What is energy? The ability to do work.
Energy (scalar) comes in several basic forms: Kinetic, Potential; these comprise Mechanical Energy, as well as Thermal, Electromagnetic, Chemical, Sound, etc.
1. Kinetic Energy (K) K=½mv2. The energy of an object due to its motion.
2. Potential Energy (U): The energy of an object due to its position or due
to its geometrical configuration.
Examples: Gravitational potential energy U=mgh.
Energy stored in a spring U=½kx2.
3. All other energy forms (O): Thermal,
Electromagnetic, Chemical, Sound, etc.
The MKS energy unit is the joule (J). 1 J =
1 N m = 1 kg m2/s2