ICSE Class 10 Answered
The term ' m g h ' is gravitational potential energy of mass m at a height h above earth surface or above some reference level.
Gravitational potential energy U(r) of a mass m is
where G is universal gravitational constant , M is mass of earth and r is distance of mass m from center of earth.
Gravitational potential energy U(R) of a mass m on earth surface is
............................ (1)
Gravitational potential energy U(R+h) of a mass m at a height h above earth surface is
If we take earth's surface as reference , then potential energy of mass m at a height h above earth surface is
By neglecting (h/R)2 and higher powers , we get
where ( G M )/R2 is acceleration due to gravity g on earth surface .
hence potential energy of mass m at a height h above earth surface = m g h .