Friction is a force that opposes the motion of objects. It is caused by the interaction between two surfaces and can slow down or stop the movement of an object.
The amount of friction between two surfaces is affected by the roughness of the surfaces, the force pressing the two surfaces together, and the type of material the surfaces are made of.
The three main types of friction are static friction, kinetic friction, and rolling friction. Static friction occurs when two surfaces are not moving relative to each other. Kinetic friction occurs when two surfaces are sliding against each other. Rolling friction occurs when an object is rolling over a surface.
The force of friction can be calculated using the formula F = μN, where F is the force of friction, μ is the coefficient of friction, and N is the normal force (the force perpendicular to the surface).
The force of friction can be reduced by using lubricants, such as oil or grease, between two surfaces. It can also be reduced by using smoother surfaces or by decreasing the force pressing the surfaces together.