Question

The diameter of a garden roller is 1.4 m and it is 2 m long. Total area covered in 5 revolutions is

• A. $4.4{\text{m}}^2$
• B. $8.8{\text{m}}^2$
• C. $44{\text{m}}^2$
• D. $84{\text{m}}^2$

Answer 1

The correct option is C $44{\text{m}}^2$

A roller is cylindrical shaped.
Height (h) of the cylindrical roller = length of roller = 2 m
Diameter of the roller = 1.4 m
$\Rightarrow$ Radius (r) of the roller = 0.7 m

We need to calculate the area covered in 5 revolutions of this roller.

$\text{Area covered}=\text{CSA of the roller}\times \text{Number of revolutions}$

We know, CSA of a cylinder with radius 'r' and height 'h' is $2\pi rh$.
$\text{Then, CSA of the roller}=2\times \frac{22}{7}\times 0.7\times 2=8.8{\text{m}}^2$

Hence,
Area covered $=(8.8\times 5){\text{m}}^2=44{\text{m}}^2$