Question

A body of mass is taken from earth surface to the height $h$ equal to twice the radius of earth $\left(R_e\right)$ the inerease in potential energy will be:( $g$ = acceleration due to gravity on the surface of Earth)

• A. $\frac{1}{2} m g R_e$
• B. $3 m g R_e$
• C. $\frac{2}{3} m g R_e$
• D. $\frac{1}{3} m g R_e$

Answer 1

Answer: (C)

$\frac{2}{3} m g R_e$

Answer 2

The correct answer is (C) : $\frac{2}{3} m g R_e$
U=r−GMe​m​
Ui​=Re​−GMe​m​
Uf​=(Re​+h)−GMe​m​=Re​+2Re​−GMe​m​
3Re​−GMe​m​
Increase in internal energy ΔU=Uf​−Ui​
=32​Re​GMe​m​
32​Re2​GMe​​mRe​
=32​mgRe​