Astronomers observe three bodies orbiting the same distant star.
| Body | Type of orbit | Position in orbit | Distance from the star in m | Speed in km/s |
|---|---|---|---|---|
| L | circular | all positions | 6.0 × 1010 | 42 |
| M | circular | all positions | 2.4 × 1011 | 21 |
| N | highly elliptical | closest to the star | 3.0 × 1010 | 81 |
| N | highly elliptical | furthest from the star | 4.8 × 1011 | 5.1 |
A fourth planet is later detected in a stable circular orbit around the star. Its orbital speed is 30 km/s.
Explain how gravity accounts for the measurements in the table.
Your answer should include a prediction of where the orbit of the fourth planet is relative to the orbits of L and M.
80 exam-style questions on Edexcel GCSE Physics 7.1 The Solar System and gravity, covering 7.1.1 Weight and g on different bodies in space, 7.1.2 The Solar System, 7.1.3 Changing ideas about the Solar System, 7.1.4 Orbits of moons, planets, comets and satellites, and 7.1.5 Gravity and orbital motion. Each one has a worked solution and a mark scheme showing where the marks go.