Question

A particle of mass $10g$ is kept on the surface of a uniform sphere of mass $100kg$ and radius $10cm$. Find the work to be done against the gravitational force between them to take the particle far away from the sphere ( you may take $G=6.67\times {10}^{-11}{Nm}^2/{kg}^2$ )

• A. $3.33\times {10}^{-10}J$
• B. $13.34\times {10}^{-10}J$
• C. $6.67\times {10}^{-10}J$
• D. $6.67\times {10}^{-9}J$

Answer 1

The correct option is C $6.67\times {10}^{-10}J$

$W=\frac{GMm}{R}$

$W=\frac{6.67\times {10}^{-11}\times 100}{0.1}\times \frac{10}{1000}$

$=6.67\times {10}^{-10}J$