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)

I method ΔU=mgh1+hR=mg nR1+nRR=nm gRn+1 II method r1=R, r2=R+h and U=-GmMR ΔU=U2-U1=GmM1r1-1r2=GmM1R-1R+h =GmM1R-1R+nR=GmMR1-11+n =mgR2R1+n-11+n∵g=GMR2⇒GM=gR2 =nmgR(n+1)