Question

treating the earth as a perfect sphere, show that the field strength at the earth's surface is around 9.8NkG*-1

Answer 1

F = M g gravitational force on M

M g = G M m / R^2

g = G m / R^2 where R is radius of earth and m the mass

g = 6.67E-11 N-m^2/ kg^2 * 5.98E24 kg / (6.37E6 m)^2

g = 6.67 * 5.98 / (6.37)^2 * 10 = 9.83 m/s^2