us to our lab on Thursday, which will center on pendulum motion.

A Change!

The first day of midterms arrived with much fanfare and to do. There were also, perhaps, shenanigans and goings-on, but I won't admit to anything.

G Block had their midterm today, with tomorrow being the day the axe fell for B and E Blocks. Unless I've talked to you individually, make sure you have your review material ready to turn in. Also - CALCULATORS! Do not forget your means of mathematical manipulation. Any last-minute questions can be emailed today (all lines of communication cease at 9:00 pm) or taken up before school tomorrow. A Block is on deck Wednesday, so read the above and that applies for you, too.

Good luck everyone!

No Changes

Everyone's still working on reviewing for their midterms. Remember that the exam is 10% of your year's grade, so take every opportunity you're given to do your best.

Here's a comic... makes you think about those pesky advertisements...

Midterm Review

Midterms are next week and everyone is currently in the review process. Individuals are working on self-paced review material, getting help in class for topics that are still troubling them. Remember to use all available resources to prepare for next week - old tests, notes, PowerPoint packets, labs, worksheets, homework, etc. Any video I have previously posted is still available and if there are others you would like me to make, let me know and I can get that done.

2-D Motion Review Videos

I posted these awhile back, but they might be useful now, with midterms looming...

Counting Down to Midterms

Physics A and B worked on correcting their Fluid Mechanics exams and will start on reviewing for midterm exams tomorrow. I'll give you old chapter tests for the units we've covered and we'll work on them in class so you can get help with the questions. You have all of your old tests for this year, your note packs and worksheets, as well as your labs for review so make sure to draw all of that together and organize it to make your study experience efficient.

Intro Physics completed their Work and Energy exams and will start on midterm review tomorrow. Start gathering your old work and organize it in a way that is meaningful to you. I'll give you review material, but if there is a topic on which you know you need extra help, see me for additional review material or to schedule a time to get one-on-one help.

Honors Physics went over their Thermodynamics tests before beginning on the review work for the midterm exam. This packet covers chapters 1 and 2 and you will get material for chapters 3-10 as we go along. Don't hesitate to ask for anything else you might require for review, but do it in a timely fashion. If you're asking the day before the midterm, you're not really helping yourself very much...

Loads of Tests!

Physics A and B, as well as Intro Physics had their chapter tests today, though Intro Physics had the unexpected bonus of a Code Blue drill that stole a good 15 minutes from their testing period. We'll have to finish up tomorrow, but that won't be a problem...

Honors Physics conducted a lab investigation targeting the topic of heat engines. The impact of heat and work on a thermodynamic system was modeled for a 4-cycle and 3-cycle heat engine, with the resulting PΔV diagrams analyzed for work done by the system. It was clear how each thermodynamic process (isothermal, adiabatic, etc.) was involved in the system. We'll discuss the lab tomorrow, review the thermodynamic exams and then turn attention to the upcoming midterm exam period.

Videos

Loose Ends Getting Tied

Physics A Block reviewed their lab work from yesterday and the chapter concepts for tomorrow's exam. Physics B Block conducted their investigations and had time for additional review for tomorrow's exam. Come ready tomorrow with calculators and see me before school if you have any additional questions.

Intro Physics reviewed their work, power and energy problems and then the general chapter concepts for tomorrow's exam. Come prepared with calculators and see me before school if you have any additional questions.

Honors Physics enjoyed their thermodynamics exam today and will conduct a lab investigation about heat engines tomorrow during long block.

Getting Read for Tests

This week has a test for every class and today was spent starting to get ready for them...

Physics A reviewed Bernoulli's Principle and Bernoulli's equation before walking through the chapter to highlight the topics and formulas relevant for Wednesday's exam. Tomorrow is a series of activities to demonstrate Bernoulli's principle and there will also be time for additional review.

Physics B did the above, but reversed. Yeah... so that's about it...

Intro Physics discussed conservation of mechanical energy and the concept of efficiency. It may be unpleasant, but not all energy put into a system, physical or biological, comes out in the form of useful work or energy. Some is always converted to a form not usable in the current circumstances. Therefore a measure of work output/work input or energy output/energy input will always come out as less than one. That is a measure of the efficiency of system, therefore it can be said that efficiencies of real systems will never be 100% and even theoretical/non-friction systems could ever exceed 100%. That would be a blatant violation of conservation of energy and the universe does not hold with nonsense like that. Class ended with more practice for work, energy and power which we will review tomorrow as part of our general review for Wednesday's exam.

Honors Physics reviewed their work with the 2^nd Law of Thermodynamics and heat engine efficiency before walking through the chapter as part of a general review for tomorrow's exam. I'm there before school tomorrow if you have any last-minute questions.

Ending Up in Good Places

Physics A and B completed their work for fluid mechanics with an overview of Bernoulli's principle and Bernoulli's equation. Bernoulli's principle states that pressure and velocity in a fluid are inversely related and it is the pressure differences that create a net force that accelerates fluids. We discussed examples such as smoke rising up a chimney and the attacking shower curtain and you'll get to look at some more examples next week. Bernoulli's equation documents conservation of energy in fluid systems and is a handy relationship for finding information about pressure, speed or height of a fluid if the conditions in another part of the system are known. The problems for homework do take some thought, but be mindful of the hints you were provided and here's one more: If the velocities of two sections are incredibly different, so that one area is moving incredibly slowly compared to the other area, it is not inappropriate to set the velocity of the slower section to zero...

Intro Physics started working on some problems for conservation of energy, stemming from yesterday's investigation. Keep in mind that energy can be all of one type or a blend, but the total energy with which you begin is the total energy with which you end. We'll go over those problems tomorrow and discuss the concept of efficiency and conservation of mechanical energy (which some of your problems address, also).

Honors Physics discussed the 2^nd law of thermodynamics and how it relates to heat engines and entropy. We looked at calculating heat engine efficiency and examples of entropy increase and decrease in systems and selected part of systems. On Monday, we'll review the chapter and Tuesday is our exam for thermodynamics.

And We're Back...

And everyone is just overjoyed about that fact...

Physics A and B have been working on describing fluids in terms of pressure changes with position in a fluid and how fluids in motion demonstrate conservation of mass. Building on the lab work conducted before break, folks generated the formula for calculating fluid pressure at any position in a fluid column and yesterday we discussed how those pressure differences arise and how they, in turn, give rise to buoyant forces. The fluids we discussed, however, were still fluids. When fluids are set in motion, the model is more complicated, though we do simplify things by working under the ideal-fluid model for our fluid-flow analyses. We discussed the properties of idea fluids and ventured into how fluids in motion demonstrate conservation of energy. In a closed fluid system, the flow rate remains constant, whether reported in mass/time or volume/time. For idea fluids, the density remains constant, so either of those two reporting units (kg/s or m³/s) document that the amount of fluid moving through a pipe remains constant. Since the produce of area (m²) and velocity (m/s) result in the unit of m³/s, that formula is useful for calculating flow rate. Therefore Av is constant or Av = Av for any two sections of pipe. Tomorrow, we'll add pressure to the mix with Bernoulli's principle.

Intro Physics have been examining the law of conservation of energy. In yesterday's lab, conversions between kinetic/gravitational potential and kinetic/elastic potential were examined to show that patters of energy change of one type were matched by energy changes in the other type to keep the total energy in the system constant. Today, we added some math to that relationship and saw how conservation of energy can be useful for problem solving where kinematics may give us a headache. Tomorrow, we'll look at why, even though conservation of total energy is inviolate, conservation of mechanical energy isn't.

Honors Physics started their quick unit on thermodynamics. Work for a thermodynamics system was defined as the product of pressure and volume change. No volume change, no work done on or by a gas. We assigned sign conventions to work and defined specific thermodynamic processes. Today, time was taken to look more closely at those processes in terms of internal energy change, work and heat and how cyclic processes fit into the picture, using heat engines and refrigeration systems as examples.