Question

What is limiting friction and its laws ?

Answer 1

Hint: To solve this problem learn about the concepts of friction and its terminologies. Friction is a force and it always opposes the relative motion between the two objects.Friction provides traction that is needed to walk without slipping. Friction is useful in most cases, however, they also provide a great measure of opposition to the motion.

Complete step by step answer:
Limiting friction is defined as that type of friction which acts on a body when the body is at rest. To find limiting friction, we need to have the product of the normal force and the coefficient of limiting friction. The laws of limiting friction can be stated as:
-The direction of limiting friction force is always opposite the direction of motion.
-Limiting friction always acts tangentially to the two surfaces.
-It is dependent on the material and the nature of the both the surfaces in contact.
-It is independent of the shape and area of the body.

The value of limiting friction force is given by,
\[F = {\mu _{static}}N\]
where, \[{\mu _{static}}\] is the coefficient of limiting or static friction and \[N\] is the normal force acting on the body by the surface.

Note:The weight of the body always acts vertically downwards. So, provides the necessary normal force when placed on a surface as a reaction force. Friction is in times of great use since it helps us in so many daily works like walking, writing in a piece of paper or in application of brakes in cars, trains, buses etc. but it also costs us a lot of energy in most motions like the motion of cars, buses, trains. Even there is friction in motion of planes and spaceships before leaving the atmosphere; this friction follows a different formula though.