Friction is a very important force but it can also be very troublesome. Friction forces come into play when two surfaces are in contact with each other. The Space Shuttle, pictured on the right, travels at speeds of up to 25,000 Km/hr. At such speeds, the air molecules rub up against the body of the Shuttle and generates extreme friction that creates temperatures in excess of 1,000oC. Friction acts to slow the Shuttle down before landing.

Friction is very important. The absence of friction makes movement difficult on the surface of the Earth. Click to see a 120kb video.

We can also have a lot of fun in the absence of friction. Click to see a120kb video

A car is a fine example of the importance of friction and its troublesome nature. In order for the car to accelerate the tyres must grip the road firmly. This requires significant friction. However, friction reduces the performance of the engine. The engine has many parts that grind together and make contact with each other. Friction reduces the ability of these parts to move past each other and special oils are used in the engine to reduce friction.