Question

Water in a canal, 30 dm wide and 12 dm deep, is flowing with a velocity of 20 km per hour.
How much area will it irrigate in 30 min. if 9 cm of standing water is desired ?

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Answer 1

Step-by-step explanation:

depth = 12dm = 1.2m

width = 30dm = 3m

flow velocity = 20km/h = 20,000 m/h

time = 30minute = 0.5 hour

standing water required = 9cm = 0.09m

Let the area = A m²

Volume of water will be same

1.2m × 3m × 20,000 m/h × 0.5 h = A × 0.09

⇒ A = 36000/0.09

⇒ A = 4,00,000 m² = 40 hectare

40 hectare plot can be irrigated

     

Answer 2

Step-by-step explanation:

vol. of canal in 30 min= 30m*12m*20000*30/60=3600000m^3

area irrigated in 30 min= vol. of canal in 30 min/9/100=40000000m^3