1. Energy: Forms and Changes
CHAPTER 15
Energy: Forms and Changes

2. Nature of Energy Energy is the ability to do work.
Measured in Joules
Objects gain energy when work is being done on them.
Objects use energy to do work.
There are 5 forms of energy:
1. Mechanical 2. Heat 3. Chemical 4. Electromagnetic 5. Nuclear

3. Mechanical Energy Energy of Motion
Examples: Sound, walking, rivers, oceans, riding a bike, a plane flying, etc….

4. Heat Energy All matter is made up of tiny particles called atoms.
Heat energy is the motion of atoms.
The faster the atoms move, the more heat that is produced.
Causes a temperature change or phase change

5. Heat Energy Phase Change: Solid Liquid Gas Example: Water
Ice Water Gas
Ice + heat = Liquid Water + heat = Gas
Gas – heat = Liquid Water – heat = Solid

6. Chemical Energy Stored in chemical bonds.
Energy is released when the bonds break.
Example: Water (H2O)
Breaking water into H & O will cause a release of chemical energy.

7. Electromagnetic Energy
Moving electrical charges
Examples: Power lines, electricity, light, lasers, X-rays, radio waves.

8. Nuclear Energy Stored in the nucleus of atoms
Released when atoms are split or when nuclei (more than one nucleus) fuse together.
The most concentrated form of energy. (meaning there is a lot of energy in a small amount of space)

9. Potential Energy How much energy there could be.
* Also called the energy of position
Objects with potential energy are not doing work. They are storing energy in order to do work.
Ex. A rubber band has potential energy. A stretched rubber band has even more potential energy!

10. Gravitational Potential Energy
Is potential energy that is dependent upon height.
G.P.E. = Weight x Height
Ex. Standing on a 1-m high diving board gives you GPE, but standing on a 3-m high diving board gives you 3 times the amount of GPE.

11. Kinetic Energy
The energy of motion
The faster and object moves, the more kinetic energy is has.
Kinetic energy depends upon the mass and velocity of the object.
K.E. = mass x velocity2 2