Abox of weight 74 n is sliding on a horizontal surface at a constant velocity due to an external force f-> of magnitude 4.8 n. a normal force (n-> ) and a friction force (f-> ) also act on the box. what is the magnitude of the friction force?

74 n

2.4 n

69 n

4.8 n

9.6 n

Answer

4.8 N

If the box is moving with a constant velocity, then we can say that the system is in equilibrium. This is because if the external force (F->) was greater than other forces the box would be accelerating. This tells us that this force (F->) is just enough to overcome friction and so it must be equal to 4.8 N.

The normal force has no effect to the horizontal velocities or forces. It is equal to -Weight. That is -74 N. The negative sign shows that the force is in opposite direction.