Writing

2021CZ

Stir or blow?

The fastest way to cool a spoonful of soup — and whether stirring secretly warms it.

Blowing wins, 65 °C in 80 s, but it only chills the surface; stirring cools the whole bowl.

Cooling curves with exponential fits, plus a poll of 278 people.

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2022CZ

A kilo isn't a kilo

Feathers, iron, and a helium balloon walk onto a scale in open air.

In air they can't both read a kilo — buoyancy gets a vote. The helium balloon is the heavier one, and most people guess wrong.

No experiment needed; the experimental section is famously left to the reader.

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