Question

If the acceleration due to gravity at the surface of the earth is g, the work done in slowly lifting a body of mass m from the earth's surface to a height R equal to the radius of the earth is
(a) 12mgR
(b) 2mgR
(c) mgR
(d) 14mgR.

Answer 1

Answer:

Explanation:

At earth surface, P.E. of system is –GmM/R At a distance R from the earth’s surface, P.E. of system is – GmM/2R? ? U = - GmM / 2R + GmM/R ; ?U = GmM /2RNow GM/R2 = g; ?GM / R = gR ? ?U = ½ mgR