Finding Coefficient of Friction

Our aim in this experiment is to study the relationship between the force of limiting friction and normal reaction and find the coefficient of friction between the surface of a moving block and that of a horizontal surface.

First let’s understand the basic terms related to our experiment :

Friction : Friction is the force that represents the level of resistance (relative motion) between two objects which are in contact with each other.
Limiting friction : Limiting friction is the amount of friction experienced when a stationary object is about to move. To put it another way, it’s the least amount of force required to move a stationary item. It is the maximum amount of friction between two materials.
Normal reaction: The normal reaction is defined as the force that any surface exerts on any other object in contact perpendicular to the plane of contact.
Coefficient of friction : The coefficient of friction is the ratio of the resistive force of friction acting between two surfaces to the perpendicular force (normal reaction) pushing the objects. It is denoted by the Greek letter mu (?).

Now, lets focus on the Coefficient of friction,

The coefficient of friction can be classified into two types—coefficient of kinetic friction and coefficient of static friction. The coefficient of kinetic friction (a.k.a. coefficient of dynamic friction or coefficient of sliding friction) means that the objects in contact are already in motion relative to each other. In contrast, the coefficient of static friction (a.k.a. starting friction coefficient) means the objects are at rest with respect to each other.

The coefficient of friction can be calculated by using the formula:

? = F/N where, F = Frictional force , N = normal reaction

For calculating the coefficient of static friction (? s), we use:

? s= FLN here, FL= Limiting friction or maximum value of static friction, N = Normal reaction.

While for calculating the coefficient of kinetic friction (? k), we use

? k= FkN here, Fk= kinetic friction, N = Normal reaction.

Usually, ? s>? k.

The coefficient of friction is a unitless and dimensionless quantity.

FAQs on Finding Coefficient of Friction

Q.1: What is friction?

Ans. Friction is the force that resists the sliding or rolling of one solid object over another.

Q.2: What is the cause of friction?

Ans: The following are the causes of friction:
A) Adhesion between body surfaces,
B) Surface roughness,
C) Body deformation.

Q.3: What are the factors the coefficient of friction depends on?

Ans: The coefficient of friction depends on several factors, such as the nature of the surfaces, the presence or absence of lubricants or contaminants, the force applied to the surfaces, and the angle of the surfaces.