Suppose that a heavy person and a light person are balanced on a teeter-totter made of a plank of wood. Each person now moves in toward the fulcrum a distance of 25 cms. What effect will this have on the balance of the teeter-totter?

The light person's end will go down.

Explanation: Since they were both on equilibrium initially before the 25cm in moving. The moment they move in by 25cm each, the heavier person will be raised in air because the light person was supposed to be farther from the knife edge so as to maintain the balance, he now has more torque on the system.