Night growth: I am told that we are measurably taller in the morning that when we go to bed. Can someone please explain this?
Axe axioms: The handles of felling axes are curved, whereas the handles of pickaxes, mattocks, sledgehammers, broad-axes and double-bitted axes are straight. What is the physical principle involved?
Bulb song: I have notice that household light bulbs sometimes develop a high-pitched hum before the filament fails. Can anyone suggest a mechanism for the humming?
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