Question

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

Answer 1

 The heaviness of the bag can be given by density

density = mass / volume


Mass of both cotton bag and iron bag is same. But the volume of cotton bag is more than the iron bag.
Hence density is inversely proportional to volume. The bag of iron will be heavier

Answer 2

The bag of cotton is heavier than the bar of iron. The cotton bag has a larger air thrust than the iron bar. The weighing machine therefore indicates a smaller cotton bag weight than its actual weight.

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