Question

the diameter of a roller is 84cm and it's length is 120cm it take 500 complete revolution to move once over to level a playground find the area of the playground in meter square

Answer 1

Amswer :


Given Diameter of roller = 84cm

Radius of roller = Diameter ÷ 2 = 84 ÷ 2 = 42cm

Given length or height of roller = 120cm

Area of Playground = Area covered by roller in 500 revolutions


Since the shape of roller is cylindrical

Therefore, Curved Surface Area of roller = 2πrh
where, r is radius and h is height.

$= > \: 2\pi rh \\ \\ = > \pi = \frac{22}{7} \\ \\ 2 \times \frac{22}{7} \times 42 \times 120 \\ \\ 2 \times 22 \times 6 \times 120 \\ \\ 44 \times 720 \\ \\ 31680 \: cm {}^{2}$

$area \: covered \: by \: roller \: in \: 1 \: revolution = 31680 {cm}^{2} \\ \\ area \: covered \: by \: roller \: in \: 500 \: revolutions = 31680 \times 500 \\ \\ = > 15840000 {cm}^{2} \\ \\ therefore \: area \: of \: playground \: in \: m {}^{2} = \frac{15840000}{100 \times 100} \\ \\ 1584 \: {m}^{2}$

Answer 2

hope it's help u dear..!!!