Question

The diameter of a roller is 2.5m and its length is 1.4m .How much area will it cover in 7 revolution.​

Answer 1

Given

• Radius of the roller = 2.5/2 m
• Length of the roller = 1.4m

To find

• Area will it cover in 7 revolution

Solution

As we know that

Curved surface area of roller

→ 2πrh

→ 2 × 22/7 × 2.5/2 × 1.4

→ 11m²

We know that

★ Area covered in one revolution = Curved surface area of roller

→ Area covered in 7 revolution = 7 × curved surface area

→ Area covered in 7 revolution = 7 × 11 = 77m²

Hence,

• Area covered in 7 revolution = 77m²

Answer 2

$\bigstar$ $\sf{\purple{\underline{\underline{\red{To\:Find:-}}}}}$

• How much area will roller cover in 7 revolution .

$\bigstar$ $\sf{\purple{\underline{\underline{\red{SOLUTION:-}}}}}$

☞ GIVEN:-

• The diameter of a roller (d) = 2.5m
• Length of Roller ( h / l ) = 1.4m
• No. of revolution = 7

╬ we have know that,

• $\tt{\:d\:=\:2\:r\:}$ (r = radius)

• $\tt{\implies\:r\:=\:{\dfrac{d}{2}}}$

• $\tt{\implies\:r\:=\:{\dfrac{2.5}{2}}\:\:=\:1.25\:m\:}$

╬ In 1 revolution, the area covered will be equal to the Curved Surface Area or CSA of the Roller

$\tt{\implies\:In\:1\:revolution,\:the\:area\:covered\:=\:2\:\times\:{\pi}\:\times\:r\:\times\:h\:}$

$\tt{\:=\:2\:\times\:{\dfrac{22}{7}}\:\times\:1.25\:\times\:1.4\:}$

$\tt{\:=\:11\:m^2}$

╬ In 1 revolution, it covers “11 m²” . Therefore in 7 revolutions , it will cover 7times of that .

╬ In 7 revolutions area covered ,

$\tt{\:=\:11\:\times\:7\:}$

$\tt{\:=\:77\:m^2}$

╬ Therefore it will cover 77m² in 7 revolutions .

$\bigstar\:\underline{\boxed{\bf{\red{Required\:Answer\::\:77\:m^2\:}}}}$