Question

two people push on the same door from opposite sides as shown. they will only see the door move when

• both people exert the same force so that the forces are unbalanced.
• neither person exerts a force on the door so that the net force is zero.
• one person exerts more force than the other so that the forces are unbalanced.
• both people exert the same force so that the forces are balanced.

Explanation:

Motion occurs when net force is non-zero (unbalanced forces). If forces are equal (balanced), net force is zero, so no motion. If one force is larger, forces are unbalanced, creating a net force that moves the door.

Answer:

C. one person exerts more force than the other so that the forces are unbalanced.