Mechanical energy moves objects from place to place. An example is the wind as it turns a windmill. Water flowing down a stream is another example of mechanical energy.
There are two types of mechanical energy – kinetic energy and potential energy.
Kinetic energy is energy in motion like moving water and wind.
Potential energy is stored energy. Some examples are the petrol sitting in the tank of a car or the water in a lake in the mountains. This energy is referred to as potential energy because, if it were released, it would do a lot of work.
A roller coaster uses both kinetic and potential energy. When it is on its way up, it is using kinetic energy since the energy is in motion. When it reaches the top it has potential (or stored) energy. When it goes down the hill, it is using kinetic energy again.
Radiant energy is energy that is pushed into motion by using heat. An example is a fire in your fireplace. Radiant energy can move through space. Heat (from a barbecue) and light (from a light bulb) are forms of radiant energy. The sun and the stars are more examples of radiant energy which moves through space.
Electrical energy is when electricity creates motion, light or heat and comes from the movement of electrons within an atom. An example of electrical energy is the energy produced by the electric coils on a stove. It can be created at a power station or inside a battery, and can power everything from computers to refrigerators. Lightning and static electricity are also forms of electrical energy.
Chemical energy is energy that is released by a chemical reaction. The food you eat contains chemical energy that is released when you digest your meal. Wood, coal, petrol and natural gas are fuels that contain chemical energy. When these fuels are burned, the chemical energy changes to radiant energy, as heat and light.