A cyclist carries a loudspeaker that produces a steady sound with a frequency of 800 Hz. At one instant, a stationary microphone detects the sound at a frequency of 790 Hz.
Explain whether the cyclist is travelling towards or away from the microphone at this instant.
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.