Two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque?
A) the first at the midpoint
B) the second at the doorknob
C) both exert equal non-zero torques
D) both exert zero torques
E) Additional information is needed.

Question

Quizplus · Accepted Answer

The torque depends on both the magnitude of the force and the distance from the pivot point (in this case, the hinge) where the force is applied. The force applied at the doorknob is farther away from the hinge than the force applied at the midpoint, which means it has a larger lever arm and produces a greater torque. Therefore, choice B is correct.

Two Equal Forces Are Applied to a Door