The gravitational potential energy U r is always negative because when two masses come together slowly from infinity, work is done by the system. The unit of gravitational potential energy U r is Joule and it is a scalar quantity. The gravitational potential energy depends upon the two masses and the distance between them. .
. Gravitational potential energy near the surface of the Earth It is already discussed in chapter that when an object of mass m is raised to a height h, the potential energy stored in the object is mgh (Figure . ). This can be derived using the general expression for gravitational potential energy.
Figure . Mass placed at a distance r from the center of the Earth R e h o h << R e Consider the Earth and mass system, with r , the distance between the mass m and the Earth’s centre. Then the gravitational potential energy, - - - - Unit Gravitation The gravitational potential at a distance r due to a mass is defined as the amount of work required to take unit mass from the distance r to infinity and it is denoted as V(r). In other words, the gravitational potential at distance r is equivalent to gravitational potential energy per unit mass at the same distance r.
It is a scalar quantity and its unit is J kg - We can determine gravitational potential from gravitational potential energy. Consider two masses m and m separated by a distance r which has gravitational