Puzzles
Lewis Carroll's Monkey on a Rope
A rope runs over a frictionless pulley. A weight hangs from one end; a monkey hangs from the other, exactly balancing it. The monkey starts climbing the rope. What happens to the weight — does it rise, fall, or stay level with the monkey?
Reveal the answer
The weight rises in lockstep with the monkey — at every instant they move with the same speed, so the two stay level throughout the climb. Lewis Carroll posed this deceptively simple mechanics puzzle in his diary in December 1893 and was delighted it split professional mathematicians into incompatible camps. Sam Loyd later reprinted it in his 1914 Cyclopedia of Puzzles — with the wrong answer.
— Lewis Carroll, The Diaries of Lewis Carroll — Diary entry, 21 December 1893