What is the work done by the force of gravity in the following cases ?$( a)$. Satellite moving around the earth in a circular orbit of radius 35000 km.$( b)$. A stone of mass 250 g is thrown up through a height of 2.5 m.

$( a)$. If an object is moving in a circular path, On a complete revolution the displacement is zero. Therefore, the work done is zero. So the satellite moving around the earth in a circular orbit, the work done is zero.

$( b)$. When a stone of mass 250 g is thrown up through a height of 2.5 m.

Here mass $m=250\ gm=250\times10^{-3}\ kg$

Height $h=2.5\ m$

Therefore, the work done for throwing up a stone $W=mgh$

$=250\times10^{-3}\times2.5\times9.8$           [$g=9.8\ m/s^2$]

$=6,125\times10^{-3}$

$=6.125\ Joule$

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Updated on: 10-Oct-2022

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