Question

the diameter of a roller is 84 cm n it's length is 120 cm .it takes 500 complete revolutions to move once over to level a playground. find the area of playground in m^2

Answer 1

STEP 1: Convert cm to m:

84 cm = 0.84 m

120 cm = 1.2m

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STEP 2: Find the area covered in 1 revolution:

Area covered in 1 revolution = πD x length

1 revolution = π (0.84) (1.20)

1 revolution = 1.008π m²

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STEP 3: Find the area covered in 500 revolution:

1 revolution = 1.008π m²

500 revolution = 1.008π x 500

500 revolutions = 504π m²

500 revolutions = 1584 m²

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Answer: The area of the playground is 1584 m²

Answer 2

Hey there!!

A roller is in the shape of cylinder

First , let us find the radius

Diameter = 84

Radius = 42 ( diameter ÷ 2 )

Area of the roller = curved surface area of the cylinder

⇒ 2πrh

⇒ ( 2 ) ( 22 ÷ 7 ) ( 42 ) ( 120 )

⇒ 31680 cm²

This is for one revolution

For 500 revolutions = ( 500 ) ( 31680 )

⇒ 15840000 cm²

Now, convert this into m²

15840000 ÷ 10000

⇒ 1584m² is the area of the park

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