Question

A body weighs $36kg$ on the surface of the Earth. How much would it weights on the surface of a planet,whose mass is $\frac{1}{9}$ and radius $\frac{1}{3}$ of that of earth?

Answer 1

$g=\frac{Gm}{r^2}$
$g=\frac{G\frac{m}{9}}{{\left(\frac{r}{3}\right)}^2}x\frac{Gm/9}{r^2}=\frac{Gm}{r^2}$
$\therefore$ same weight
$36kg$