Question

A canal is 300 cm wide and 120 cm deep. The water in the canal is flowing at a speed of 20 km/h. How much area will it irrigate in 20 minutes if 8 cm of standing water is desired?​

Answer 1

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The volume of water flows in the canal in one hour

= width of the canal × depth

of the canal × speed of the canal water

= 3 × 1.2 × 20 × 1000 m^3

= 72000m^3

In 20 minutes the volume of water

= (72000 × 20)/ 60 = 24000 m^3

Area irrigated in 20 minutes,

if 8 cm, i.e.,

0.08 m standing water is required

=24000/0.08

= 300000 m^2

= 30 hectares

Answer 2

Solution :

The volume of water flows in the canal in one hour:

• Width of the canal × depth of the canal × speed of the canal water

=> 3 × 1.2 × 20 × 1000 m³

=> 72000m³

In 20 minutes the volume of water

=> (72000 × 20)/ 60 = 24000 m³

Area irrigated in 20 minutes, if 8 cm, i.e., 0.08 m standing water is required

=> 24000/0.08

=> 300000 m²

=> 30 hectares