The height of the point vertically above the earth's surface, at which acceleration due to gravtiy becomes 1% of its value at the surface is (Radius of the earth =R)

Options

A. 3R
B. 9R
C. 18R
D. 6R

Answer

B

Explanation

`(g')/(g)=(1)/(100)=10^(-2)=[1+(h)/(R )]^(-2)`
`therefore 10 = 1+(h)/(R ) " " therefore h = 9R`