Most of the energy under our control is in the form of potential energy.  Potential energy can be viewed as motion waiting to happen.  When the motion is needed, potential energy can be changed into one of the six forms of kinetic energy.

Kinetic energy is energy at work.  A lawn mower cutting grass, a car racing down a hill, and students running home from school are examples of kinetic energy.  So is the light energy emitted by lamps.  Even electrical energy is kinetic energy.  Whenever we use energy to do work, it is in the kinetic state.

Figure 3 Energy transfer in a pendulum PE=potential energy KE=kinetic energy Click on the green box to start.