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You have a bag of cotton and an iron bar, each indicating a ma... - Science
Question
You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than other. Can you say which one is heavier and why?
Answer
The bag of cotton is heavier in reality.
Reason:
The volume of the cotton bag is much larger than the iron bar, so it displaces more air.
Therefore, the upward buoyant force exerted by the air is greater on the cotton bag.
The weighing machine measures the apparent weight (Actual Weight − Buoyant Force). Since both show the same reading, the actual mass of the cotton must be greater than that of the iron to compensate for the larger upward lift caused by the air.