Question

antsy andy tries to push his 6kg desk away from him and finds that it takes him 12 N of force to start the desk from rest and 8 N to keep it moving at constant velocity. what are the coefficients of static and kinetic friction?

Answer 1

Answer:

static coefficient = 0,203 & kinetic coefficient = 0,14

Explanation:

There are two (2) conditions, when the desk is about to move and when the desk is moving. In the attachements you can see the two free body diagram for each condition.

In the first condition, there is no movement and the force is 12 N, in the image we can see the total forces are equal to 0 and by the definition of the friction force we can get the static friction coefficient.

In the second condition there is movement in the direction of the force which is equal to 8 N, again by the definition of the friction force we can get the kinetic friction coefficient. Since the desk is moving with constant velocity there is not acceleration.