A body of mass m is situated at a distance 4Re above the earth’s surface, where Re is the radius of earth. How much minimum energy be given to the body so that it may escape :
Answer & explanation
Correct answer: option 3
Potential energy of the body at a distance 4Re from the surface of earth :
\(U = - \frac{mgR_e}{1 + \frac{h}{R_e}}\)
\(U = - \frac{mgR_e}{1 + 4}\)
\(U = - \frac{mgR_e}{5}\) ... [As h = 4Re : given]
So minimum energy required to escape the body will be mgRe/5.