The radius of earth is about `6400Km` and that of mars is about `3200 km` The mass of the earth is about `10`times the mass of mars. An object weight `200N` on earth 's surface, then its weight on the surface of mars will be:

Options

A. `6N`
B. `20N`
C. `40N`
D. `80N`

Answer

D

Explanation

`g_(E)=(GM)/(R^(2))`
`gM=(GM')/(R^(12))=(GM//10)/((R^(2))//4)=2/5(GM)/(R^(2))=2/5g_(E)`
`W_(M)=W_(E)=2/5=200xx2/5=80N`