An astronaut of mass 80 kg lands on a planet,the radius of which is half that of the earth and the mass of which is three times that of earth.what will be the force of attraction which this planet has on him?

Answer 1

F = G M m /(r^2) = m g

= G M (3m)/(.25 r^2) = 12 G M m/r^2

so 12 m g = 12 * 80 * 9.81
= 9418 Newtons