The radius of earth is about 6400 km and that of mars is 3200 km. The mass of the earth is about 10 times mass of mars. An object weights 200 N the surface of earth its weight on the surface of mars will be ..........

Options

A. 8 N
B. 20 N
C. 40 N
D. 80 N

Answer

D

Explanation

`implies` Let Weight on earth is `W_e` and acceleration of gravity `g_e` and weight on mass is `W_m` and accelerationof gravity `g_m`
`:. (W_m)/(W_g)=(gm)/("ge")`
`= (GM_m//R_m^2)/(GM_e//R_e^2)`
`= (M_m)/M_e xx(R_e/(R_m))^2`
`=(1/10)xx((6400)/3200)^2`
`=1/10 xx 4`
`:. W_m = 4/10 xx W_g`
`:. W_m =4/10 xx 200`
`:. W_m = 80 N`