Unit 1: Thermodynamics
Physics 2 · Unit 1 · Paper 1

Thermodynamics unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1Paper 2Paper 3
Each paper is built from this unit’s 22 terms and is the same for everyone, so a teacher can assign “Unit 1, Paper 1” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 37 min 34 points0/17 attempted
1

Heat vs temperature vs internal energy

2

Ideal gas law

3

RMS speed

4

Degrees of freedom qualitatively

5

Thermal equilibrium in mixing problems

6

Entropy and probability

7

Conduction, convection, radiation

8

Thermal expansion

9

Isothermal, isobaric, isochoric, adiabatic

10

Latent heat

11

Internal energy of an ideal gas

12

PV diagram work

Short answer 1. Define or explain: Kinetic theory and temperature

3 pts

Short answer 2. Define or explain: Ideal gas process on a PV diagram

3 pts

Short answer 3. Define or explain: Why a PV cycle's enclosed area is net work

3 pts

Short answer 4. Define or explain: Temperature vs thermal energy

3 pts

Free response

10 pts

A heat engine operates between a hot reservoir at 500 K and a cold reservoir at 300 K. In each cycle it absorbs 600 J from the hot reservoir and exhausts 400 J to the cold reservoir.

Calculate the work output per cycle and the efficiency of the engine.

Calculate the maximum possible (Carnot) efficiency for these reservoirs and state whether the engine’s performance is physically allowed.

During one leg of the cycle the working gas absorbs 500 J of heat while doing 350 J of work on the piston. Calculate the change in internal energy and state what happens to the gas temperature.

Use the second law to explain why the exhaust heat cannot be reduced to zero.

Calculate the total entropy change of the two reservoirs per cycle and explain what its sign shows.