Question

What is the escape speed from the surface of a planet whose radius is 5000 km, if the gravitational acceleration on its surface is 4.0 m/s21?

Answer 1

1/2*m v 2= GMm/R
g = GM/R2
GM/R = gR
V2 =2*g*R
V root 2gR = root (2*4*5000)=root 40000=200m/s