1. FRICTION
Notes!

2. Friction
  Friction is a force that opposes motion between two surfaces that are touching and creates heat. Friction can be helpful or harmful depending upon the situation.

3. Types of Friction
1. Sliding- sliding across a surface. The friction is between object and surface.
Ex) sledding, braking, writing, etc.
2. Rolling- rolling across a surface (friction is between wheels and surface)
Ex) bike, train, car, skates, etc.
3. Fluid- liquids and gases.
Ex) swimming in water and air resistance against a car
4. Static- When a force is applied to an object, but the object does not move
Ex) person sitting on a chair

4. Rougher Surfaces = More Friction Smoother Surfaces = Less Friction
Greater Force = More Friction
Smaller Force = Less Friction

5. Preventing you from falling Wearing down parts on an engine Erosion
Helpful Friction
Harmful Friction
Brakes
Writing
Preventing you from falling
Wearing down parts on an engine
Erosion
Can cause you to fall
Ways to reduce Friction
Ways to increase Friction
Make surfaces smoother
Lubricants like oil, wax, or grease
Switch sliding to rolling friction
Sandpaper on wood
Make surfaces rougher
Increase force
Ice on a road, chains on tires, batting gloves.

6. Inertia= the tendency of objects to stay where they are until they are acted on by a force. Inertia must be overcome in order for an object to move.
Balanced Forces= do not cause a change in motion. Therefore, the object is either not moving or moving at a constant rate. When you subtract the forces they equal zero (=0) or have no net force. They are equal in size and opposite in direction.
Unbalanced Forces= do cause a change in motion. The object is in motion but not at a constant rate. When you subtract the forces they do not equal zero (>0), therefore creating a NET FORCE!