Question

A passenger in a spaceship going round the earth in a circular orbit of radius 2Re has a mass of 60.0kg. Given that Re is the average radius of the earth, calculate the gravitational potential energy of the astronaut.

Answer 1

$$U=-G\frac{mM}{2R}\\U=-6.67\cdot10^{-11}\frac{(60)(5.96\cdot10^{24})}{2(6.37\cdot10^{6})}=-1.87\cdot10^9\ J$$