When a lift starts going down, the floor falls away from her a little and she presses on the scales less hard. At a steady speed the stone comes back.
A woman steps into a small room, stands on a set of bathroom scales and presses a button. For a few seconds she weighs a stone less. How?
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The room doesn’t stay where it is.
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The room is a lift, and it’s going down
Source: Anonymous, via Arkadium