Question

derive angle of friction.

Answer 1

The coefficient of friction between any two surfaces in contact is defined as the ratio of the force of limiting friction and normal reaction between them.

u= F / R  

Angle with the resultant of force of limiting friction F and normal reaction R makes with the direction of normal reaction R is angle of reaction.

Answer 2

DERIVATION OF ANGLE OF FRICTION:

• Angle of friction is the angle between the resultant of frictional force and normal reaction and the normal reaction.
• It is also called limiting angle of friction

• Consider a block of mass m on a horizontal surface. Let F be the frictional force on the surface. N is the normal reaction acting upwards.  Let R be the resultant of these forces and ∅ be the angle between N and R. Here, ∅ is called as the angle of friction.    

• Coefficient of friction is the tangent of angle of friction.