A uniform meterstick balances on a fulcrum placed at the 40-cm mark when a weight W is placed at the 20-cm mark.What is the weight of the meterstick?
A) W
B) 2W
C) W/2
D) 0.4W

Question

Quizplus · Accepted Answer

The meterstick balances at the 40-cm mark, meaning the torques on either side are equal. The weight W creates a torque of W * 20 cm. For the meterstick to balance, its weight must create an equal torque on the other side. Since the center of mass of the uniform meterstick is at the 50-cm mark, the torque due to the meterstick's weight is its weight times 10 cm. Therefore, the weight of the meterstick is 2W.

A Uniform Meterstick Balances on a Fulcrum Placed at the 40-Cm