Friction

Friction is defined as resistance to motion between two surfaces. It distinguishes four types of friction:

• Statica – connecting force between two surfaces at rest
• Slip – resistance to motion between two bodies moving toward each other
• Rolling – resistance to movement of an object that is rolling out (a ball, a cylinder, a wheel etc.)
• Internal – resistance movement manifested in elastic bodies (tires heat up as a result of internal friction caused by deformation of the tire)

The quantity of friction between two surfaces depends on the following factors:

• substance / material from witch surfaces are made of
• surface roughness
• normal force that pushes surfaces one towards the other
• the presence of lubricants

The tyres must have good grip (a high friction) so that they do not slide on the road surface.
The quantity of friction between two surfaces is called coefficient of friction.
The energy lost to friction is turned into sound and heat.
This article is closely related with Coefficient of friction.