The density of a substance is defined as its mass per unit volume. d = m / V
The relative density (R.D.) of a substance is the ratio of the density of the substance to the density of water at 4oC.
Relation between density and Relative density, Density in g cm 3 = R.D.
Density in kg m3 = R.D x 1000. This is because the relative density = density of substance/ density of water at 4oC. Learn to determine the relative density of a solid by Archimedes' principle
Why a loaded ship is more submerged while an unloaded ship is less submerged. This is because when a body is immersed in a liquid, the following two forces act on it :
(i) The weight W of the body acting vertically downwards, through the centre of gravity of the body. This force has a tendency to sink the body. (ii) The upthrust acting vertically upwards, through centre of gravity, called centre of buoyancy. The upthrust is equal in magnitude to the weight of liquid displaced. This force has a tendency to make the body float.
1)When weight of body is greater than buoyant force ,body will sink.
2)When weight of body is equal to the buoyant force or equal to the weight of liquid displaced, the body will float just inside the surface of the liquid.
3) When weight of body is less than buoyant force, the body will float partially above the surface of the liquid.
Learn more about why objects float and sink in a liquid.
Floatation and Relative density
Learnhive Lesson on Floatation and Relative Density