Question

Water in a canal, 30dm wide and 12dm deep is flowing with velocity of 10km/hr. How much area will it irrigate in 30 minutes, if 8cm of standing water is required for irrigation?

Answer 1

Hint: We have given here the width and depth of the canal and we have to calculate the area irrigated w.r.t the time given.

Complete step-by-step answer:
We have,
Width of the canal = 30dm= 300cm = 3m
Depth of the canal = 12dm = 120cm = 1.2m
It is given that the water is flowing with a velocity 10km/hr = 10000m/h
Therefore length of the water column formed in 30mins =$10000 \times \dfrac{1}{2}$ = 5000m
Volume of the canal is given by the formula, Volume=$Length \times Width \times Depth$
Let $x{m^2}$ of area is irrigated in
$x \times \dfrac{8}{{100}} = 5000 \times 1.2 \times 3$
$ \Rightarrow x = 225000{m^2}$
So the answer is $225000{m^2}$.

Note: To solve such questions we have to first convert dm to m and then find water flowing in the canal irrigated w.r.t to speed and time and then find the area irrigated by the water.