For example, lets us take a candle in the shape of solid cylinder, melt it and pour whole of the molten wax into another container shaped like a sphere. On cooling, you will obtain a candle in the shape of the sphere. The volume of the new candle will be the same as the volume of the earlier candle. This is what we have to remember when we come across objects which are converted from one shape to another, or when a type of liquid which originally filled a container of a particular shape is poured into another container of a different shape or size as you observe in the following figures.

To understand what has been discussed, let us consider some examples.

Example-14.A cone of height 24cm and radius of base 6cm is made up of modelling clay. A child moulds it in the form of a sphere. Find the radius of the sphere.

Solution : Volume of cone= 1 ́p ́6 ́6 ́24cm3
If r is the radius of the sphere, then its volume is 4/3pr³
Since the volume of clay in the form of the cone and the sphere remains the same, we have

Therefore the radius of the sphere is 6cm.