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?