Essential Question: How does thermal energy flow?
GOALS: SWBAT...
1. Draw correct phase diagrams for thermodynamics scenarios
2. Use specific heat, latent heat of fusion, & latent heat of vaporization to solve problems
3. Define the four Laws of Thermodynamics
WARM-UP 114 (4 min)
1. Copy the phase change diagram from the board, or from minute 2:20 from this video (https://www.youtube.com/watch?v=xf8O6ZaIPtw).
2. Label each of the five sections as
- liquid
- solid
- gas
- melting/freezing
- vaporizing/condensing?
3. label the three sections where temperature is changing
CLASSWORK
1. 114A. Understanding Phase Change Diagrams
Building on the warm up...
1. label the axes of your phase change diagram (it's a graph, so the vert and horiz parts represent something)
2. why is the phase change diagram horizontal during melting/freezing, and again during vaporization/condensing?
2. 114B: Problem Solving
1. Equal masses of aluminum and lead are at the same 100*C temperature. Both are placed on a block of ice. Which metal melts more ice? Why?
2. Two blocks (A & B) of lead have the same temperature. Block B has twice the mass of Block A. They are dropped into identical (same size/mass/temperature) cups of water. Will the two cups of water have the same temperatures once equilibrium is achieved? Explain in a sentence or two.
3. Explain why fruit growers spray their trees with liquid water to protect the fruit from freezing when frost is expected.
4. Solve: How much heat is needed to raise the temperature of 5.0kg of liquid water from 4.5*C to 83.0*C?
5. Solve: How much heat must be added to 10.0kg of ice at -20.0*C to convert it to steam at 120.0*C? Draw a phase diagram of this process. How many steps are there? Think about which are temperature change steps, and which are phase change, then solve each sub-problem.
3. 114C: The Laws of Thermodynamics
1. Watch the following video, and define each of the Laws of Thermodynamics
https://www.youtube.com/watch?v=_Ox6o8y46eQ
2. Which law is similar to conservation of energy?
3. For the heat engine (car engine - 5 steps), where does the heat come from, and what does the resulting expanding gases do work on?
4. Does the water in the ocean have thermal energy? If it does, why can't some of that energy be used to prime a pump so we can use that energy for our own uses (lights, etc)
5. Would it be nice if a perpetual motion machine worked? Why?
6. So, why doesn't a perpetual motion machine work?
Exit Questions
1. Would you be surprised if you heated one end of a metal spoon, and the entire spoon became uniformly hot?
2. Would you be surprised if a metal spoon, sitting on the table, became extremely hot at one end, and ice cold at the other?
3. Which law of thermodynamics would this scenario violate?
LEARNING AT HOME (HW)
**period 1 and 2 ended class a bit behind - you'll need to finish 114C and the exit questions**
114D: Entropy
1. Define "Entropy"
2. Give three examples of entropy that make sense to you as a high school aged person (AKA, don't write something super complex that you don't understand)
Essential Question: What is Heat?
GOALS: SWBAT...
1. define entropy
2. answer thermo related questions and define thermo terms
WARM-UP 114 (4 min)
1.can you warm your house by using the oven?
2. should you? Why yes or why no?
3. can you cool your house by using the open refrigerator?
4. Should you?
CLASSWORK
1. Review 114A: Entropy
Definition: a measure of the level of disorder. Greater disorder = greater entropy. Also, objects with greater entropy are generally less able to do work. Example: Air. In what state is air? Is air a good conductor (aka, can it pass energy from one object to another)?
examples (wood+fire=ash; solid water+heat=liquid water; energy+popcorn kernels=popcorn)
Common Quote: "The universe tends towards disorder"
2. 114B: How Does a Refrigerator Work?
https://www.youtube.com/watch?v=EIP3pSio7-M
Consider the following for your notes
1. How does heat flow during evaporation (similar to vaporization)?
2. How does heat flow during condensation?
3. What does the expansion device do to the refrigerant?
4. The cool refrigerant flows through the refrigerator and absorbs heat. Which Law of Thermodynamics does this heat flow illustrate?
5. What is the function of the coils on the back of the refrigerator?
3. 114C: Knowledge Inventory Revisit: Post-Learning
Return to Day 101 in your notes, cover up your answers on the pre-learning side, and re-answer the 20 questions we attempted at the very beginning of this unit. Don't look up the answers. This is still a test to see what you know and what you don't know.
Lost the questions? Here's the link: https://sites.google.com/site/mralexandersscienceweb/physics/daily-agenda-classwork/day-101
LEARNING AT HOME (HW)
Exam Thursday. Review Days 101-113
States of Matter Lab is due Wednesday 11:59pm
What are we doing this week?
Ending Thermodynamics. beginning a review of modeling Conservation of Energy, and of Simple Machines.
You: What are simple machines?
Me: https://www.youtube.com/watch?v=Av07QiqmsoA
Also me: https://www.youtube.com/watch?v=3jQXN8SMewo
Tues: Entropy/Knowledge Inventory revisit
Wed: exam review
Thurs: exam
Fri: Screw, Incline, etc (6 components). Define. explain how each works. Give examples. Put info graphic organizer
Next week: Make Rube Goldberg Machines in groups