1. What is Energy?

2. Qualitative Definition of Energy:
Energy is the currency of change.
Energy, though not a substance, is conserved like a substance and has the capability to cause change.
Energy is transferred from place to place, but is never destroyed.
Tracking the changes in a system will track the energy transferred.

3. Can energy be used up?
Your experience of energy probably makes it appear that energy is “consumed” or used up:
Bouncing ball is dropped and comes to a rest
Cell phone goes dead after it runs out of battery
Spring powered toy becomes unwound and comes to a stop.
However, energy has not been used up, it has been transferred elsewhere.
Total Energy is Conserved!

4. Energy is Like Money Energy can be stored in different accounts.
Just as all money is in units of currency ($, pesos, etc.) Energy has its own units (J,C, etc.) But they all mean energy
Monetary Account
Energy Account
Checking Account
Kinetic Motion
Saving Account
Elastic
Wallet
Gravitational
Xbox Credits
Cash

5. Energy is Transferred like Money:
Energy like money can be transferred in many ways:
Energy Transfer
Monetary Transfer
Radiating
Write a Check
Heating
Hand Cash
Credit Card
Working
iPay

6. Energy is like Information
Both energy and information can be stored and transferred in different ways:
Information Storage
Information Transfer
Books
Reading
Music
iTunes
Memory
Speaking
Pictures
Instagram

7. Elastic Energy Amount of elastic energy depends on:
How far the spring is deformed (stretched or deformed) in meters
How difficult it is to deform the spring
More length = more energy
More force to deform= more energy

8. Spring Launches Cart Remember energy is the currency of change.
Where does the energy come from and where does it go?
Energy stored in spring and is transferred into the motion of the cart (kinetic energy).

9. Kinetic Energy (K.E.)
Kinetic Energy is the energy associated with motion.
Amount of K.E. depend on
How fast (speed)
How massive the object is (mass)
Greater Speed = more KE
Greater Mass = more KE

10. Gravitational Energy
Gravitational Energy is the energy associated with the height of an object.
Scientists classify this as potential energy as well
Depends on:
Height, Mass, Gravitational Field Strength

11. Dissipated Energy
Energy that gets transferred into an unrecoverable account.
Heat, (thermal), friction, sound, etc.
Like banking fees or taxes

12. Energy Bar Graphs Energy Accounts: Elastic Energy Kinetic Energy
Gravitational Energy
Dissipated Energy

13. Example 1 The spring is part of our system “system= spring + cart”
You could have E diss too.
Spring
Cart
Earth