Section 2-5 What is friction?

The force that opposes the motion of an object. If you slide a book across a desk it will move in the direction that you are pushing it. As long as you continue to push (Force), it will move until the force of friction acts in the opposite direction and slows down the motion of the book and books comes to rest. Friction

 Sliding – kinetic like pushing a book across a desk  Air resistance – as object falls, air resistance pushes up on the object  Rolling – when you ride a bike, the contact between the wheel and the road Types of friction

Uses of friction Good  Without friction, motion would not be possible. When you ride a bike, friction keeps bike in motion  Friction helps stop items, like cars, trains, walking etc. Bad  Metal parts in a car engine are always touching, too much friction wears out the parts and overheats the engine

H.W. p. 29 Check/Apply 1-8 Wkst. 2-5