physics
posted by completely lost! .
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?

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