Completely smooth surfaces are not found in the universe. When a cricket ball hits with greater force, it moves a greater distance. When an object is pushed only with a small force, it may not move at all. Some type of force sees that it acts on fixed objects, which opposes their movement or movement. Such opposing forces are known as friction forces. The surfaces of the objects look smooth. But it was found that the surfaces of all bodies are rough !. The blocking of the two surfaces occurs when they come into contact with each other.
There are several types of friction, such as static or limiting; dynamic or sliding or kinetic; and rolling friction. The maximum frictional force that exists in a body when it simply proposes to slide over the surface of another body is known as ultimate or static friction. The friction force that exists in a body when it moves slowly or slides over another body is known as dynamic or sliding or kinetic friction. The first is more than the first. For example, a horse must use more force to start a cart than to keep the cart moving!
When a rolling body, like a wheel, touches another surface, the friction experienced is called rolling friction. The rolling body slightly deforms the surface and vice versa. A sufficient air pressure in automobile tires can reduce rolling friction. To minimize deformation and rolling friction, train wheels and rail tracks are made of metal.
Friction does not depend on the contact area. But it depends on the nature of the contact surfaces, t. E. The type of materials, the smoothness, the degree of lubrication, etc. The coefficient of friction of two surfaces is the ratio of the fractional force (F) to the normal reaction (R). The experiment can also be proven.
There are several ways to reduce friction. These include: the use of compressed air as a lubricant, rationalization, polishing, the use of ball bearings for rolling friction, etc. Thin and thick oils are used in light and heavy vehicles, respectively, to minimize the effect of friction. In heavy and high-speed machines, solids, such as grease, are also used to reduce friction.
