Which simple machine's operations are governed by equal torque on both sides and is exemplified by a seesaw?

• A. Pulley
• B. Lever
• C. Inclined plane
• D. Wedge

Answer: (B)

Rotational equilibrium happens when torques around a pivot cancel each other. A seesaw is a lever with a fixed fulcrum in the middle, so each side’s weight creates a torque equal to the force times its distance from that pivot. When those torques balance, the lever stays level. That’s exactly the situation on a seesaw: the two sides balance when the products of weight and distance on each side are equal. The other options involve different ways of using force—not balancing around a central pivot with equal torques—so they don’t describe a seesaw’s operation.