A body weighs `64 N` on the surface of Earth. What is the gravitational force on it due to the earth, at a height equal to half the radius of Earth ? Acceleration due to gravity on the surface of Earth is `10 m s^(-2)`.

Explanation

Weight of body `= mg = 63 N`
At height `h`, the value of g' is given by, `g' = (gR^(2))/((R + h)^(2)) = (gR^(2))/((R + R//2)^(2)) = (4)/(9) g`
Gravitational force on body at height `h` is `F = mg' = m xx (4)/(9) g = (4)/(9) xx 63 = 28 N`