Two equal-magnitude forces are applied to a door at the doorknob. The first force is applied perpendicular to the door, and the second force is applied at 30° to the plane of the door. Which
Force exerts the greater torque about the door hinge?
A) Both forces exert zero torque.
B) Both forces exert equal non-zero torques.
C) the first force (applied perpendicular to the door)
D) the second force (applied at an angle)

Question

Quizplus · Accepted Answer

The torque exerted by a force depends on the magnitude of the force, the distance from the pivot point (in this case, the door hinge), and the angle at which the force is applied. The first force, being applied perpendicular to the door, exerts a greater torque because the effective lever arm is maximized and the entire force contributes to the torque. The second force, applied at an angle, has a component that acts parallel to the door and does not contribute to the torque, making its effective torque less than that of the first force.

Two Equal-Magnitude Forces Are Applied to a Door at the Doorknob