Gravitation 2 Question 5
8. If $g$ is the acceleration due to gravity on the earth’s surface, the gain in the potential energy of an object of mass $m$ raised from the surface of the earth to a height equal to the radius $R$ of the Earth, is
$(1983,1 \mathrm{M})$
(a) $\frac{1}{2} m g R$
(b) $2 m g R$
(c) $m g R$
(d) $\frac{1}{4} m g R$
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Answer:
Correct Answer: 8. (a)
Solution:
- $\Delta U=\frac{m g h}{1+h / R}$
Given, $h=R$
$$ \Delta U=\frac{m g R}{1+R / R}=\frac{1}{2} m g R $$
