320 Km above the surface of earth the value of acceleartion due to gravity is nearly 90% of ts value on the sruface fo the earth its value will be 95 % of the value on the eath surface

Options

A. nearly 160 km below the earth surface
B. nearly 80 km below the earth 's surface
C. nearly 640 km below the eath 's surface
D. nearly 320 km below the earth 's surface

Answer

D

Explanation

AT height `(g')/(g)=1-(2h)/(R )=90/100`
or `(2h)/(R )=1-90/100=10/100=1/10`
`rarrR=20h=20xx320=6400 km`
`rarr (d)/(R )=1 -95/100=5/100=1/20`
`rarr d=(R )/(20)=6400/20=320 km`