Astronomers measure the radius of a star during two stages.
| Stage | Radius at start in km | Radius at end in km |
|---|---|---|
| P | 700 000 | 700 000 |
| Q | 700 000 | 840 000 |
During stage R, the inward effect of gravitational attraction becomes greater than the outward effect of fusion.
Which statement correctly explains the measurements and predicts what will happen during stage R?
During stage P the effects were balanced; during stage Q the inward effect was greater; during stage R the radius will increase.
During stage P the inward effect was greater; during stage Q the effects were balanced; during stage R the radius will decrease.
During stage P the effects were balanced; during stage Q the outward effect of fusion was greater; during stage R the radius will decrease.
During stage P the outward effect of fusion was greater; during stage Q the inward effect was greater; during stage R the radius will stay the same.
84 exam-style questions on AQA GCSE Physics 8.1 Solar system; stability of orbital motions; satellites, covering 8.1.1 Our solar system, 8.1.2 The life cycle of a star, and 8.1.3 Orbital motion, natural and artificial satellites. Each one has a worked solution and a mark scheme showing where the marks go.