An idealised thermodynamic cycle of a heat engine involves several distinct stages.
Explain what is meant by an adiabatic process.
During the compression stroke of an ideal diesel engine cycle, air is compressed adiabatically from an initial pressure of 1.0 × 105 Pa and volume V1 V_1\,V1 to a final pressure of 75 × 105 Pa and volume V2V_2V2. Taking the adiabatic index γ \gamma\,γ for air to be 1.4, calculate the compression ratio V1V2\displaystyle \frac{V_1}{V_2}V2V1.
Explain why a diesel engine requires a much higher compression ratio than a standard petrol engine.
29 exam-style questions on AQA A Level Physics Thermodynamics and engines (A-level only), covering First law of thermodynamics (A-level only), Non-flow processes (A-level only), The $p$ - $V$ diagram (A-level only), Engine cycles (A-level only), Second Law and engines (A-level only), and Reversed heat engines (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.