6.20) Calculate the density of a fluid in which a hydrometer of uniform density 0.80g/cm^3 floats with 90% of its volume submerged.

Question

Note: Pls provide me an answer with relative solution/formula to this problem. Thanks!

Answer 1

the volume of fluid with the same mass as the hydrometer
... is 90% of the volume of the hydrometer

density = mass / volume
... for the hydrometer ... m / v = 0.80 g/cm^3
... for the fluid ... m / (.9 v) = (m / v) / .9 = (.80 / .9) g/cm^3