Question

The mass of the earth is $6.0 \times 10^{24} \,kg .$ The potential energy of a body of mass $50\, kg$ at a distance of $6.3 \times 10^{9} m$ from the centre of the earth is

• A. $-3.23 \times 10^{9} J$
• B. $-3.19 \times 10^{6} J$
• C. $-2.5 \times 10^{6} J$
• D. $-4.0 \times 10^{11} J$

Answer 1

Answer: (B)

Here, mass of the earth $(M)=6.0 \times 10^{24} kg$, Mass of the body $(m)=50 kg$ and distance $(r)=6.3 \times 10^{9} m$ Potential energy,
$U=-\frac{G M m}{r}$
$=-\frac{\left(6.7 \times 10^{-11}\right) \times\left(6.0 \times 10^{24}\right) \times 50}{6.3 \times 10^{9}}=-3.19 \times 10^{6} J$