Question

If a man is walking, the direction of friction is equal to:
(A) Opposite to the direction of motion
(B) Same as that of motion
(C) Perpendicular to the direction of motion
(D) 45 to the direction of motion

Answer 1

Hint When a man walks forwards, the foot moves backwards. The frictional force will always oppose the motion of an object. So if a body is moving in 1 direction, its frictional force will act in the opposite direction

Complete step by step solution
If a body is traveling in the x-direction, there would be a force that is acting in the direction opposite to its direction. This force is known as the frictional force. It depends on the coefficient of friction between the 2 surfaces and the normal reaction of that body perpendicular to the surface.
 \[f\, = \,\mu R\]
Where R is the normal reaction of the body.
So, when a man is walking in one direction, he is pushing the ground backward. This force is acting in an opposite direction to the force of friction which means frictional force acts in the forward direction.

Therefore the option with the correct answer is option B.

Note Frictional force may seem like evil but it is very necessary for daily life. For eg, we won’t be able to walk if there was no frictional force as we would slip. This would happen with vehicles as well, as the brakes won't work and they won't be able to stop.