An automated survey recorded the distance and recession speed of four galaxies. Mpc is a unit of distance.
The recession speed should be proportional to the distance.
| Galaxy | Distance in Mpc | Recession speed in km/s |
|---|---|---|
| J | 18 | 1260 |
| K | 36 | 2520 |
| L | 54 | 3150 |
| M | 72 | 5040 |
Which measurement should be repeated because it does not fit the proportional relationship?
Galaxy K: 36 Mpc36\ \mathrm{Mpc}36 Mpc and 2520 km/s2520\ \mathrm{km/s}2520 km/s
Galaxy J: 18 Mpc18\ \mathrm{Mpc}18 Mpc and 1260 km/s1260\ \mathrm{km/s}1260 km/s
Galaxy M: 72 Mpc72\ \mathrm{Mpc}72 Mpc and 5040 km/s5040\ \mathrm{km/s}5040 km/s
Galaxy L: 54 Mpc54\ \mathrm{Mpc}54 Mpc and 3150 km/s3150\ \mathrm{km/s}3150 km/s
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.