Question

the diameter of a roller is 2.5 metre and its length is 1.4 M how much area will it cover in seven revolution

Answer 1

Q. The diameter of a roller is 2.5 metre and its length is 1.4 M how much area will it cover in 7 revolution?

Radius of the roller (cylinder) = $\frac{2.5}{2}$

Length of the roller = 1.4m

Curved surface area of the roller = 2πrh

= 2 × $\frac{22}{7}$ × $\frac{2.5}{2}$ × 1.4

= 11 m²

We know that,
Area covered in one revolution = Curved surface area

Therefore,
Area covered in 7 revolution = 7 × Curved surface area

= 7 × 11 = 77 m²

Hence, the roller will cover 77m² in 7 revolution.

Answer 2

Given:

Diameter of the roller = 2.5 m

Length = 1.4 m (Height)

To Find : Area covered by it in 7 revolutions

Solution :

First of all we have to find it's Curved surface area .

Curved surface area of a cylinder= 2πrh = πdh
=
$\frac{22}{7} \times \frac{25}{10} \times \frac{14}{10} \\ \frac{11}{1} \times \frac{1}{1} \times \frac{1}{1} \\ \frac{11}{1}$ = 11 m²
Total Surface Area = 11 m².

Distance covered by it in 7 revolutions = 7×11= 77 m².

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