Q.

A body of mass m is taken from Earth’s surface to the height h equal to twice the radius of Earth (Re), the increase in potential energy will be: (g = acceleration due to gravity on the surface of Earth)            [2023]

1 12mgRe  
2 3mgRe  
3 23mgRe  
4 13mgRe  

Ans.

(3)

U=-GMemr and Ui=-GMemRe

Uf=-GMem(Re+h)=-GMemRe+2Re=-GMem3Re

Increase in internal energy ΔU=Uf-Ui

       =23GMemRe

=23GMeRe2mRe=23mgRe