MATTER AND ENERGY

2.5 - Energy

2.5.1 - Potential Energy and Kinetic Energy

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 energy.

Kinetic energy is the energy of motion.

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.

Section 3.5
Energy ..p62

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