A uniform meterstick balances on a fulcrum placed at the 60-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) 0.6W
E) 0.2W

Question

A uniform meterstick balances on a fulcrum placed at the 60-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) 0.6W
E) ​0.2W

Quizplus · Accepted Answer

The meterstick balances at the 60-cm mark, meaning the torques on either side of the fulcrum are equal. The weight W creates a torque of W * 40 cm (distance from 20 cm to 60 cm). The weight of the meterstick acts at its center of gravity, which is at the 50-cm mark, creating a torque of weight of meterstick * 10 cm (distance from 50 cm to 60 cm). Setting these torques equal gives: W * 40 = weight of meterstick * 10, solving for the weight of the meterstick gives 2W.

A Uniform Meterstick Balances on a Fulcrum Placed at the 60-Cm