The kinetic energy needed to project a body of mass

• Gravitation

The kinetic energy needed to project a body of mass m from the earth surface (radius R) to infinity is

1. mgR
2. 2mgR
3. mgR/4
4. mgR/2

Answer

The kinetic energy needed to project a body from earth's surface to infinity is known as its escape energy.

KE = (GM_em)/R which is equal to mgR since gR=(Gm_e)/R

The correct option is A.