Question

The 0.5kg sphere to the right is immersed in a gravitational field created by a planet with a mass of 2x10^20kg and a radius of 3x10^4m. What is the strength of the field at the surface of the planet?

Answer 1

The strength of the field is

$$g=\dfrac{GM}{R^2}=14.8\text{ m/s}^2.$$