Question

water in acanal ,30dm and 12dm deep is flowing with a velocity of 20km per hour .how much area will it irigate in 30min .if 9cm of standing water is desired ?

Answer 1

Given that Width of a canal = 30dm.

                                              = 300cm.

Given that Depth of a canal = 12dm.

                                               = 120cm.

Given that the velocity of flow of water per hour = 20.

Then the velocity of flow of water in 30 minutes = 20 * 30/60

                                                                                 = 10km

                                                                                 = 1000000cm.


Then the volume of the water = 300 * 120 * 1000000

                                                   = 360000000000cm^3.


Given that the height of standing water is 9cm.

We know that volume = area * height

         360000000000 = A * 9

           A = 360000000000/9

               = 4000000000.cm^2

               = 0.4km^2.


Therefore the area irrigated by this water if 9cm of standing water is desired = 0.4km^2.



Hope this helps!