"Question 4 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 ?
Class 9 - Math - Surface Areas and Volumes Page 217"
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Answered by
4
Length of the roller (h) = 120 cm = 1.2 m
Radius of the cylinder = 0.42 m
Total no. of revolutions = 500
Distance covered by roller in one revolution = Curved surface area = 2πrh
= (2 × 22/7 × 0.42 × 1.2)
= 3.168 m2
Area of the playground =
500 × 3.168 => 1584 m2
Radius of the cylinder = 0.42 m
Total no. of revolutions = 500
Distance covered by roller in one revolution = Curved surface area = 2πrh
= (2 × 22/7 × 0.42 × 1.2)
= 3.168 m2
Area of the playground =
500 × 3.168 => 1584 m2
Answered by
3
diametre of rollar = 84 cm
radius of rollar (r) = 42 cm
Length of rollar ( L) = 120 cm
surface area of rollar = surface area of cylinder = 2πrL
= 2 × 22/7 × 42 × 120 cm²
= 12 × 22 × 120 cm²
= 31680 cm²
total area of playground= 500× surface area of rollar
= 500 × 31680 cm²
= 15840000 cm²
= 15840000× 1/(10²)² [ 10² cm = 1 m ]
= 1584 m²
radius of rollar (r) = 42 cm
Length of rollar ( L) = 120 cm
surface area of rollar = surface area of cylinder = 2πrL
= 2 × 22/7 × 42 × 120 cm²
= 12 × 22 × 120 cm²
= 31680 cm²
total area of playground= 500× surface area of rollar
= 500 × 31680 cm²
= 15840000 cm²
= 15840000× 1/(10²)² [ 10² cm = 1 m ]
= 1584 m²
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