A body of mass m is situated at a distance equal to 2R ( R- radius of earth) from earth's surfac

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7.Gravitation

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A body of mass $m$ is situated at a distance equal to $2R$ ($R-$ radius of earth) from earth's surface. The minimum energy required to be given to the body so that it may escape out of earth's gravitational field will be

A

$mgR$

B

$\frac{mgR}{3}$

C

$\frac{mgR}{2}$

D

$\frac{mgR}{4}$

Solution

$\mathrm{E}_{\mathrm{es}}=-\mathrm{PE}$

$\Rightarrow \mathrm{PE}=-\frac{\mathrm{GMm}}{3 \mathrm{R}}$

$\Rightarrow \mathrm{PE}=-\frac{\mathrm{mgR}}{3} \Rightarrow \quad \mathrm{Ees}=\frac{\mathrm{mgR}}{3}$

Standard 11

Physics

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