The example of hollow cylinders is pipes, circular buildings and bearing bushes, etc. If is the outside radius of the cylinder and is the inside radius of the cylinder, then
and being outer and inner diameter, is volume.
A well with 10m inside diameter dug 14m deep. Earth taken out of it is spread all round to a width of 5m to form an embankment. Find the height of the embankment.
Volume of the dug out
Area of the embankment (shaded)
Height of the embankment
A hollow cylinder copper pipe is 21dm long. Its outer and inner diameters are 10cm and 6cm respectively. Find the volume of copper used in making the pipe.
Height of cylindrical pipe,
Volume of the copper used in making the pipe