“Physics Teasers” — Google Groups/rec.puzzles

URL: https://groups.google.com/g/rec.puzzles/c/_6joasswgO4

Exact question, worked solution and final answer. The complete barge-and-lock problem is reproduced, followed by a detailed displacement calculation accounting separately for the barge’s rise and the lock’s changing water level. Match: exact. Exposure confidence: high. Correctness confidence: high. This pushes independently verified answer exposure back from later forum discussions to 1993.