A body projected vertically from the earth reaches a height equal to earth's radius before returning to the…
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
at the instant just before the body hits the earth
it remains constant all through
at the instant just after the body is projected
at the highest position of the body
Solution
We know
$P=\overrightarrow{\mathbf{F}} \cdot \overrightarrow{\mathbf{v}}=F y \cos \theta$
So just before hitting $\theta$ is zero and both $F$ and $v$ are maximum.
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