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

The correct option is B

400 gm wt

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