Question

An iron pillar consists of a cylindrical portion 2.8 m high and 20 cm in diameter and a cone 42 cm high is surmounting it. Find the weight of the pillar, given that 1 cubic cm of iron weighs 7.5 gm.

Answer 1

Volume of cylindrical portion

`=pir^2h`

`= 22/7 xx (20/2)^2 xx 280`

`= 88000 cm^3`

Volume of conical portion

`=1/3pir^2h`

` =1/3 xx 22/7 xx (10)^2 xx 42`

`=4400 cm^3`

Total number

`= 8800 + 4400`

`=92400`

So total height

`=92400 xx 7.5`

`= 693000 gm`

`= 693 kg`