IB Physics Topic 3: Thermal Physics

The fraction of the internal energy that is due to molecular vibration varies in the different states of matter. What gives the order from highest fraction to lowest fraction of internal energy due to molecular vibration?

• liquid > gas > solid

• solid > liquid > gas

• solid > gas > liquid

• gas > liquid > solid

A liquid is initially at its freezing point. Energy is removed at a uniform rate from the liquid until it freezes completely.

Which graph shows how the temperature T of the liquid varies with the energy Q removed from the liquid?

• 
• 
• 
• 

Energy is supplied at a constant rate to a fixed mass of a material. The material begins as a solid. The graph shows the variation of the temperature of the material with time.

The specific heat capacities of the solid, liquid and gaseous forms of the material are c_s c_l and c_g respectively. What can be deduced about the values of c_s c_l and c_g?

• c_s > c_g > c_l

• c_l > c_s > c_g

• c_l > c_g > c_s

• c_g > c_s > c_l

Which of the following is numerically equal to the specific heat capacity of the substance of a solid body?

• The thermal energy required to melt the body

• The thermal energy required to increase the temperature of unit mass of the body by 1K

• The thermal energy required to increase the temperature of the body by 1K

• The total kinetic and potential energy of all the molecules in the body

Which of the following is equivalent to a temperature of –100°C?

• –373 K

• –173 K

• 173 K

• 373 K

A fixed mass of water is heated by an electric heater of unknown power P. The following quantities are measured

I. mass of water

II. increase in water temperature

III. time for which water is heated.

In order to calculate P, the specific heat capacity of the water is required. Which are also required?

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

A sealed container contains water at 5 °C and ice at 0 °C. This system is thermally isolated from its surroundings. What happens to the total internal energy of the system?

• It remains the same.

• It decreases.

• It increases until the ice melts and then remains the same.

• It increases.

Tags

NGSS.HS-PS3-4

A fixed mass of an ideal gas in a closed container with a movable piston initially occupies a volume V. The position of the piston is changed, so that the mean kinetic energy of the particles in the gas is doubled and the pressure remains constant.

What is the new volume of the gas?

• $\frac{V}{4}$

• $\frac{V}{2}$

• $2V$

• $4V$

Tags

NGSS.HS-PS3-2

Under what conditions of density and pressure is a real gas best described by the equation of state for an ideal gas?

• Low density and low pressure

• Low density and high pressure

• High density and low pressure

• High density and high pressure

A substance that is originally a solid is heated strongly for some time.
At one stage, the energy given to the substance is used as latent heat of vaporisation. At this stage, what change does the energy cause? 

• It breaks the bonds holding the molecules together. Molecules escape from the liquid. 
• It breaks the bonds holding the molecules together. The solid becomes liquid. 
• It makes the molecules move faster but there is still a strong attraction between them. 
• It makes the molecules move faster and so the temperature rises. 

Tags

NGSS.MS-PS1-4