Friction is a force that objects have which makes them resist
motion or movement across or against one another. If one object with a flat surface is placed
on top of another, the top object can be lifted with out any act of resisting except that of
gravity. If one object is pushed or pulled over another, there is an act of resistance that is
caused by friction. If one object moves over a stationary object, the stationary object will
slow down the moving object. If a force tries to move an object at rest on a surface, the surface
resists this motion with an opposing force of friction. The size or amount of the frictional
force depends on the kind of surfaces which are rubbing together.
Friction can be used for many important things such as helping the wheels of a
train stay on the rails of the track. It also allows a mechanical device that carries things from
one place to another also known as a conveyer; it helps the belt of a conveyor stay on pulleys
without slipping. We need friction to walk; if we did not have any friction, everything would be
slipping and sliding away. That is why we can't walk on ice very well; the ice is so smooth and
flat that it produces less friction than a sidewalk, making it hard to walk on ice.
Friction occurs any time when two objects or surfaces are rubbed together. The more the
pressure on the objects when they are rubbed together, the more friction. If you are trying to
slow down, friction works with you, but when you try to speed up, friction works against you.
Different methods can be used to reduce the amount of friction between the surfaces of the objects in contact.
One way to reduce friction is to apply a lubricant to the surfaces, another is to use casters,
rollers, or ball bearings between the surfaces, and another is to smooth the surfaces of the
objects in contact.