Why is it that, when spraying an aerosol can of deodorant, it suddenly becomes very cold when it runs out?
Helena,
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Colchester, Essex, UK
When a round coin rolls down a slope, it stays upright, so why does a 鈥渟quare鈥� coin sliding down a slippery slope soon fall over?
Ed Stefaniuk,
Yarm, North Yorkshire, UK
To answer this question 鈥� or ask a new one 鈥� email lastword@newscientist.com.
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