Question

Using a horizontal force of 200N we intend to move a wooden cabinet across a floor at a constant velocity. What is the friction force that will be exerted on the object

Answer 1

HELLO THERE!

We know, that F = ma (Force = Mass x Acceleration )

So, when a = 0 (constant velocity), F should be zero (because mass of the body is not zero).

But applied force, F = 200 N. For constant velocity, there is no acceleration of the cabinet. So, we can say that the net external force acting in the system should be equal to zero.

In the vertical direction, it's weight will nullify the normal reaction force due to the ground on the cabinet.

In the horizontal direction, the frictional force has to cancel the applied force of 200 N, so that no acceleration acts on the body and the body moves with constant velocity. So, the frictional force should be of the same magnitude as the applied force and in a direction exactly opposite to that of the applied force (as friction tends to oppose a motion, so its direction needs to be opposite to the applied force).

Hence, the magnitude of the frictional force should be 200 N, and it's direction should be opposite to that of the applied force.

HOPE THIS HELPS..

Thanks!