Gravitational potential energy
When work is done on an object it may also lead to energy being transformed to the object in the form of gravitational Potential energy, in this instance, is associated with gravitational potential energy - the energy gained while rising a certain height. Measured in joules (J) . For example, the cable car gained potential energy as it rose into the mountains. of the object.
Gravitational potential energy is the energy an object has by virtue of its position above the surface of the Earth. When an object is lifted, work is done. When work is done in raising the height of an object, energy is transformed as a gain in the gravitational potential energy of the object.
For example, suppose you lift a suitcase of mass \(m\) through a height \(h\). The weight \(W\) of the suit case is a downward force of size \(mg\). In lifting the suitcase, you would have to pull upwards on it with a force equal in size to its weight, \(mg\).
When this force (equal to the weight mg, but upwards) is applied to the suitcase over the distance h:
\(Work\,done=force\,\times\,distance\,upwards=mg\,\times\,h\)
This energy is transformed to potential energy when raising the object through a known height.
\(Energy = mass \times gravitational\,field\,strength \times height\)
\(E = m \times g \times h\)
This is the relationship used to calculate gravitational potential energy.
\({E_p} = mgh\)
where m is the mass of the object in kilograms (kg), g is the Force per unit mass. Measured in newtons per kilogram (N/kg)., (for positions near the surface of the Earth \(g\) = 9∙8 newtons per kilogram (\(N kg ^{-1}\) and h is the height above the surface of the Earth in metres (\(m\)).
