Types of Energy
There are two types of energy:
- Potential (or stored energy)
- Kinetic (or energy in motion)
Kinetic Energy is energy in motion. Moving water and wind are examples of kinetic energy. Electricity is kinetic energy because, even though you can't see it happen, electricity involves electrons moving in a conductor.
Potential Energy is stored (or latent). Energy can be stored in many ways. A gallon of gasoline or a barrel of oil contains stored energy that can be released when we burn it. A lake in the mountains contains "stored" energy because, if it were released, it would do a lot of "work" on objects caught in its path. When we talk about oil, coal, wood, or gas, we are talking about "stored" energy.
Energy can be changed from one type to another. An example is a car being driven up a hill, during which time it is demonstrating kinetic energy or energy in motion. When it sits on the top of the hill it has potential, or stored energy. If it is then allowed to roll back down the hill the potential energy changes again into kinetic energy. A law of physics says that energy can be neither created nor destroyed, but it can change back and forth between forms.
Mechanical Energy is the energy of motion that does the work, like the wind turning a windmill.
Heat Energy is caused by the motion of matter. As the particles of matter absorb energy from their surroundings, a thermometer will measure the energy taken in as a rise in temperature. You warm as your body and clothing absorb heat energy given off by burning wood in your fireplace.
Chemical Energy is the chemical
reaction causing changes. Food and fuel
both store chemical energy.
Electrical Energy is when motion, light or heat
is produced by an electrical current like the
electric coils on your stove.
Gravitational Energy is the energy an object has due to a change in its position. Water in a lake behind a dam has potential energy because it is higher than the stream on the other side of the dam. When gravity pushes the water through the gates at the bottom of the dam, energy is released. Once the water gets down the hill, it has lost much of its gravitational energy.