At what height from the surface of earth, the gravitation potential and the value of g are  -5.4×107Jkg-2 and  6ms-2, respectively? (Take,  the radius of earth is 6400 km) [NEET 2016]

Gravitational potential at some height h from the surface of the earth is given by                                V=-GMR+hand acceleration due to gravity at some height h from the surface of the earth can be given as                                   g=GM(R+h)2From Eqs. (i) and (ii), we get         |V|g=GM(R+h)×(R+h)2GM⇒|V|g=R+h∵  V=-5.4×107Jkg-2,g=6 ms-2and    R = 6400km  =6.4×106 mSubstituting these values in Eq. (iii), we get5.4×1076=6.4×106+h⇒h=(9-6.4)×106=2.6×106 m⇒h=2600 km