Question

while you push a box you begin to decrease the force you are exerting on the box. when will the box reach equilibrium? (1 point)
when the force you are exerting on the box is equal to 0.
the box will never reach equilibrium.
when the the force of the box becomes $f_{you\\ on\\ box}when the $f_{you\\ on\\ box}=-f_{box\\ on\\ you}$

Explanation:

Equilibrium occurs when the net - force on an object is zero. When pushing a box, the forces acting on the box include the force you exert on the box and other resistive forces (like friction). In an ideal situation, when the force you are exerting on the box is equal to 0, and assuming no other non - zero external forces are acting on the box, the net - force on the box is zero and it reaches equilibrium. Newton's third law states that $F_{you\ on\ box}=-F_{box\ on\ you}$ always holds true due to action - reaction pairs, but this doesn't necessarily mean the box is in equilibrium. The box can be in motion or have other forces acting on it even when this action - reaction pair relationship is satisfied.

Answer:

When the force you are exerting on the box is equal to 0.