1. 11/9/15
Ch. 15 Energy Day 1 Notes
There is going to be A LOT of info in a VERY SHORT amount of time. It’ll be good though. Everyone loves this chapter.

2. Objectives
SWBAT explain the relationship between work and energy
SWBAT explain the “Law of Conservation” of Energy in their own words.
SWBAT describe the 6 forms of energy covered in class

3. We need a little background first…
Work – when a FORCE is applied to an object AND the object moves a DISTANCE.
Work = Force x Distance
Measured in Joules (J)
How much work did the weight lifter do?
150 N x 2 m = 300 J of work
150 N
2 m
Force
Distance

4. Bill Bob Energy Who has more Energy? Bill or Bob?
Definition
Energy is the ability to do work.
Measured in Joules (J).
Who can do more work?
Bill
Bob

5. Energy Energy Energy Energy
The Big Idea…
Energy is a bank account. Your money never goes away, it just changes form. You do work on your bank account by spending your money, and turning it into the things you buy. Like pizza, or Black Ops 3. Your money is now Black Ops 3. If you wanted, you could turn it back into money if you wanted.
Energy
Energy
Energy
Energy
WORK
WORK
WORK

6. The Law of Conservation of Energy
Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes

7. The 6 Forms of Energy
Mechanical Energy Associated with motion and position of an object. (Kinetic (KE) + Potential (PE) Energy)
Thermal Energy
Associated with the temperature of an object
(How hot something is…)

8. The 6 Forms of Energy Continued
Chemical Energy Associated with the energy stored in chemical bonds. (Ex. The chemical energy in food, gives you energy to take these notes…)
Electrical Energy
Associated with energy of electric charges
(Ex. Plugging into an outlet)

9. The 6 Forms of Energy Continued
Electromagnetic Energy A form of energy that travels in waves. (Ex. Visible light, X-Rays, radio waves, etc.)
Nuclear Energy
Energy stored in atomic nuclei
(Ex. Nuclear power plants and atomic bombs)

10. Classification of Energy
Electromagnetic Energy
(light energy)
All Energy
Potential Energy (PE)
(stored energy)
Kinetic Energy (KE) (moving energy)
Elastic Potential Energy (energy stored in something elastic or rubbery. i.e. Springs, bouncy ball)
Gravitational Potential Energy
(energy stored by an object’s ability to fall somewhere)

11. 11/10/15
Ch. 15 Energy Day 2 Notes

12. Objectives
SWBAT calculate the gravitational potential energy of an object
SWBAT calculate the kinetic energy of an object

13. Gravitational Potential Energy (GPE)
Energy that is stored by an object’s height above a REFERENCE POINT.
Reference point – a place where the height of an object is measured from.
GPE = mass x gravity x height
GPE = m x g x h
What about Point 2?
(kg)
(9.8 m/s2)
(m) 2
1.5 m
A kitty has a mass of 2 kg.
What is the kitty’s GPE from Reference Point 1? 1

14. Kinetic Energy (KE) KE = ½ x mass x velocity2 KE = ½ x m x V2
The energy contained in an object that is moving.
KE = ½ x mass x velocity2
KE = ½ x m x V2
KE = 0.5 x ( kg) x (564 m/s) 2
= 1,447.3 J
An NFL linebacker can only hit with 960 J of energy.
(kg)
(m/s)
Bullet mass = 9.1 grams
.357 Magnum Bullet velocity = 564 m/s

15. 11/12/15
Ch. 15 Energy Day 3 Notes

16. Objectives
SWBAT calculate the mechanical energy of an object
SWBAT account for gains/losses in potential and kinetic energy of an object/system

17. Mechanical Energy (KE + PE)
Mechanical energy of an object is the sum of its kinetic energy and its potential energy.
It DOES NOT have to be a machine to have mechanical energy.
Problem: Brett Favre throws a 1 kg football at a speed of 5 m/s. It is a long, “Hail Mary” pass, that flies 7 meters above the ground. What is the football’s mechanical energy?

18. Conservation of Energy with PE and KE
The TOTAL ENERGY in a system is ALWAYS conserved.
Example: A Roller coaster is has ALL PE at the top of the hill, and it is converted into all KE at the bottom.
Example: A pendulum swinging constantly converts from PE to KE to PE…