1. Energy and force
Unit 4: Motion & Forces

2. Energy vs. Work
Energy is transferred by a force moving an object through a distance.
Work is a transfer of energy.
So, work is the movement of energy.

3. 2 Major Forms of Energy 1. Kinetic Energy energy of motion
2. Potential Energy energy stored

4. Kinetic Energy KE= ½mv2 Equation: Units: KE= Joules (J)
M=mass in Kilograms (kg)
V= speed in meters per second (m/s)

5. Kinetic Energy Practice
A pitcher throws a kg baseball at a velocity of 30.0 m/s. How much kinetic energy does the ball have?

6. Potential Energy PE=mgh Equation: Units: PE=Joules (J)
M=mass in kilograms (kg)
G=9.8 m/s2 **Always 9.8
H=height in meters (m)

7. Potential Energy Practice
A 60.0-kg person walks from the ground to the roof of a meter tall building. How much potential energy does she have at the top of the building?

8. Forms of Energy Web & Examples

9. Law of Conservation of Energy
Energy is not created or destroyed only transferred.
Example: Spinning Top

10. What is force? Force=a push or a pull
Force is also a vector because it has magnitude (how much force) and direction.

11. Force Unit The unit for force is the Newton (N).
You exert about one Newton when you lift an apple (as reference).

12. Net Force If more than one force is acting, add the forces together.
If the forces are in opposite directions, add the forces together.
**Always adding forces

13. Balanced or Unbalanced?
If the forces do not cancel out, the force is considered unbalanced.
If unbalanced, the object can change speed or direction.
If the forces do cancel out, the force is considered balanced.
If balanced, the object does not change speed (or go anywhere).

14. Force Drawing Practice