Question

An object of density 12g/ cm cube is weighed with brass weights of density 8 g/ cm cube by a physical balance.if the density of air is 12× 10 power minus 3 g/ cm cube then the % error in weighing will be

Answer 1

$<b>$where ∆W is fractional error in weighting, density of air , is density of object and is density of brass.

now,
∆W = 0.012/1.2 - 0.012/8
= 0.012[5/6 - 1/8]
= 0.012 × (40 - 6)/48
= 0.012 × 34/48
= 0.034/4
= 0.017/2
= 0.0085

so, % error = 0.0085 × 100 = 0.85 %