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The Ship Ladder Tide Riddle That Tricks Almost Everyone
A ladder hangs from a ship with 10 rungs spaced 30 cm apart; water touches the 3rd rung. The tide rises at 60 cm/hour. After 2 hours, which rung does the water touch?
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What is the answer to the ship ladder tide riddle?
The 3rd rung. The ship floats, so it rises with the tide and the ladder rises with it — the water level relative to the rungs never changes.
Why doesn't the water reach a higher rung as the tide comes in?
Because the ship is buoyant. As the tide lifts the water, it lifts the whole ship and its ladder by the same amount, so the same rung always sits at the waterline.
Is this a math riddle or a trick question?
It's a lateral-thinking trick question. The 60 cm/hour and 2-hour numbers are a distraction — physics, not arithmetic, gives the answer.