Question

The internal and external radii of a spherical shell are 3cm and 5cm respectively. It is melted and recast into a solid cylinder of diameter 14 cm, find the height of the cylinder. Also find the total surface area of the cylinder. (Take `pi = 22/7`)

Answer 1

Volume of shell = Volume of cylinder

⇒ `(4pi)/3 [5^3 - 3^3] = pi(7)^2 h`

⇒ `h = 8/3 = 2 2/3 cm`

TSA of cylinder is

= `2pir(r + h)`

`= 2 xx 22/7 xx 7 xx (7 + 8/3)`

`= 44 xx 29/3`

`= 1276/3` cm² or 425.33 cm²