Physics - Gravitation Question with Solution | TestHub

Weight on the surface of the earth is $W=mg=45$ N.

The acceleration due to gravity at a height $h$ is given by $g_h=g{\left(\frac{R}{R+h}\right)}^2$.

Given $h=\frac{R}{2}$, we have:

$g_h=g{\left(\frac{R}{R+\frac{R}{2}}\right)}^2=g{\left(\frac{2}{3}\right)}^2=\frac{4}{9}g$

The gravitational force on the body at this height is:

$W_h=m{g}_h=\frac{4}{9}mg=\frac{4}{9}\times 45=20$ N.

Answer: 20 N