The radius of the earth is 4 times that of the moon and its mass is 80 times that of the moon. If the acceleration due to gravity on the surface of the earth is `10m//s^2` that on the surface of the moon will be .........

Options

A. ` 1ms^(-2)`
B. ` 2ms^(-2)`
C. ` 3ms^(-2)`
D. ` 4ms^(-2)`

Answer

B

Explanation

`implies` on earth `g_e = (GM_e)/(R_e^2) ` and
on moon `g_m =(GM_m)/(R_m^2)`
`:. g_m/(g_e)=(M_m)/(M_e)xx((R_e)/R_m)^2`
`=(1/8)(4)^2`
` :. (gm) /10 =1/5`
`:. g_m = 2ms ^(-2)`