Physics

You have a bag of cotton and an iron bar, each indicating a mass of $100kg$ when measured on a weighing machine. In reality, one is heavier than the other. Can you say which one is heavier and why?

SOLUTION
In reality , the cotton bag is heavier .
This is because the cotton bag has more volume than that
of an iron bar so it displaces more air and hence the buoyant
force acting on the cotton bag due to the air is more than that
acting on the iron bar (by Archimedes' principle) and
True weight = Apparent weight + Buoyant force
Apparent weight = $100$ kg for both but buoyant forces are different.

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Subjective Medium Published on 18th 08, 2020
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