Question

A right circular cylinder tunnel of diameter $2\text{m}$ and length $40\text{cm}$ is to be constructed from a sheet of iron. The area of the sheet required in${\text{m}}^2$ is

• A. $\frac{4}{5}\pi$
• B. $80\pi$
• C. $160\pi$
• D. $200\pi$

Answer 1

The correct option is A $\frac{4}{5}\pi$

Area of the required iron sheet $=$ Curved surface area of the cylinder

$\because$ Curved surface area of cylinder $=2\pi rh$

$⟹$ Area $=2\pi \times \frac{40}{100}$ $[\because 1\text{m}=100\text{cm}$ and $r=\frac{D}{2}=\frac{2}{2}=1\text{m}]$

$⟹$ Area $=\frac{4\pi }{5}{\text{m}}^2$