Chapter 12-3 Part 2 Friction: A Force That Opposes Motion Pages 352 - 355

Types of Friction 1. Sliding friction - the friction on an object sliding over a surface.

2. Rolling friction- the friction on an object rolling on wheels (less friction than sliding friction).

3. Fluid friction- The friction on an object moving through a fluid (less friction force than sliding friction).

4. Static friction - the friction on a stationary object that prevents it from moving.

Ways to Change Friction 1. To reduce friction: *use a lubricant (oil, wax, grease) *switch from sliding to rolling friction *make surfaces smoother 2. To increase friction: *make surfaces rougher *increase force pushing surfaces together

Harmful and Helpful Friction makes it possible to move a car forward and for the brakes to stop the car. Friction between moving engine parts increases their temperature and causes the parts to wear down.

Imagine that you have been asked to design a bowling alley Imagine that you have been asked to design a bowling alley. Describe the areas you would try to reduce friction and the areas where you would try to increase friction.

Let’s Try It! LAB: Science Friction