Section 5.2 - Thermal Exam Questions

Question 1

State the 5 assumptions made for the kinetic theory equation (5)

Answer 1

Molecules are point molecules
Molecules do not attract each other
Molecules move with continual random motion
All collisions are elastic
Time of collisions in negligible

Question 2

How is work done on a gas calculated from a pressure against volume graph?

Answer 2

Area under the graph

Question 3

Explain what is meant by specific latent heat of fusion (2)

Answer 3

The energy required to change one kg of an object from liquid to solid without changing temperature

Question 4

Water is pumped througha heater in a hot tub, why is the temperature rise greater when the pump works at a higher speed? (2)

Answer 4

The pump is doing work on the water

Work can raise the temperature of the body

Question 5

Use the kinetic theory of gases to explain why the pressure inside a football increases when the temperature of the air inside it rises. Assuming volume remains constant (3)

Answer 5

Molecules have a greater rms velocity
Number of collisions between molecules and inside surface of ball increases per second
pressure = F/A and F = rate of change of momentum