Two general classifications of energy are potential
energy and kinetic energy.
Potential energy is stored energy.
It is the energy that an object possesses because of its position.
The classic example is a boulder sitting on a cliff above a river.
Because of the boulder's altitude,
it has stored energy capable of making a splash in the water if it were
rolled down. This stored energy is the boulder's potential energy.
Some substances like charcoal and propane have a lot of stored
energy within the relative positions and arrangements of atoms of the substances.
This stored energy is also potential energy, and it is referred as chemical
Kinetic energy is the energy of
When the boulder rolls down the
cliff, its potential energy is converted
to kinetic energy. How much kinetic energy the boulder possesses depends
on the mass and the velocity of the boulder.
When we light the charcoal or burn propane, the potential energy
of these substances are converted to heat energy
by giving off heat. Heat is a form of kinetic energy.