Question

Water in a canal, 6 m wide and 1.5 m deep, is flowing at a speed of 4 km/hr. How much area will it irrigate in 10 minutes if 8 cm of standing water is needed for irrigation?

Answer 1

We have,

Width of the canal, b = 6 m

Depth of the canal, h = 1.5 m,

Height of the standing water needed for irrigation, H=8 cm = 0.08 m,

speed of the flowing water, l=4 km / h `= 4000/60 = 200/3 "m"// "min"` 

Now,

Volume of water flowing out from canal in 1 min =lbh

`=200/3xx6xx1.5`

=600 m²

⇒ Volume of water flowing out from canal in 10 min = 600 × 10 = 6000 m³ 

`"so, the area of irrigation" = "Volume of water flowing out from canal in 10 min"/"Height of the standing water needed for irrigation"`

`= 6000/0.08`

= 75000 m²

= 7.5 hectare    (As, 1 hectare = 10000 m²)

Hence, it will irrigate 7.5 hectare of area in 10 minutes.