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SURFACE AREAS

AND VOLUMES

Sum based on Cylinder

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Sol.

Area of ground pressed in 1 rev

= CSA of roller

0.45 m

1.8m

0.45m

1.8m

What is shape of roller?

Cylinder

What is area of ground pressed

by roller in one revolution?

It is same as

curved surface area of cylinder

Consider one revolution of roller

Q. A roller of diameter 0.9m and length 1.8m is used to

press the ground. Find the area of ground pressed by it in

500 revolutions. (π = 3.14)

0.9

2

Radius =

0.45 m

=

Let us find area pressed by

the roller in one revolution

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Area of ground pressed in 500 revolutions

∴ Area of ground pressed in 500 revolutions is 2543.4 m²

= 2πrh

= 2

×

3.14

×

0.45

×

1.8

= 6.28

×

0.81

= 5.0868 m²

= 500

×

5.0868

= 500

×

= 2543.4 m²

Area of ground pressed in 1 rev

= CSA of roller

Sol.

Q. A roller of diameter 0.9m and length 1.8m is used to

press the ground. Find the area of ground pressed by it in

500 revolutions. (π = 3.14)

0.9

2

Radius =

0.45 m

=

0.45 m

1.8m

What is the formula to find

curved surface area of cylinder?

2πrh

∴ Area of ground pressed in 1 rev

Area of ground pressed in 1 rev