Question

A body weights 72N on the surface of the earth.what is the gravitational force on it due the earth at the height equal to half the radius of earth​

Answer 1

Let  W is the weight of body on the surface of earth, h is the height of body from the surface of earth, r is the radius of earth and Fg be the gravitational force.

Then, From Newton's Gravitational Law:

Fg = W / (1 + h/r)²

here,

W_earth = mg = 72 N

h = r / 2

Now,

Fg = 72 / (1+(r/2)/r)

    = 72 / (1 + 1/2)²

    = 72 * 4/9

Fg = 32 N