Why does energy never disappear?

To understand why energy doesn't disappear but changes forms we must first talk about the 7 main forms of enery. The 7 main forms of energy  are radiant (light) energy, chemical energy, mechanical energy, nuclear energy, electrical energy, heat (thermal) energy, and sound energy.

All forms of energy fall under two categories. Those two categories are potential and kinetic. Potential energy is stored energy and kinetic energy is motion.

Chemical energy is a form potential energy. Chemical energy comes from the bonds of atoms and molecules. Some examples of chemical energy are coal and natural gas.

Another form of potential energy is nuclear energy. Nuclear energy is energy stored in the nucleus of an atom. An example of nuclear energy is Uranium.

Mechanical energy is stored energy. Some examples of mechanical energy include compressed springs and stretched rubber bands.


Radiant (light) energy is a form of Kinetic energy. Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves.

Heat (thermal) energy is another form of kinetic energy. This form of energy is the internal energy in a substance. Heat energy is the vibration and movement of atoms and molecules within a substance. Geothermal energy is an example of heat energy.

Sound energy is the movement of energy through substances in longitudinal waves.

The last of the 7 forms of energy mentioned in the previous pages is electrical energy. Electrical energy is also an example of energy in motion. It is the movement of electrons. Lightning and electricity are exampls of electrical energy.


The world around us is full of energy. Energy exists in many forms. A lightning bolt has electrical energy. A flashlight has chemical energy. A  moving bicycle has mechanical energy. We harness various forms of energy to power tools and machines from flashlights to submarines.

Energy readily changes from one form to another. The law of Conservation of Energy  states that "Energy cannot be created or destroyed."

In other words, the total amount of energy in the universe never changes, although it may change from one form to another. Energy never disappears, but it does change form.

When we eat our food has stored energy in it. If we take a bite of our food and chew we are using mechanical energy ,as the food moves down to our stomach and through our intestines the mechanical energy  is turned into chemical energy. If we play sports after we eat or do something that requires alot of physical activity that chemical energy  is turned into heat energy.

Energy has many forms and can be found almost everywhere.