Name: Necessity of Friction
Uploaded: 2019-07-19
Duration: 4 min 40 s
Description: This video enables students to learn about friction, friction used in routine activities, loss of energy in the form of heat due to friction.

Question

Define angle of repose and coefficient of friction. Establish a relation between them. What is the unit of coefficient of friction ?

Accepted Answer

Angle of repose: It is the maximum angle of inclination $(θ)$ of a plane with the horizontal plane, at which, a body resting on it, is at the point of sliding downward by the action of its own weight.

Coefficient of friction $(μ)$ : It is a measure of the amount of friction existing between two surfaces. A low value of the coefficient of friction indicates that the force required for sliding to happen is less than the force required when the coefficient of friction is high. It is given by

$μ = \frac{F}{N}$ (Here, $F =$ Frictional force and $N =$ Normal force).

Since coefficient of friction is the ratio of two similar kinds of quantities, so it is dimensionless.

Let $m$ be the mass of the body, $g$ is the acceleration due to gravity and $N$ is the normal reaction. Then,

$m g \sin θ = μ N$

Where $μ$ is the coefficient of friction.

$N = m g \cos θ$

Now,

$m g \sin θ = μ m g \cos θ \tan θ = μ θ = \tan^{- 1} (μ) .$

Define angle of repose and coefficient of friction. Establish a relation between them. What is the unit of coefficient of friction ?

Important Questions on Equilibrium of Concurrent Forces and Friction

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