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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`)
Solution
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
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