A pendulum swing is a concrete example of how energy is conserved in a system. The conversion and conservation of energy is as follows:
1. Gravitational potential energy is possessed by the system when you lift a bob on one side of the pendulum (highest point of swing).
2. When you release the pendulum bob, the GPE is converted to kinetic energy to allow the system to fall to its lowest point (vertical to the ground)
3. When it reaches its lowest point, the bob attains its maximum kinetic energy and minimum GPE.
4. The maximum kinetic energy obtained by the system allows the bob on the other side of the pendulum to swing up, converting the kinetic energy back to GPE.