Q. 214.7( 3 Votes )

# Find the ratio of the weights, as measured by a spring balance, of a 1 kg block of iron and a 1 kg block of wood. Density of iron = 7800 kg m^{-3}, density of wood = 800 kg m^{-3} and density of air = 1293 kg m^{-3}.

Answer :

Given, Density of iron, ,

density of wood,

density of air

The objects can be thought of as fully immersed in air. Therefore, there will be a buoyant force working upwards.

Let mass of iron be and that of wood be . Let there volumes be and respectively.

The weight of iron block becomes, —————(1)

Similarly, weight of wooden block is —————(2)

Taking ratio of (1) and (2)

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