Question

a box is sitting on the floor. the box was then pulled with a force, ft. the box did not move. the free - body diagram of the box is shown. which describes the motion of the box based on the resulting free - body diagram? it is moving up with a net force of 20 n. it is moving to the right with a net force of 10 n. it is in dynamic equilibrium with a net force of 0 n. it is in static equilibrium with a net force of 0 n.

Explanation:

To determine the motion, we analyze the net force. In the vertical direction: \( F_g = -20N \) (gravity) and \( F_N = 20N \) (normal force), so net vertical force \( F_{net,y}=20 + (-20)=0N \). In the horizontal direction: \( F_t = 10N \) (pull) and \( F_f=- 10N \) (friction), so net horizontal force \( F_{net,x}=10+(-10) = 0N \). Total net force \( F_{net}=F_{net,x}+F_{net,y}=0N \). When net force is zero, an object at rest (or moving with constant velocity) is in static equilibrium (if at rest) or dynamic equilibrium (if moving with constant velocity). Since the box did not move initially and net force is zero, it remains at rest, so it is in static equilibrium with net force 0N.

Answer:

It is in static equilibrium with a net force of 0N.