Problem 4. Wobbly bridge

Statement

A horizontal metal ruler extends into the air and is supported just at one end, like a cantilever bridge. A plastic cup is attached to the other end of the ruler. Water droplets fall into the cup from a dropper at regular time intervals. Motionless at first, the bridge starts oscillating up and down, and then again comes to rest. Investigate and explain this effect.

Statistics

Number of reports: 2

Number of rejections: 1

Average Reporter Grade: 15.9

Average Opponent Grade: 13.1

Average Reviewer Grade: 6.3