Gravitational Potential Energy
How do we describe freely falling bodies in terms of energy?
- Initially, if released from rest, there is NO kinetic energy.
- When the body falls, the kinetic energy increases.
- Where does this energy come from? What has changed? Only the position of the body with respect to the surface of the Earth!
Define the gravitational potential energy of mass m near the surface of the Earth as:
where h = height of mass above some reference point (e.g. floor)
As the mass falls, its potential energy is converted to kinetic energy. This energy can be recovered!
Works for complex problems - like roller coasters