A test vehicle carries a loudspeaker that emits sound at a constant frequency of 680 Hz. The vehicle moves along a straight track between two stationary microphones, P and Q.
The speed of sound in air is 340 m/s.
The table shows the wavelength measured by each microphone at one instant.
| Microphone | Observed wavelength in m |
|---|---|
| P | 0.48 |
| Q | 0.52 |
Calculate the observed frequency of the sound at each microphone.
Explain which microphone the vehicle is moving towards.
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.