Question

The gravitational potential due to earth at infinite distance from it is zero. Let the gravitational potential at a point $P$ be $-5J{kg}^{-1}$. Suppose, we arbitrarily assume the gravitational potential at infinity to be $+10J{kg}^{-1}$, then the gravitational potential at $P$ will be

• A. $-5J{kg}^{-1}$
• B. $+5J{kg}^{-1}$
• C. $-15J{kg}^{-1}$
• D. $+15J{kg}^{-1}$

Answer 1

Answer: (B)

$+5J{kg}^{-1}$

According to the problem as the potential at $\infty$ increases by $+10Jk{g}^{-1}$, hence potential will increases by the same amount everywhere (potential gradient will remain constant). Hence, potential point $P=10-5=+5Jk{g}^{-1}$