Friction : Friction Friction is a force that opposes motion between two surfaces that are touching.
For the force of friction to act between two objects, the objects must be touching.
Sliding Friction : Sliding Friction Sliding Friction occurs when an object slides against a surface.
When you slide an eraser over a desk the eraser will travel for a short distance and then stop because of sliding friction.
Rolling Friction : Rolling Friction When you push a shopping cart through a supermarket, the force of the cart pushing back on you results mainly from rolling friction.
The friction between the wheels and the surface is called rolling friction.
Fluid Friction : Fluid Friction Fluid friction opposes the traveling of objects through a liquid.
Liquids (water and milk)
Gases (Air and helium)
Bicycle racers bend low over their bikes in order to reduce the force of fluid friction.
Static Friction : Static Friction When a force is applied to an object and the object does not move static friction has occurred.
The object does not move because the force of static friction balances the force applied.
Suppose you want to move a refrigerator. You push on the refrigerator, but it does not move. The refrigerator is pushing back on you with the force of static friction.
Lubricants : Lubricants Lubricants are substances applied to the surfaces of objects to help reduce friction between them.
Increasing Friction : Increasing Friction Ways to increase friction might be making the surface rougher.
Sand scattered on icy roads to keep cars from skidding.
A golfer wearing a glove to keep a good grip on the golf club.