2. What is Energy?
Energy is defined as the ability to cause changes in motion or position of things nearby.
Energy is described by what it can do rather than what it is. The actual changes made possible by energy are generally called work.
Take lightning, for example: the electricity that causes it is completely invisible. But the explosion of sound and light, the static it generates on radios and the damage it does to trees and buildings are all easy to see and hear. 

3. Kinetic Energy Energy of motion is kinetic energy.
Anything in motion has kinetic energy. Any motion will do — going somewhere, rotating (turning), or vibrating back and forth.

4. Potential Energy
Potential energy is energy that has been stored in some way. Potential energy is stored by overcoming some kind of force. Potential energy can be stored against gravity, a spring, or even stored in chemical bonds of molecules. 

5. Kinds of Potential Energy
Chemical potential energy: This is energy that is stored in chemical compounds in the bonds that hold them together.
Potential chemical energy can be released as:
Kinds of Potential Energy
Electricity
Batteries.
Light
A chemical light stick.
Heat A candle flame. 
Mechanical force A muscle contracting.

6. Kinds of Potential Energy
 Elastic potential energy: This is energy that is stored when springy materials are compressed, bent, or stretched. When these materials return to their normal shape, they usually do it very suddenly, releasing large amounts of mechanical energy.
 Gravitational potential energy: This is energy that is stored when an object is moved and held against the force of gravity. Anything that can be caused to fall has this form of potential energy.
 Nuclear potential energy: This is energy stored inside atoms, the smallest particles of an element. When the structure of an atom is rearranged, the result can be huge amounts of energy released.

7. What kind of energy is shown in this picture of a bungee jumper?

8. What goes up may come down!
A common example of this involves lifting. You do work against gravity while lifting something. The thing you lifted now contains gravitational potential energy. The amount of energy it has depends upon how heavy it is and how far it has been lifted.

9. Stretching Credibility
  Matter is made of atoms, and atoms combine to form molecules. Atoms and molecules are held together by springy bonds.
The strength of these bonds is partly what gives substances physical properties such as hardness, elasticity, its melting point, and others.
Substances such as rubber or spring steel can be stretched or deformed by applying some kind of force to them. Because of the bonds between their molecules, they quickly spring back to their original shape.

10. Stretching Credibility
Any object than can be deformed (have its shaped changed) and then return to its original shape can store elastic potential energy.
Energy stored this way is called elastic potential energy. Elastic potential energy is used in many human-made machines to do useful work.
How many devices can you think of that store energy in the form of elastic potential energy?

11. How many devices can you think of that store energy in the form of elastic potential energy?
Springs
Pole Vaulter’s Pole
Rubber Bands

12. Chemical Bonds
The chemical bonds between the atoms in a molecule contain chemical potential energy.
Chemical reactions involve the breaking of these bonds and formation of other chemical bonds.
Some chemical bonds contain more energy than others. If the new chemical bonds contain less energy than the old ones, then the chemical reaction releases energy.
Breaking the chemical bonds usually involves adding some energy first (activation energy).

13. Electric Potential Energy
Storing electric energy involves rearranging electrons to separate the negative and positive charges within a substance.
When you walk on a wool carpet you pick up electrons from the carpet. Since you have gained electrons, you now have a negative charge (and the carpet has a positive charge because it has lost electrons to you).
Your body now has electric potential energy

14. Nuclear Potential Energy
The largest stored energy source of all, however, is nuclear potential energy. Nuclear energy is released during nuclear reactions. These reactions usually result in the formation of new elements. This is what happens in our Sun. 
Nuclear reactions caused by the heat of the Sun's core cause atoms of hydrogen to be mashed together to form the element helium. During the course of this reaction, a tiny amount of mass is lost. That mass is converted into energy, which we see as sunlight. Albert Einstein's famous equation (E=mc2) tells us how much energy is stored within any amount of mass. 

15. Nuclear Potential Energy
What happens on the Sun is an example of a fusion reaction (hydrogen is fused to form a new element, helium).
Other nuclear reactions involve the splitting of one atom into two or more others. This is called nuclear fission.
Fission is the splitting or breakdown of atoms. The by- products of fission are usually radioactive, which means they give off radiation.
Radioactive waste by-products represent a huge environmental problem because they are extremely dangerous to health and the environment. All nuclear reactors are fission reactors.

16. The Sun's Energy The Sun provides more energy per year than all of humanity uses. This energy is less concentrated than, say, fossil fuel energy but we can reduce the use of fossil fuels by accessing more solar energy.

17. Types of Kinetic Energy
Mechanical energy: An object has mechanical energy if it is moving or has had energy stored either by moving it against gravity, or by stretching or flexing it elastically. A cyclist going over a jump or a person on a trampoline have mechanical energy. They have kinetic energy because they are moving, and they have gravitational potential energy because they will both fall (and, hopefully, land safely).

18. What’s the difference between the energy used bungee jumping and skateboarding?
What type of energy is used in each?
How are they different?
Are they the same?

19. Types of Kinetic Energy
Thermal Energy: The kinetic energy between the particles of a substance is called Heat is produced when thermal energy is being used to move atoms and molecules from a hotter to a cooler location. 
Electrical energy is the energy of moving electrons (tiny charged particles found inside atoms). Electrical energy may be potential or kinetic, depending upon whether a current is flowing at the time referred to or not.

20. Types of Kinetic Energy
Electromagnetic Energy: Electromagnetic energy is created by changes in electric magnetic fields. The only difference between the different kinds of electromagnetic energy is the frequency of vibration of the photons. Light comes to us as a stream of particles called photons, which carry energy. Ultraviolet, infrared (radiant heat), and radio waves are other forms of electromagnetic energy.

21. Hydrogen Fuel Cells Hydrogen is a highly useful gas. Under the right conditions, it can be combined with oxygen to form water and electricity. This is done inside a fuel cell, which is essentially a kind of battery. The fuel cell works by bringing hydrogen gas together with oxygen from the atmosphere, which generates large amounts of electrical current. The only by-product is water. The electricity produced this way drives powerful motors that can be connected to the wheels of a vehicle. Hydrogen shows great promise as a future replacement for gasoline in pollution-free automobiles. Fortunately, hydrogen is one of the most common forms of matter on planet Earth. Trouble is, there is almost no pure hydrogen to be found anywhere, because it is chemically bonded to other substances, such as carbon and oxygen. The challenge is to find efficient ways to make, store, and deliver hydrogen so that people can use it. Today, hydrogen is made from natural gas, a process that produces carbon dioxide, a greenhouse gas. Until hydrogen can be made cheaply and in large quantities from water, hydrogen-powered vehicles will continue to be pollutants.

22. Forms of Energy: Are We Up to Potential?