The diameter of a cylindrical roller is $84$ cm and length $1$ m. Find the area covered (in $\text{m}^{2}$)…
The diameter of a cylindrical roller is $84$ cm and length $1$ m. Find the area covered (in $\text{m}^{2}$) in one complete revolution. Use $\pi=\dfrac{22}{7}$.
$2.64 \text{ m}^{2}$
$2.16 \text{ m}^{2}$
$5.28 \text{ m}^{2}$
$1.32 \text{ m}^{2}$
Solution
Convert: $r = 42$ cm $= 0.42$ m, length $= 1$ m. Area in one revolution $=$ CSA $= 2\pi r h = 2 \times \dfrac{22}{7} \times 0.42 \times 1 = \dfrac{44 \times 0.42}{7} = \dfrac{18.48}{7} = 2.64 \text{ m}^{2}$.