Ch3 - Thermal Physics

1. A solid piece of tungsten melts into liquid without a change in temperature. Which of the following is correct for the molecules in the liquid phase compared with the molecules in the solid phase?

• A
• B
• C
• D

2. A heater of constant power heats a liquid of mass m and specific heat capacity c. The graph below shows how the temperature of the liquid varies with time.

• A
• B
• C
• D

3. The energy of the molecules of an ideal gas is

• A. thermal only.
• B. thermal and potential.
• C. potential and kinetic.
• D. kinetic only.

4. Two objects are in thermal contact with each other. Which of the following will determine the direction of the transfer of thermal energy between the bodies?

• A. The mass of each body
• B. The area of contact between the bodies
• C. The specific heat capacity of each body
• D. The temperature of each body

5. The mole is defined as

• A. 1/12 the mass of an atom of the isotope carbon-12.
• B. the amount of a substance that contains as many elementary entities as the number of atoms in 12 g of the isotope carbon-12.
• C. the mass of one atom of the isotope carbon-12.
• D. the amount of a substance that contains as many particles as the number of nuclei in 12 g of the isotope carbon-12.

6. A gas is contained in a cylinder by a piston. The gas is compressed rapidly by moving the piston in the direction shown. The best explanation for the resulting increase in temperature of the gas is that the molecules of the gas gain kinetic energy

• A. from the moving piston.
• B. by colliding more frequently with each other.
• C. by being pushed closer together.
• D. by colliding more frequently with the walls of the cylinder.

7. A box that is at rest with respect to horizontal ground contains a fixed quantity of an ideal gas. The internal energy of the gas is U and its temperature is T. The box is now made to move at constant speed with respect to the ground. Which of the following gives the change, if any, in the internal energy and the temperature of the gas after the box has been moving for some time?

• A
• B
• C
• D

8.

• A
• B
• C
• D

9. For two objects to be in thermal equilibrium they must

• A. be in contact with each other.
• B. radiate equal amounts of power.
• C. have the same thermal capacity.
• D. be at the same temperature.

10. A system consists of an ice cube placed in a cup of water. The system is thermally insulated from its surroundings. The water is originally at 20 °C. Which graph best shows the variation of total internal energy U of the system with time t?

• A
• B
• C
• D