Which statement correctly describes the balance of forces in a stable, main-sequence star?
The outward force of gravity is balanced by the inward gas and radiation pressure.
The inward force of gravity is balanced by the outward pressure resulting from high temperatures and nuclear fusion.
The star expands continuously because the outward pressure exceeds the inward gravitational force.
The star contracts continuously because the inward gravitational force is much greater than the outward pressure.
25 exam-style questions on CIE IGCSE Physics 6.2.2a Galaxies and astronomical distances. Each one has a worked solution and a mark scheme showing where the marks go.