Question

A body weighs $700 \,gm$ wt on the surface of the earth. How much will it weigh on the surface of a planet whose mass is $\frac{1}{7}$ and radius is half that of the earth

• A. $200 $ gm wt
• B. $400$ gm wt
• C. $50$ gm wt
• D. $300$ gm wt

Answer 1

Answer: (B)

We know that $g = \frac{GM}{R^2}$
On the planet $g_P = \frac{GM/7}{R^2 / 4}$
$ = \frac{4g}{7} = \frac{4}{7}g$
Hence weight on the planet
$ = 700 \times \frac{4}{7} = 400$ gm wt