Question

Water in a canal, 6m wide and 1.5 m deep, is flowing with the speed of 10 Km/hr. How much area will it irrigate in 30 minutes, if 8cm of standing water is needed.

Answer 1

Let the canal be cuboidal
volume of water flowing to field per hour=
6×1.5×1000
=9000m^3
volume of field irrigated in 1/2 hour=(0.08*A)1/2

now ATQ
1/2 ( 0.08*A)=9000
A= 90000×2 ×100/8=22500cm^2

Answer 2

Given Width of the canal = 6m.

Given Depth of the canal = 1.5m.

Given that water is flowing at the speed of 10km/hr = 10000m/hr.

Thus, The length of water column formed in 30 minutes = 0.5 * 10000

                                                                                               = 5000 m.

Volume of the water flowing in 0.5 hours = 5000 * 6 * 1.5

                                                                     = 45000 m^3.


Given the area of water needed = 8cm.

Suppose Area irrigated in 0.5 hours be x.Then

45000 = x * 8cm

45000 = x * 8/100 m

45000 = 8x/100 m

x = 4500000/8

   = 562500 m^2.

Area irrigated in 0.5 hour = 562500m^2 (or) 56.25 hectares.


Hope this helps!