The upper part of a solid right circular cylindrical pillar is a hemisphere . What will be the volume of the pillar it the radius of base of it is 2 metres and its total length is 10 metres ?

Explanation

Since the radius of base is 2 metres , so the radius of the hemisphere of the upper part of the pilar is 2 metres .
` :.` the height o the cylindrical part = `(10-2)` metres = 8 metres
Now, the volume of the hemisphere ` = 1/2 . 4/3 xx pixx 2^(3)` cubic - metre
` = 16/3` pi cubic - metre
and the volume of the cylindrical part ` = pi xx (2)^(2) xx 8 ` cubic - metre = `32 pi` cubic - metre
` :.` the total volume ` ( 16/3 pi + 32 pi )` cubic - metre
` = pi (16/3 + 32 ) ` cubic - metre
` pi xx 112/3 `cubic - metre
` = 22/7 xx 112 / 3` cubic - metre
` 352 / 3 ` cubic - metre = ` 117 1/3 ` cubic - metres
Hence the total volume of the pillar = ` 117 1/3 ` cubic - metres .