SURFACE AREAS

AND VOLUMES

• Sum based on Cylinder

Sol.

1 min

Radius =

= 3.5 cm

Volume of water flowing in 1 min

= 192.5 litres

=

11550000 cm³

1 hour

17. A cylindrical pipe has inner diameter of 7 cm and water flows through

it at 192.5 litres per minute. Find the rate of flow in kilometers

per hour.

Volume of water flowing in 1 hour

=

192.5

×

60

=

11550

×

1000

litres

cm³

h = ?

Volume of water flowing in 1 hour

Volume of water flowing 1 hour

=

π r² h

11550000

i.e. Distance covered

by water in 1 hour ?

We know that,

1 litre = 1000 cm³

Let us observe water flowing in 1 hour

Let us calculate volume of water flowing in 1 hour

=

Vol. of cylinder

3.5 cm

What is formula to find volume of cylinder ?

π r² h

Sol.

17. A cylindrical pipe has inner diameter of 7 cm and water flows through

it at 192.5 litres per minute. Find the rate of flow in kilometers

per hour.

1155

×

7

×

2

×

2

22

×

7

×

7

h =

2

∴

h

=

15

×

10000

×

2

∴

11550000

=

×

×

h

×

h = ?

=

π r²h

11550000

3.5 cm

105

11550000

×

7

×

2

×

2

22

×

7

×

7

h =

∴

× 10000

15

∴

Radius =

= 3.5 cm

Sol.

17. A cylindrical pipe has inner diameter of 7 cm and water flows through

it at 192.5 litres per minute. Find the rate of flow in kilometers

per hour.

∴

∴

h

=

300000 cm

h

=

3 km

The rate of flow of water is 3 km per hour.

∴

1 km = 100000 cm

100000

∴

h

=

300000

3.5 cm

h = ?

h

=

15

×

10000

×

2