a woman exerts a constant horizontal force on a box. as a result, the box moves across a horizontal floor at constant velocity, the constant force by the woman has the same magnitude as the frictional force. could someone explain this to me? also why isn't the constant force exerted greater than the frictional force?

Question

a_clan · Answer

$$F _{woman} - F _{friction} = F _{net}$$
According to the question, F(net) =0
Had it not been zero, then the box should have had some acceleration [F=m.a], which is clearly not the case as the box is moving with constant velocity.

anonymous · Answer

The reason the constant force is not greater then the frictional force is because of Newton's first law of motion.  It basically states an object will either be at rest, OR moving at a constant speed when the net force on that object is zero (in other words the forces are balanced).

With the two forces being in opposite directions, this means they are balanced and by Newton's first law it has to be a rest or moving at a constant speed.