Notes
Short write-ups on physics and engineering I find fun, and the odd riddle.
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October 2026 · Riddle
Riddle: 1,000 bottles and one is poisoned
One bottle out of 1,000 is poisoned, and rats can test them. How few rats do you need? A riddle about binary encoding.
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October 2026 · Riddle
Riddle: an open freezer in a sealed room
A perfectly insulated room holds a freezer, plugged in, with its door open. What happens to the room's temperature?
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October 2026 · Riddle
Riddle: carrying a couch up the stairs
Two people carry a couch up a flight of stairs, one at each end. Who carries more of the weight?
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July 2025 · Physics
Why a falling accelerometer reads 0 g
A watch in free fall accelerates at 1 g, yet its accelerometer reads 0. The short version of a talk I gave at Withings, with drops from the 7th floor and a turntable.