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

• A. $13.34\times {10}^{-10}J$
• B. $13.33\times {10}^{-10}J$
• C. $6.67\times {10}^{-9}J$
• D. $6.67\times {10}^{-10}J$

Answer 1

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

$W=\Delta PE=\left(\frac{-GMm}{\infty }\right)-\left(\frac{-GMm}{R}\right)=\frac{6.67\times {10}^{-}11\times 100\times 10\times {10}^{-3}}{1}=6.67\times {10}^{-10}J$