A body weighs 72 N on the surface of the earth. What is the gravitational force on it due to earth at a height equal to half the radius of the earth from the surface

Options

A. 36N
B. 32 N
C. 144 N
D. 50 N

Answer

B

Explanation

`F = mg = 72 N`
`g' = g ((R_(e))/(R_(e) + h))^(2) = g ((R_(e))/(R_(e) + R_(e)//2))^(2)`
`=g [(2R_(e))/(3R_(e))]^(2) = (4)/(9) g`
F' = mg' = mg' `xx (4)/() = 72 xx (4)/(9) = 32 N`