The angle of friction is
A. The ratio of friction and the normal reaction
B. The force of friction when the body is in motion
C. The angle between the normal reaction and the resultant of normal reaction and limiting friction
D. The force of friction at which the body is just about to move
Please scroll down to see the correct answer and solution guide.
Right Answer is: C
SOLUTION
Friction:
When one surface slides or tends to slide over another surface, resistance offered to the motion is known as friction. It is also called as a force of friction or frictional resistance.
Coefficient of friction (μ):
It is the ratio of the magnitude of limiting force of friction to the normal reaction between surfaces in contact
\({\rm{\mu }} = \frac{{{\rm{Limiting\;force\;of\;friction}}}}{{{\rm{Normal\;reaction}}}} = \frac{F}{R}\)
∴ F = μ R
The angle of friction (ϕ):
It is defined as the angle made by resultant reaction (S) with normal reaction (R).
We can see that
\(\tan \phi = \frac{{\rm{F}}}{{\rm{R}}} = \frac{{{\rm{\mu R}}}}{{\rm{R}}} = {\rm{\mu }}\)
∴ ϕ = tan-1 μ
The angle of repose (θ):
It is the maximum inclination at which a block placed on the inclined plane just begins to slide due to its own weight only.
