The upper portion of a cylindrical pillar is a hemisphere. If the radius of its base is 2 metres and its total length is 10 metres. Find out the volume of the pillar.

Explanation

Since the radius of the base is 2 meters, the height of the hemisphere on top of the pillar will be 2 metres.
`:.` the height of the cylindrical portion `= (10-2)` metres `= 8 ` metres
Now the volume of the hemisphere `= 1/2 * 4/3 * pi *(2)^(3)` cu.m` = (16)/(3) pi ` cu.m.
and the volume of the cylindrical portion `= pi * 2^(2)*8=32 pi` cu.m.
`:.` The total volume of the pillar `= ((16)/(3) pi + 32 pi) "cu-m" = pi (16/3 + 32) ` cu-m.
`= (22)/(7) xx (112)/(3)` cu- m . `= (352)/(3) ` cu-m. `= 117 (1)/(3)` cu - m .
Hence the required volume `= 117 (1)/(3) ` cu-m.