1. Energy
Chapter 7

2. Energy Is the ability to do work
A quantity that describes the ability of an object to change or cause change
Appears in many different forms
Measured in joules

3. Types of Energy Mechanical energy Thermal energy Electrical energy
Chemical energy
Nuclear and Radiant energy
Electromagnetic Spectrum
Gravity

4. Mechanical Energy
Mechanical energy is the energy possessed by an object due to its motion or its position.

5. FORMS OF ENERGY
Thermal energy – the total energy of the particles that make up an object.
The higher the temperature, the faster particles move and the more K.E. they have
Thermal energy also depends on the number of particles there are in a substance.

6. FORMS OF ENERGY
Chemical energy – the energy of a compound that changes as its atoms are rearranged to form new compounds. Chemical energy is a form of potential energy.
Electrical energy – the energy of moving electrons. Electrical energy can be either K.E. or G.P.E.

7. FORMS OF ENERGY
Sound energy – caused by an object’s vibrations. Sound energy can be a form of either K.E. or P.E.
Light energy – produced by the vibrations of electrically charged particles.
Nuclear energy – the energy associated with changes in the nucleus of an atom.

8. Kinetic Energy Kinetic energy=mv2 2 m=mass v=velocity
Measured in Joules
As the roller coaster descends its velocity increases causing the roller coaster to gain kinetic energy.

9. Potential Energy Potential Energy is stored energy.
Stored chemically in fuel, the nucleus of atom, and in foods.
Or stored because of the work done on it:
Stretching a rubber band.
Winding a watch.
Pulling back on a bow’s arrow.
Lifting a brick high in the air.

10. Gravitational Potential Energy
Potential energy that is dependent on height is called gravitational potential energy.

11. Gravitational Potential Energy
“The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass have greater G.P.E.
The formula to find G.P.E. is
G.P.E. = Weight X Height.

12. Potential Energy
Ep=mgh
m=mass
g=acceleration due to gravity
h=height

13. Terms to Learn
Mechanical Energy: is the total energy of motion and position of an object. It can be all potential energy, all kinetic energy, or some of both.
Mechanical energy=potential energy+kinetic energy
ME=PE+KE

14. 7.2 Energy flow How can we predict how energy will flow?
One thing we can always be sure of is that systems tend to move from higher to lower energy.

15. Ball speeds up
Ball slows down

16. The Law of Conservation of Energy
Energy can be neither created nor destroyed by ordinary means.
It can only be converted from one form to another.
If energy seems to disappear, then scientists look for it – leading to many important discoveries.