Question

The diameter of a roller 21 cm long is 240 cm. What is the area covered by the roller
in one revolution?

11740 cm2
12520 cm2
30000 cm2
15840 cm2​

Answer 1

Answer:

The garden roller must look something like this —

d=2r

r=d2

r=1.42=0.7m

In 1 revolution, the area covered will be equal to the Curved Surface Area or CSA of the cylinder.

In 1 revolution, area covered = 2×π×r×h

I’m assuming the value of π to be 227

=2×227×0.7×2

=8.8m2

In 1 revolution, it covers 8.8m2 . Therefore, in 5 revolutions, it will cover 5 times of that.

In 5 revolutions, area covered = 8.8×5=44m2

Therefore, it will cover 44m2 in 5 revolutions.

Hope this helps.