Question

$50$ circular plates each of diameter $14\mathrm{cm}$ and thickness $0.5\mathrm{cm}$ are placed one above the other to form a right circular cylinder. Find its total surface area.

Answer 1

Given,

$50$ circular plates each with a diameter $=14\mathrm{cm}$

The radius of circular plates $=7\mathrm{cm}$

Thickness of plates $=0.5\mathrm{cm}$

As these plates are one above the other, the total thickness of all the plates $=0.5x50=25\mathrm{cm}$

Hence, the total surface area of the right circular cylinder formed $=2\mathrm{\pi r}\times \mathrm{h}+2{\mathrm{\pi r}}^2$

$=2\mathrm{\pi r}(\mathrm{h}+\mathrm{r})$

$=2\left(\frac{22}{7}\right)\mathrm{x}7\mathrm{x}(25+7)$

$=2x22x32$

We get, Total surface area $=1408{\mathrm{cm}}^2$

Therefore, the total surface area of the cylinder is $1408{\mathrm{cm}}^2$