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Weight of nothing in an elevator (Posted on 2018-09-06) Difficulty: 3 of 5
Take an electronic kitchen scale, a scale with a spring dial, and a balance scale into an elevator.

Put nothing on them. Indeed, press the tare button, or adjust them so that they all read zero.

When the elevator accelerates upwards, what happens?

No Solution Yet Submitted by Jer    
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Some Thoughts proposed solution | Comment 1 of 6
During acceleration, this acts just like an increase in the force of gravity (as per Einstein's insight). The balance scale will still balance as the forces pulling down on each side will be multiplied by the same amount.

On the spring scale, the extra downward force will register as an increase the effective weight of whatever pan and support structure there is and cause the scale to show a higher weight. When the acceleration stops the spring will spring back and overshoot the zero mark and then come back with the oscillations dying out due to friction.

It's assumed that the electronic scale works on the piezo-electric compression forces on crystals. Presumably these would work much the same way as the spring scale, but on a smaller scale. However, even the small scale oscillation would presumably be interpreted as weight changes as large as those on the spring scale. But also, however, there might be some intelligence built into the device to lock the initial reading that was taken during acceleration to prevent the maximum weight from disappearing until the oscillations had died down.

  Posted by Charlie on 2018-09-06 10:54:35
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