A solid ball with a mass m = 0.53 kg floats in a tank of water. The ball is made of material with a density of 400
kg/m3
. The density of water is 1000
kg/m3
. What fraction of the volume of the ball is below the waterline?
By the law of floatation, any floating object will displace a mass of fluid equal to its own mass.
So a floating object of volume 1 m³ density 400 kg/m³ will displace 400 kg of water, i.e. fraction of immersed object is 0.4, equal to its specific gravity, and independent of the mass of the object.