Question

A body weighs $63 \,N$ on the surface of the earth. What is the gravitational force (in newton) on it due to the earth at a height equal to half the radius of the earth?

Answer 1

Here, $m g=63 \,N , $
$h=R / 2$
As $\frac{g_{h}}{g}=\left(\frac{R}{R+h}\right)^{2}=\left(\frac{R}{R+\frac{R}{2}}\right)^{2}$
$=\left(\frac{2}{3}\right)^{2}=\frac{4}{9}$
$g_{h}=\frac{4}{9} g$
$\therefore m g_{h}=\frac{4}{9}\, m g$
$=\frac{4}{9} \times 63=28\, N$