Free Printable Unit 3 Thermal Physics

1.

Energy is transferred to water in a flask at a rate P. The water reaches boiling point and then P is increased. What are the changes to the temperature of the water and to the rate of vaporization of the water after the change?

a)

A

b)

B

c)

C

d)

D

2.

Boiling water is heated in a 2 kW electric kettle. The initial mass of water is 0.4 kg. Assume the specific latent heat of vaporization of water is 2 MJ kg^–1.

What is the time taken for all the water to vaporize?

a)

250 s

b)

400 s

c)

2500 s

d)

4000 s

3.

A gas storage tank of fixed volume V contains N molecules of an ideal gas at temperature T. The pressure at kelvin temperature T is 20 MPa.
$\frac{N}{4}$ molecules are removed and the temperature changed to 2T. What is the new pressure of the gas?

a)

10 MPa

b)

15 MPa

c)

30 MPa

d)

40 MPa

4.

A substance changes from the solid phase to the gas phase without becoming a liquid and without a change in temperature.

What is true about the internal energy of the substance and the total intermolecular potential energy of the substance when this phase change occurs?

a)

A

b)

B

c)

C

d)

D

5.

The temperature of a fixed mass of an ideal gas changes from 200 °C to 400 °C.What is
$\frac{mean\ kinetic\ energy\ of\ gas\ at\ 200\degree C}{mean\ kinetic\ energy\ of\ gas\ at\ 400\degree C}$

a)

0.50

b)

0.70

c)

1.4

d)

2.0

6.

A liquid of mass m and specific heat capacity c cools. The rate of change of the temperature of the liquid is k. What is the rate at which thermal energy is transferred from the liquid?

a)

$\frac{mc}{k}$

b)

$\frac{k}{mc}$

c)

$\frac{1}{kmc}$

d)

$kmc$

7.

A 700 W electric heater is used to heat 1 kg of water without energy losses. The specific heat capacity of water is 4.2 kJ kg^–1 K^–1. What is the time taken to heat the water from 25 °C to 95 °C?

a)

7 s

b)

30 s

c)

7 minutes

d)

420 minutes

8.

A container is filled with a mixture of helium and oxygen at the same temperature. The molar mass of helium is 4 g mol–1 and that of oxygen is 32 g mol–1.What is the ratio $\frac{average\ speed\ of\ helium\ molecules}{average\ speed\ of\ oxygen\ molecules}$

a)

$\frac{1}{8}$

b)

$\frac{1}{\sqrt{8}}$

c)

$\sqrt{8}$

d)

$8$

9.

Container X contains 1.0 mol of an ideal gas. Container Y contains 2.0 mol of the ideal gas. Y has four times the volume of X. The pressure in X is twice that in Y.
What is
$\frac{temperature\ of\ gas\ inX}{temperature\ ofgas\ inY}$ ?

a)

$\frac{1}{4}$

b)

$\frac{1}{2}$

c)

1

d)

2

10.

A solid substance has just reached its melting point. Thermal energy is supplied to the substance at a constant rate. Which graph shows the variation of the temperature T of the substance with energy E supplied?

a)

A

b)

B

c)

C

d)

D

11.

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?

a)

A

b)

B

c)

C

d)

D

12.

$\frac{specific\ heat\ capacity\ of\ copper}{specific\ latent\ heat\ of\ vaporisation\ of\ copper}\$

What are the units of the ratio ?

a)

no units

b)

K

c)

$K^{-1}$

d)

$K^{-2}$

13.

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?

a)

$\frac{NRT}{l}$

b)

$\frac{NRT}{lA}$

c)

$\frac{Nk_bT}{lA}$

d)

$\frac{Nk_bT}{l}$

14.

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?

a)

It remains the same.

b)

It decreases.

c)

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

d)

It increases.

15.

A container that contains a fixed mass of an ideal gas is at rest on a truck. The truck now moves away horizontally at a constant velocity. What is the change, if any, in the internal energy of the gas and the change, if any, in the temperature of the gas when the truck has been travelling for some time?

a)

A

b)

B

c)

C

d)

D

Unit 3 Thermal Physics

Total questions: 15

Worksheet time: 30mins

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