Question

A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest

• A. at the instant just after the body is projected
• B. at the highest position of the body
• C. at the instant just before the body hits the earth
• D. it remains constant all through

Answer 1

The correct option is C at the instant just before the body hits the earth

Power, $P=\overrightarrow{F}.\overrightarrow{v}=Fvcos\theta$
Just before hitting the earth $\theta =0^{\circ }$.
Hence, the power exerted by the gravitational force is greatest at the instant just before the body hits the earth.