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A-Level CAIE Physics A216.1 Internal energyQuestion Bank

16.1 Internal energy

Question 2

[Maximum number: 3]

A cylinder contains 5.12 mol of an ideal gas at pressure 5.60×105 Pa5.60 \times 10^{5} \mathrm{~Pa} and volume 3.80×10−2 m33.80 \times 10^{-2} \mathrm{~m}^{3}.

Question 2(b)

(a)

The average kinetic energy EKE_{\mathrm{K}} of a molecule of the gas is given by the expression

EK=32kTE_{\mathrm{K}}=\frac{3}{2} k T

where k is the Boltzmann constant and T is the thermodynamic temperature.
The gas is heated at constant pressure so that its temperature rises by 125 K .

[ 3 ]

Question 2(b)(ii)

(i)

Calculate the increase in internal energy of the gas. Explain your working.

[ 3 ]

Question 2

[Maximum number: 2]

the rate h of thermal energy gained by the ice from the surroundings.

h=

W

Question 2(a)

(a)

State what is meant by internal energy.

[ 2 ]

Question 2

Question 2(a)

Question 2(a)(i)

(a)
(i)

State what is meant by the internal energy of a system.

[ 2 ]

Question 2

[Maximum number: 3]

A constant mass of an ideal gas has a volume of 3.49×103 cm33.49 \times 10^{3} \mathrm{~cm}^{3} at a temperature of 21.0∘C21.0^{\circ} \mathrm{C}. When the gas is heated, 565 J of thermal energy causes it to expand to a volume of 3.87×103 cm33.87 \times 10^{3} \mathrm{~cm}^{3} at 53.0∘C53.0^{\circ} \mathrm{C}. This is illustrated in Fig.2.1.

Fig. 2.1

Fig. 2.1

Question 2(c)

(a)

Explain why the change in kinetic energy of the molecules of this ideal gas is equal to the change in internal energy.

[ 3 ]

Question 2

[Maximum number: 4]

the period of Deimos in its orbit about Mars.
period = hours

Question 2(c)

Question 2(c)(i)

(a)
(i)

State what is meant by the internal energy of a substance.

[ 2 ]

Question 2(c)(ii)

(ii)

Use the equation in (b)(ii) to explain that, for an ideal gas, a change in internal energy ΔU\Delta U is given by

ΔU∝ΔT\Delta U \propto \Delta T

where ΔT\Delta T is the change in temperature of the gas.

[ 2 ]

Question 2

[Maximum number: 3]

electric potential energy.
energy = J

Question 2(c)

(a)

Helium-4 may be assumed to behave as an ideal gas.

A cylinder has a constant volume of 7.8×103 cm37.8 \times 10^{3} \mathrm{~cm}^{3} and contains helium-4 gas at a pressure of 2.1×107 Pa2.1 \times 10^{7} \mathrm{~Pa} and at a temperature of 290 K .

Calculate, for the helium gas,

[ 3 ]

Question 2(c)(iii)

(i)

the total internal energy.
internal energy = J

[ 3 ]

Question 2

[Maximum number: 4]

A student suggests that, when an ideal gas is heated from 100∘C100^{\circ} \mathrm{C} to 200∘C200^{\circ} \mathrm{C}, the internal energy of the gas is doubled.

Question 2(a)

Question 2(a)(i)

(a)
(i)

State what is meant by internal energy.

[ 2 ]

Question 2(b)

(b)

State and explain whether the student's suggestion is correct.

[ 2 ]

Question 2

Question 2(a)

(a)

By referring to both kinetic energy and potential energy, explain what is meant by the internal energy of an ideal gas.

[ 2 ]

Question 2

Question 2(c)

(a)

A negative temperature coefficient thermistor may be used as a type of resistance thermometer.

State one way in which the variation with temperature of the resistance of a thermistor differs from that of a platinum wire.

[ 1 ]

Question 2

[Maximum number: 1]

A fixed mass of an ideal gas has a volume V and a pressure p.
The gas undergoes a cycle of changes, X to Y to Z to X, as shown in Fig. 2.1.

Fig. 2.1

Fig. 2.1

Table 2.1 shows data for p, V and temperature T for the gas at points X, Y and Z .

Table 2.1

Table 2.1

Question 2(a)

(a)

State the change in internal energy ΔU\Delta U for one complete cycle, XYZX .

ΔU=\Delta U=
[ 1 ]
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