Explain that a change in gravitational potential energy is related to work done.
 Potential Energy is energy that is "stored" which can be converted into other forms of energy.
 Gravitational potential energy (GPE) is the energy of a mass due to its position within a gravitational field.
 $e.g.$ If a ball is placed atop a cliff, it will have the stored energy.
 Keep in mind that GPE is equivalent to work done in moving something to a point.
 W = Fs:
 W is work done(J)
 F is force applied(N)
 s is displacement(m)
 W = Fs:
 From this equation, we can say that, if we take the Earth's surface as the point of 0 GPE, we can find GPE using:

 GPE = mgh
 m is the mass of the object(kg)
 g is the gravitational acceleration of Earth($9.8 ms^{2}$)
 h is the vertical distance between the object and the Earth's surface(m)
 Note that this equation can work with other planets as well, obviously switching the value of $9.8 ms^{2}$ to whatever the other planet's gravitational acceleration is.
 GPE = mgh

Richard Lou
page revision: 1, last edited: 29 Dec 2010 07:36