The radius of the earth is about `6400 km` and that of is about `3200 km`. The mass of the earth is about `10` times the mass of Mars. An object weighs `200 N` the surface of the earth. Its weight on the surface of mars would be

Options

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

Answer

A

Explanation

`g=(GM)/(r^(2))implies`
R is reduced to R/2 and the mass of the mars becomes 10 times
`g_("mars")=(4)/(10)g_("earth")` and `W_("mars")=(4)/(10)W_("earth")=80N`