Question

Two children are balanced on opposite sides of a seesaw. If one child leans inward toward the pivot point, her side will

(a) rise.

(b) fall.

(c) neither rise nor fall.

Short answer

The correct option is (a).

Step-by-step solution

Concepts

The torque equals the product of the force and the perpendicular distance of the force from the pivot point. When the force comes closer to the pivot point, the magnitude of the torque decreases.

Explanation

When the seesaw is at equilibrium, the net torque on it is zero, i.e., the torque due to the children on both sides of the seesaw creates the same torque at the pivot point.

If one child leans inward to the pivot point, her distance from the pivot point decreases. So, the torque produced by that child decreases.

Therefore, the seesaw rises in her side.