1. Energy and Energy Resources Pages 240 to 247
Chapter 9
Energy and Energy Resources
Pages 240 to 247

2. Terms to Learn Energy: the ability to do work.
Kinetic Energy: the energy of motion(KE)
depends on speed and mass
Potential Energy: the energy of position or shape.(PE)

3. ENERGY
Energy is the ability to do work; work is the transfer of energy.
Both energy and work are expressed in Joules (J).

4. ENERGY
The tennis player is doing work on her racket because she has energy
When she does work on the racket, the racket gains the ability to do work on the ball.

5. Energy is transferred from the tennis player to the racket.
When the racket does work on the ball, the ball gains the ability to do work on something else. Energy is transferred from the racket to the ball.

6. Kinetic Energy (K.E.) TYPES OF ENERGY Depends on: Speed and Mass
Speed has more of an effect on Kinetic Energy than mass because speed is squared in the equation.

7. Kinetic Energy Kinetic energy=mv2 2 m=mass (kg) v=velocity (m/s)
KE=Joules
As the roller coaster descends its velocity increases causing the roller coaster to gain kinetic energy.

8. Forms of Energy Thermal energy Chemical energy Electrical energy
Sound energy
Light energy
Nuclear energy

9. 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.
See Figure 5 on p. 244

10. 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.

11. Electrical Energy Is the energy of moving electrons
Both kinetic and potential energy

12. Sound Energy Is caused by an object’s vibrations
It is a form of potential and kinetic energy

13. Light Energy
Is produced by the vibrations of electrically charged particles
Kinetic energy

14. Nuclear Energy
The energy associated with changes in the nucleus of an atom Nuclear power plants use uranium, a radioactive element, to create electricity.
Potential Energy

15. POTENTIAL ENERGY Also known as P.E. or G.P.E.
Energy of position or shape
Gravitational potential energy depends on:
Weight and
Height (distance above Earth’s surface)

16. POTENTIAL ENERGY
The stored potential energy of the bow and string allows them to do work on the arrow when the string is released

17. PE = mass ● g ● height GPE = weight ● height Weight = mass ● g
POTENTIAL ENERGY
PE = mass ● g ● height or
GPE = weight ● height
Weight = mass ● g

18. GPE is measured in Joules (J) mass is measured in kg
Potential Energy
GPE is measured in Joules (J)
mass is measured in kg
height is measured in meters (m)
g is acceleration due to gravity and is a constant number- 9.8 m/s2

19. Energy Partners

20. 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

21. Mechanical Energy
When potential energy increases (or decreases), kinetic energy has to decrease (or increase) in order for mechanical energy to remain constant.

22. Chapter 9 Energy Is Conserved Within a Closed System
Conservation of Energy
Energy Is Conserved Within a Closed System
A closed system is a group of objects that transfer energy only to each other.
The Law of Conservation of Energy states that energy cannot be created or destroyed.
Energy can be converted from one form to another. But all of the different forms of energy in a system always add up to the same total amount of energy.

23. No Conversion Without Thermal Energy
During energy conversions some of the original energy is always converted into thermal energy
This is due to friction
This energy is not always useful