Mass density is the measure of the amount of mass per unit volume of a substance. It is often denoted by the Greek letter rho (ρ) and is expressed in units of kilograms per cubic meter (kg/m3).
Mass density plays a crucial role in determining an object's buoyancy. If the mass density of an object is greater than the mass density of the fluid it is placed in, it will sink. On the other hand, if the mass density of the object is less than the mass density of the fluid, it will float.
The mass density of an object is affected by its composition and the arrangement of its molecules or particles. The temperature and pressure can also affect the mass density of a substance.
Specific gravity is the ratio of the mass density of a substance to the mass density of water. It is a unitless quantity and is often used to compare the density of different substances. The higher the specific gravity, the denser the substance is compared to water.
Mass density can be measured using various techniques, such as the mass/volume method, which involves measuring the mass of a substance and its volume and then calculating the density. Other methods include using specialized instruments like a hydrometer or a pycnometer to measure the density of liquids or solids, respectively.