The diameter of a roller is 84 cm and its length is 120 cm. It takes 500 complete revolutions to move once over to level a playground. Find the area of the playground in m^2? - Mathematics

The diameter of a roller is 84 cm and its length is 120 cm. It takes 500 complete revolutions to move once over to level a playground. Find the area of the playground in m2?

["Assume "pi=22/7]

Solution

It can be observed that a roller is cylindrical.

Height (h) of cylindrical roller = Length of roller = 120 cm

Radius (r) of the circular end of roller = (84/2)cm = 42cm

CSA of roller = 2πrh

=(2xx22/7xx42xx120)cm^2

= 31680 cm2

Area of field = 500 × CSA of roller

= (500 × 31680) cm2

= 15840000 cm2

=15840000/(100xx100) m^2

= 1584 m2

Concept: Surface Area of Cylinder
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APPEARS IN

NCERT Class 9 Maths
Chapter 13 Surface Area and Volumes
Exercise 13.2 | Q 4 | Page 217