IB Physics HL B.4.12 Heat engine efficiency Question Bank

Practise IB Physics HL B.4.12 by applying heat engine efficiency concepts to exam-style physics questions.

Exam points

identify the relevant physical quantity, model or diagram
apply the correct equation and units to the evidence
justify the result using conservation laws, forces or energy relationships

[Maximum number: 2]

This question is in two parts. Part 1 is about simple harmonic motion (SHM). Part 2 is about gas in an engine.

Part 1 Simple harmonic motion (SHM)
An object is placed on a frictionless surface. The object is attached by a spring fixed at one end and oscillates at the end of the spring with simple harmonic motion (SHM).

Figure for Question B.4.12 (HL)—Heat engine efficiency question 1 — IB Physics HL

The tension F in the spring is given by F=k x where x is the extension of the spring and k is a constant.

The shaded area WXYZ is 610 J . The total thermal energy transferred out of the gas in one cycle is 1.3 kJ .

Determine the efficiency of cycle WXYZ.

efficiency $=\frac{610}{1300}$ ;
0.47 or 47 %;

Marking guidance:

Award [2] for a bald correct answer.
Award [1] for $\frac{610}{(610+1300)}=0.32$ .
Award [0] for any fraction that would exceed 1 even if later fudged.
Award [0] for efficiency $=\frac{T_{C}-T_{H}}{T_{H}}=38 \%$ , question does not imply that this is a Carnot cycle.

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B.4.12 (HL)—Heat engine efficiency question 1