1. Forces
FORCEMAN

2. What causes things to move?
What is a force?
A push or a pull that one body exerts on another.

3. Balanced

4. Question: Can there be balanced forces on a object and the object still have motion?

5. The Body will Accelerate
Unbalanced
If the forces acting on a body are "unbalanced" this means that there is a "net" or "resultant" force.
The object will do one of the following:
Speed Up
Slow Down
Change the Direction of its Motion
In other words….
The Body will Accelerate

7. What will happen? Abruptly stopping a cart with a suitcase on top….
You set your coffee cup on the dash and then make a sharp left turn…..
You throw a tennis ball in outer space.

8. Forces that oppose motion

9. Friction

10. Forces that oppose motion
-Friction is a force that opposes motion between two surfaces that are touching each other.
Friction Song 1
Friction Song 2
Acts in the opposite direction of the motion

11. -Air resistance is the force air exerts on a moving object
Forces that oppose motion
-Air resistance is the force air exerts on a moving object

12. Friction What Causes Friction?
Microscopic, electrostatic interactions between contacting surfaces
Friction

13. Types of Friction
Static Friction
Sliding Friction
Rolling Friction

14. Types of Friction
1. Static friction is the force between two surfaces in contact that keeps them from sliding when a force is applied.

15. Static friction- occurs between the surfaces of 2 objects that touch but do not move against each other. Static friction must be overcome for one of the objects to move.

16. Static Friction (FS)

17. Not enough static friction

18. 2. Sliding – force required to keep an object sliding at a constant speed
3. Rolling – force required to keep an object rolling at a constant speed
To decrease friction, surfaces can be lubricated with a liquid such as oil.

20. Friction Song