An underwater vehicle carries a sound transmitter that emits a constant frequency. A fixed receiver monitors the transmitter during several stages of the journey. The vehicle moves directly towards or directly away from the receiver during each stage.
During stage X, the observed frequency is lower than the emitted frequency. The difference between the emitted and observed frequencies is greater during stage X than during any other stage.
Which identifies how the vehicle is moving during stage X?
Away from the receiver at the lowest speed
Towards the receiver at the lowest speed
Towards the receiver at the greatest speed
Away from the receiver at the greatest speed
94 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift, covering 7.2.1 Big Bang and Steady State theories, 7.2.2 Evidence for the Big Bang, 7.2.3 The Doppler effect and red-shift, 7.2.4 Red-shift as evidence for an expanding Universe, and 7.2.5 The CMB and the accepted model. Each one has a worked solution and a mark scheme showing where the marks go.