Free Printable IB Physics Topic 3 Thermal Physics

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IB Physics Topic 3 Thermal Physics

Total questions: 20

Worksheet time: 20mins

Name

Class

Date

The graph shows how the temperature of a liquid varies with time when energy is supplied to the liquid at a constant rate P. The gradient of the graph is K and the liquid has a specific heat capacity c.

What is the mass of the liquid?

$\frac{P}{cK}$

$\frac{PK}{c}$

$\frac{Pc}{K}$

$\frac{cK}{P}$

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 mass m of ice at a temperature of –5 °C is changed into water at a temperature of 50 °C.

Specific heat capacity of ice = c_i

Specific heat capacity of water = c_w

Specific latent heat of fusion of ice = L

Which expression gives the energy needed for this change to occur?

55 m c_w + m L

55 m c_i + 5 m L

5 m c_i + 50 m c_w + m L

5 m c_i + 50 m c_w + 5 m L

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

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.

10.

A pure solid is heated at its melting point. While it is melting the

mean kinetic energy of the molecules of the solid increases.

mean potential energy of the molecules of the solid increases.

temperature of the solid increases.

temperature of the solid decreases.

11.

A sealed cylinder of length l and cross-sectional area A contains N molecules of an ideal gas at kelvin temperature T.

What is the force acting on the area of the cylinder marked A due to the gas?

$\frac{NRT}{l}$

$\frac{NRT}{lA}$

$\frac{Nk_BT}{lA}$

$\frac{Nk_BT}{l}$

12.

A fixed mass of an ideal gas is trapped in a cylinder of constant volume and its temperature is varied. Which graph shows the variation of the pressure of the gas with temperature in degrees Celsius?

13.

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?

$\frac{V}{4}$

$\frac{V}{2}$

$2V$

$4V$

14.

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

15.

Which of the following is not an assumption of the kinetic model of ideal gases?

All particles in the gas have the same mass.

All particles in the gas have the same speed.

The duration of collisions between particles is very short.

Collisions with the walls of the container are elastic.

16.

What is the definition of the mole?

The amount of substance that has the same mass as 6.02 × 10²³ atoms of carbon-12.

The amount of substance that contains as many nuclei as the number of nuclei in 12 g of carbon-12.

The amount of substance that has the same mass as one atom of carbon-12.

The amount of substance that contains as many elementary entities as the number of atoms in 12 g of carbon-12.

17.

An ideal gas is contained in a thermally insulated cylinder by a freely moving piston.

The gas is compressed by the piston and as a result the temperature of the gas increases. What is the explanation for the temperature rise?

The rate of collision between the molecules increases.

Energy is transferred to the molecules by the moving piston.

The molecules of the gas are pushed closer together.

The rate of collision between the molecules and the walls of the cylinder increases.

18.

The energy of the molecules of an ideal gas is

thermal only.

thermal and potential.

potential and kinetic.

kinetic only.

19.

The volume of an ideal gas in a container is increased at constant temperature. Which of the following statements is/are correct about the molecules of the gas?

I. Their average speed remains constant.

II. The frequency of collisions of molecules with unit area of the container wall decreases.

III. The force between them decreases.

I only

I and II only

I and III only

II and III only

20.

A partially-inflated balloon is placed inside a bell jar. The bell jar is connected to an air pump. The air pump is switched on and air is removed from the bell jar.
What happens to the pressure and to the volume of the gas inside the balloon?

pressure decreases
volume decreases

pressure decreases
volume increases

pressure increases
volume decreases

pressure increases
volume increases

100 %

IB Physics Topic 3 Thermal Physics

Total questions: 20

Worksheet time: 20mins

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