Force fields and Newton's law of gravitationAQA A-Level Physics: Mind map

Exam questions on Force fields and Newton's law of gravitation

1. A torsion-balance experiment measures the gravitational attraction between a large lead sphere of mass 15 kg and a small lead sphere of mass 0.015 kg. The centres of the spheres are 0.060 m apart and the spheres are uncharged.
   Calculate the magnitude of the gravitational force on the small sphere. Use $G = 6.67 \times 10^{-11}\ \mathrm{N\,m^2\,kg^{-2}}$.2 marks
2. A student compares the gravitational field around a planet with the electric field around an isolated, positively charged metal sphere. Both bodies are treated as point sources.
   Explain what is meant by a force field, and why a small mass near the planet and a small charge near the sphere are both described as being in a force field.2 marks
3. The Earth has mass 5.97 × 10²⁴ kg and the Moon has mass 7.35 × 10²² kg. Their centres are 3.84 × 10⁸ m apart. Treat both bodies as point masses at their centres.
   Calculate the magnitude of the gravitational force of the Earth on the Moon. Use $G = 6.67 \times 10^{-11}\ \mathrm{N\,m^2\,kg^{-2}}$.3 marks