Friction is a force that opposes motion and occurs because surfaces are not perfectly smooth. Viewed under a microscope, surfaces show ridges which inhibit movement.
Friction has several uses. The friction between the wheels of a car or bicycle on a dry road enable it to move without sliding and friction in the braking system helps them to stop. Friction between ice skates and skis produces enough heat to temporarily melt the ice under the skates. Thus skaters and skiers travel on a thin film of water without which skates and skis would stick to the ice.
However, friction can be a hindrance to movement in machinery, such as the gear wheels on a bicycle. To overcome this we use lubricants.
- Slows moving objects down or prevents them moving.
- Produces heat. The moving surfaces heat up when there is movement between them.
- Causes surfaces to wear as they move together.
These can be reduced by:
- using smoother surfaces;
- reducing the pressure between two surfaces;
- using lubricants to create a smooth film between surfaces;
- reducing the area of the surfaces in contact with each other.
The effects of friction can be increased by:
- using rougher surfaces;
- increasing the pressure between surfaces;
- using materials that are less likely to easily slide together.
