Q10 of 45 Page 11

The diameter of a roller is 84 cm and its length is 120 cm. It takes 500 complete revolutions moving once over to level a playground. What is the area of the playground?

Given: Diameter = 84 cm


Length = 120 cm


To find: Area of playground


Formula Used:


CSA of cylinder = 2πrh


Explanation:


Diameter of roller = 84 cm


Radius of roller =


Length of roller = 120 cm


When a wheel of roller rotates completely, it covers certain distance.


Hence, it can be used to find the area covered by it.
Also a wheel will take certain rounds to cover some distance.


If roller moves in whole playground,


Area of playground = Curved surface area of roller × Number of revolutions


Curved surface area of roller = 2πrh



=31680 cm2


No. of revolution it takes to level the ground=500


Hence,


Area of playground = 500 × 31680


= 15840000 cm2



= 1584 m2


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