Friction
Friction is a force between two surfaces that are sliding, or trying to slide, across each other.
Friction always slows a moving object down. Air resistance is a type of friction. |
What to do!
1. Read the information. 2. Complete the quiz. 3. How is friction used in everyday life? Create a poster on friction. |
What is friction?
Friction is a force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor friction makes this difficult.
Friction always works in the direction opposite from the direction the object is moving, or trying to move. Friction always slows a moving object down. More or less friction The amount of friction depends on the materials from which the two surfaces are made. The rougher the surface, the more friction is produced. For example, you would have to push a book harder to get it moving on a carpet than you would on a wooden floor. This is because there is more friction between the carpet and the book than there is between the wood and the book. Heat Friction also produces heat. If you rub your hands together quickly, you will feel them get warmer. |
Useful friction and reducing friction
Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road.
When you walk, friction is caused between the tread on shoes and the ground. This friction acts to grip the ground and prevent sliding.
When you walk, friction is caused between the tread on shoes and the ground. This friction acts to grip the ground and prevent sliding.
Ice causes very little friction, which is why it is easy to slip over on an icy day. However this is a good thing for ice skating and sledging.
Reducing friction Sometimes we want to reduce friction. For example, we use oil to reduce the friction between the moving parts inside a car engine. The oil holds the surfaces apart, and can flow between them. The reduced friction means there is less wear on the car's moving parts, and less heat produced. |