Physics Thermodynamics 3

Question 1

According to the zeroth law of thermodynamics, if A is in thermal equilibrium with B, and B is in thermal equilibrium with C, then:

Accepted Answer

A and C are in thermal equilibrium

Answer

The zeroth law states that thermal equilibrium is transitive: A and C must also be in thermal equilibrium.

Question 2

Which statement best describes the third law of thermodynamics?

Accepted Answer

The entropy of a perfect crystal approaches zero as temperature approaches absolute zero

Answer

The third law states that as T → 0 K, the entropy of a pure perfect crystal approaches zero.

Question 3

In a P-V diagram, the area enclosed by a cyclic process represents:

Accepted Answer

The net work done by the system

Answer

The enclosed area on a P-V diagram equals the net work done by the system per cycle.

Question 4

An ideal gas undergoes an isochoric (constant volume) process. Which of the following is true?

Accepted Answer

No work is done on or by the gas

Answer

At constant volume, ΔV = 0, so W = PΔV = 0; no work is done.

Question 5

The specific heat capacity at constant pressure (Cp) is always _____ the specific heat capacity at constant volume (Cv) for an ideal gas.

Accepted Answer

Greater than

Answer

Cp = Cv + R for an ideal gas, because at constant pressure extra energy goes into doing work on the surroundings.

Physics Practice Test