Question

Two bodies of masses $10$ kg and $100$ kg are separated by a distance of $2m(G=6.67\times {10}^{-11}N{m}^{2}k{g}^{-2})$. The gravitational potential at the mid point on the joining the two are

• A. $7.3\times {10}^{-7}J/kg$
• B. $7.3\times {10}^{-9}J/kg$
• C. $-7.3\times {10}^{-9}J/kg$
• D. $7.3\times {10}^{-6}J/kg$

Answer 1

Answer: (C)

$-7.3\times {10}^{-9}J/kg$

$V_g=\frac{G(M_1-M_2)}{r}=\frac{-6.67\times {10}^{-11}\times 10}{1}-\frac{6.67\times {10}^{-11}\times 100}{1}$
$=-6.67\times {10}^{-10}-6.67\times {10}^{-9}$
$=-6.67\times {10}^{-10}\times 11=-7.3\times {10}^{-9}J/kg$