Calculating Frictional Force in a Sliding Box Experiment

[laughingcat]

A small girl applies a horizontal force of 2 Newtons to a 10-Newton box which slides
across the floor with a constant speed of 3 m/s. What is the frictional force, in Newtons,
by the floor on the box?


F=ma


The correct answer is 2 but I don't understand why. If the horizontal force is 2 and the frictional force is 2, wouldn't the box not slide? Indicating that the velocity is constant means that there is no acceleration correct?

 

[rl.bhat]

If the frictional is the maximum force which is needed to start the motion. If the applied force is just equal to the frictional force, the body will move with uniform velocity.

 

[laughingcat]

oh! thank you!