Question

what is the work done by gravity on a satellite moving around the earth. justify

Answer 1

Dear Student,

As we know that the work done is given by, W = Fs cos$\theta$ ("F" stands for force and "s" for displacement, $\theta$ is the angle between them)

Here, the Earth's gravity or gravitational force provides the centripetal force, which acts towards the centre of the Earth. This force moves the satellite into a circular path of some radius (R) around the Earth.

However, the motion of the satellite is along tangent of that circular path in which the satellite is moving, which makes the angle between centripetal force and displacement is 90 degrees.

That implies the work done (W) = Fs cos$\theta$ = Fs cos90$°$ = 0. Therefore, work done by gravity on a satellite moving around the earth is zero.