A computer model is run twice to investigate the main-sequence stage of a massive star. The model gives these results:
| Model run | Usable hydrogen at the start | Main-sequence duration |
|---|---|---|
| Standard run | 3.0 × 1030 kg | 6.0×106 years6.0 \times 10^{6}\ \text{years}6.0×106 years |
| High-fuel run | 6.0 × 1030 kg | 6.0×106 years6.0 \times 10^{6}\ \text{years}6.0×106 years |
The model gives the same main-sequence duration in both runs.
Which statement explains this result?
The average mass of hydrogen fused each year is four times as great in the high-fuel run.
The average mass of hydrogen fused each year is twice as great in the high-fuel run.
The average mass of hydrogen fused each year is half as great in the high-fuel run.
The average mass of hydrogen fused each year is the same in both model runs.
75 exam-style questions on Edexcel GCSE Physics 7.3 Stars, covering 7.3.1 Evolution of stars similar to the Sun, 7.3.2 Evolution of massive stars, and 7.3.3 Observing the Universe. Each one has a worked solution and a mark scheme showing where the marks go.