The coefficient of kinetic frictions between a 3.to kg box and a desk is 0.30.

May I ask, why are you asking this question?

Annalyse

I would guess... homework! :D

The force of friction acting on a body is given by the formula:



where F is the force of friction,
mu is the coefficient of friction,
R is the normal force acting on the body concerned.

First find the frictional force with the formula I gave you.

Then, remember that the net force is given by the vector addiction of all the forces acting on the body, and that the pushing 15 N force acts in opposite direction to the frictional force.

Post what you get! :)

Please explain in further detail. I am not following everything you're saying. Thanks:)

Could you tell more specifically what you are not understanding?

is called 'mu' and is a greek symbol, which is used in mechanics to represent the coefficient of friction.

R, the normal force is what prevents things to dig into the ground. The Earth pulls on everything and the ground pushes in the opposite direction so that the net vertical force is 0 and as there is 0 net force, there is no motion according to Newton's First law.

This is assuming you didn't understand what mu and R meant.