The inward gravitational forces and outward radiation pressure forces in a stable main-sequence star remain balanced for its entire stable lifetime.
For a specific star with a mass similar to the Sun, this stable lifetime is estimated to be 12 billion years.
This star has currently been in this balanced state for 35% of its total stable lifetime.
Calculate for how many billions of years these forces have been balanced in this star.
Practise Edexcel GCSE Physics Stellar evolution and observing the Universe with exam-style questions for Foundation and Higher tier. 53 questions, matched to the Edexcel GCSE Physics (1PH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.