1. An opposing force that effects us everyday
Friction
An opposing force that effects us everyday

2. First, remember what a force is!!
Force: push or a pull on an object
3 Characteristics
1. Have size
2. Have direction
3. Have units

3. There is NO SUCH THING as a completely smooth surface!!
What is Friction Then?
Friction: a force that opposes motion between two surfaces that are touching
There is NO SUCH THING as a completely smooth surface!!

4. There are microscopic hills and valleys on the surface of every object
The Source of Friction
The surface of any object
Hills and Valleys
There are microscopic hills and valleys on the surface of every object
As the surfaces move back and forth, the hills and valleys stick to one another

5. What Controls The Amount of Friction?
2 Major Factors
1. Roughness of surfaces
Rougher the surface = more friction
2. Force pushing the objects together
Greater the force = more friction

6. Large amount of opposing force
2 Types of Friction
Sliding Friction
Requires a great amount of force to move the object
Large amount of opposing force

7. Small amount of opposing force
2 Types of Friction
Rolling Friction
Requires much less force to move the object
Small amount of opposing force

8. How Can We Increase and Decrease Friction?
Lubricants: substances that are applied to surfaces to reduce friction between them
Such things as Oils, Waxes, and Greases

9. How Can We Increase and Decrease Friction?
Increase Friction
1. Increase the force acting on the object
2. Increase the
roughness of the
surface
Paperweights, Sand on roads, sanding surfaces