Question

A body weighs $700gm-wt$ on the surface of the earth. How much will it weighs on the surface of a planet whose mass is $1/7$ and radius half of the earth

• A. $200gm-wt$
• B. $400gm-wt$
• C. $500gm-wt$
• D. $300gm-wt$

Answer 1

The correct option is B $400gm-wt$

$\begin{array}{c}g=\frac{GM}{R^2}\\ m^1=700g\\ M^1=\frac{M}{7}\&R^1=\frac{R}{2}\\ W^1=\frac{m^{1}G{M}^1}{{R^1}^2}\\ W^1=400gm-wt\end{array}$