G3 Friction (On Grade)_01

What is friction? Friction is a force that opposes motion. It occurs between two surfaces that are touching. If they are not touching, friction will not occur. The surfaces must also be moving past each other. In other words, without motion or touching of the objects, there is no friction.

So is friction good or bad? The answer is that it really depends on the situation. Many times, friction restricts motion. Other times, you need friction for motion to occur.