Nuclear fusion
2 marks · NormalDescribe how nuclear fusion in a star results in a stable output of energy over millions of years.
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Fusion reactions in a star convert hydrogen into helium, releasing energy that balances the force of gravity. This balance maintains temperature and pressure, leading to a stable energy output for millions of years.
Common mistakes: ignoring balance with gravity
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Marking points
B1 · 1 mark · States that fusion converts hydrogen into helium and releases energy.
B2 · 1 mark · Explains energy release balances gravity, creates steady output.
Worked solution
Nuclear fusion in a star continuously converts hydrogen into helium, releasing energy. This energy pushes outward and balances the inward pull of gravity, allowing the star to remain stable and release a constant output of energy for millions of years.