IB Physics HL B.4.13 Carnot efficiency limit Question Bank

Practise IB Physics HL B.4.13 by applying carnot efficiency limit 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]

The p V diagram shows a heat engine cycle consisting of adiabatic, isothermal and isovolumetric parts. The working substance of the engine is an ideal gas.

Figure for Question B.4.13 (HL)—Carnot efficiency limit question 1 — IB Physics HL

The following data are available:

\begin{aligned} & p_{\mathrm{A}}=5.00 \times 10^{5} \mathrm{~Pa} \\ & V_{\mathrm{A}}=2.00 \times 10^{-3} \mathrm{~m}^{3} \\ & T_{\mathrm{A}}=602 \mathrm{~K} \\ & p_{\mathrm{B}}=3.00 \times 10^{4} \mathrm{~Pa} \\ & p_{\mathrm{C}}=4.60 \times 10^{3} \mathrm{~Pa} \end{aligned}

The highest and lowest temperatures of the gas during the cycle are 602 K and 92 K .

The efficiency of this engine is about 0.6 . Outline how these data are consistent with the second law of thermodynamics.

$e_{\mathrm{C}}=1-\frac{92}{602}=0.847$

this engine has $e<e_{\mathrm{c}}$ as it should

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B.4.13 (HL)—Carnot efficiency limit question 1