1. Chapter 5 Matter In Motion
Section 3 – Friction: A Force That Opposes Motion p

2. IMPORTANT DEFINITION
Friction – a force that opposes motion between two surfaces that are touching

3. The amount of friction between two surfaces depends on:
1. the roughness of the two surfaces. Rougher surfaces create more friction.
2. the forces that are pushing the two surfaces together. Greater force creates more friction.

4. TYPES OF FRICTION
Sliding Kinetic Friction – the type of friction produced when two solid objects slide over one another.

5. TYPES OF FRICTION
Rolling Kinetic Friction – the type of friction that occurs when an object rolls over a surface

6. TYPES OF FRICTION
Fluid Kinetic Friction – the type of friction that opposes motion when an object moves through a fluid (liquid or gas)

7. TYPES OF FRICTION
Static Friction – this happens when a force is applied to an object but the object does not move.
Static friction disappears as soon as the object starts to move.

8. HARMFUL OR HELPFUL?

9. WAYS TO REDUCE FRICTION
Use a lubricant. A lubricant is applied to surfaces to decrease the amount of friction between them.
Switch from sliding kinetic friction to rolling kinetic friction
Smooth surfaces that rub together

10. WAYS TO INCREASE FRICTION
Make surfaces that rub together rougher
i.e. putting sand on icy roads
Increase the force pushing the surfaces together

11. Friction Friction exists throughout the universe
It can be reduced but not eliminated
The closest frictionless environment would be space.
Space is a vacuum so there is no air resistance as long as there is no major gravitational force there is no natural pressure…but if an object comes in contact with another object there is friction