Question

The change in potential energy, when a body of mass m is raised to a height nR from the earth's surface is (R = Radius of earth)

• A. $m g R \frac { n } { n - 1 }$
• B. nmgR
• C. $m g R \frac { n ^ { 2 } } { n ^ { 2 } + 1 }$
• D. $m g R \frac { n } { n + 1 }$

Answer 1

Answer: (D)

$m g R \frac { n } { n + 1 }$

Answer 2

$\Delta U = \frac { m g h } { 1 + \frac { h } { R } } = \frac { m g n R } { 1 + \frac { n R } { R } } = \frac { n m g R } { n + 1 }$