Physics 9702 · AS & A Level · The first law of thermodynamics

The first law of thermodynamics — practice question

(a(i))[1]

State the key assumption in the kinetic theory of gases that gives the result that the potential energy between the atoms of an ideal gas is zero.

(a(ii))[2]

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

(a(iii))[2]

Explain why an increase in the internal energy of an ideal gas is directly linked to a rise in the gas temperature.

(b(i))[1]

State the change in internal energy of the gas during one full cycle PQRP.

(b(ii))[2]

Calculate the work done on the gas during the change from P to Q.

(b(iii))[3]

Some energy changes in the cycle PQRP are shown in Fig. 2.2. Complete Fig. 2.2 so that every energy change is shown.

(i)[1]

State the change in internal energy of the gas during one full cycle PQRP.

(ii)[2]

Calculate the work done on the gas during the change from P to Q.

(iii)[3]

Some energy changes in the cycle PQRP appear in Fig. 2.2. Complete Fig. 2.2 so that all of the energy changes are shown.

Worked solution & mark scheme

This 17-mark question has a full step-by-step worked solution and mark scheme. One marking point: no attractive or repulsive forces between atoms/molecules/particles

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