Question

A 0.52 kg piece of wood floats in water but is found to sink in alcohol (specific gravity = 0.79) in which it has an apparent mass of 0.040 kg. What is the SG of the wood?

Answer 1

The specific gravity must be between 1.00 and 0.79 if it sinks in water but not in alcohol.

The apparent mass in alcohol is
V*(wood density) - V*(alcohol density) = 0.040 kg ..after subtracting the bouyant force.

Wood density = alcohol density + 0.040 kg/V = 790 kg/m^3 + 0.040 kg/V

Wood density = 0.52 kg/V

0.48 kg/V = 790 kg/m^3

V = .000608 m^3 = .608 liters

S.G = 0.52 kg/.608 l = 0.855