A body has a weight 72 N. When it is taken to a height `h=R`= radius of earth, it would weight

Options

A. 72 N
B. 36 N
C. 18N
D. zero

Answer

C

Explanation

`g=(g)/(1+(h)/(R ))^(2)=(g)/(4)` (at h=R)
`therefore w=mg=(mg)/(4) rarr W =(W)/(4)`
`therefore w=(72)/(4)=18 N`