Question

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

Options

• 100 N

• 40 N

• 200 N

• 80 N

Answer 1

80 N

Explanation:

On Earth's surface `g=(GM_1)/R_1^2`

On Mars's surface `g=(GM_2)/R_2^2`

`thereforeg^'/g=M_2/M_1*R_1^2/R_2^2=1/10(2/1)^2`     `[because R_1/R_2=2]`

`thereforeg^'/g=4/10=0.4`

g' = 0.4g

∴ mg' = 0.4mg = 0.4 × 200 = 80 N