Center of mass

• Mass is the amount of matter a substance contains. Its SI unit is the kilogram (kg). The mass of an object remains constant at all times and under all conditions.
• The measuring instruments of mass include various types of balance.
• The centre of mass is the mean location of all the mass in a system.
• Weight of the pull of the earth on an object and is measured in newton (N). The measuring instrument of weight is the spring balance.
• The weight of an object varies directly with the mass and inversely with the distance from the centre of the earth.
Volume is the amount of space occupied by an object and its SI unit is the cubic metre.
Liquids take the shape of the container in which they are placed. The volume of liquid is commonly expressed in litres (l) which is a sub-unit of cubic metre (m3).
The volume of liquid can be measured using instruments such as beaker, burette, pipette, measuring cylinder, etc.
Since the liquids do not have fixed volume, they are used to measure the volume of irregular solids. The volume of any solid submerged in liquid is equal to the liquid it displaces.
Density is the mass of a unit volume of a substance Density=Mass/Volume ; it is the measure of how closely the particles of a substance are spaced.
The unit for density is kg/m3 or g/cm3 and its symbol is ρ.
The relative density is defined as the ratio of the mass of any volume of a substance to the mass of an equal volume of water. It has no unit since it is a ratio.
The relative density is measured using the density bottle