1. C. Friction Friction  force that opposes motion between 2 surfaces  depends on the: types of surfaces force between the surfaces

2. C. Friction Friction is greater...  between rough surfaces  when there’s a greater force between the surfaces (e.g. more weight) Pros and Cons?

3. Types of Friction Static = occurs between 2 surfaces that touch but do not move in relation to each other

4. Sliding = occurs when one object slides over another.  Weaker than static  Causes heat

5. Rolling = occurs between the surface of a round object and another surface.  Weaker than sliding  Less heat produced

6. Fluid friction = friction that opposes the motion of objects traveling though a liquid or gas.

7. Reducing friction Use a lubricant Change the type of friction involved Make surfaces that touch smoother  Is friction always a problem?  How could you increase friction?