An astronomer plots recession speed on the vertical axis and distance on the horizontal axis. The line passes through the origin and the point (80 Mpc, 6000 km/s)(80\ \mathrm{Mpc},\ 6000\ \mathrm{km/s})(80 Mpc, 6000 km/s).
Which gives the gradient and the trend it represents?
0.0133 km s−1 Mpc−10.0133\ \mathrm{km\,s^{-1}\,Mpc^{-1}}0.0133 kms−1Mpc−1; speed increases with distance.
75 km s−1 Mpc−175\ \mathrm{km\,s^{-1}\,Mpc^{-1}}75 kms−1Mpc−1; speed decreases with distance.
75 km s−1 Mpc−175\ \mathrm{km\,s^{-1}\,Mpc^{-1}}75 kms−1Mpc−1; speed increases with distance.
0.0133 km s−1 Mpc−10.0133\ \mathrm{km\,s^{-1}\,Mpc^{-1}}0.0133 kms−1Mpc−1; speed decreases with distance.
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.