Question

Water in a canal $,6m$ wide and $1.5m$ deep , is flowing with a speed of $10km/h$ . how much area will it irrigate in $30$ minute, if 8cm of standing water is needed.

Answer 1

Speed of flowing of water from canal is $10km/h$ , means length of water flows in $1$ hour $=5km$ , so length of water flows in $30$ minutes $=5km$

Now, volume of water flowing from canal $=$ length of water flows in $30$ minutes $\times$breadth of canal $\times$ deep of canal

$=5000m\times 6m\times 1.5m=45000m³$

Let area of field $=xm²$

Then, volume of water irrigates into the field $=$ area of field $\times$ height of water during irrigation

$=xm²\times 8\times 10⁻²m=0.08xm³$

Now, volume of water flowing from canal = volume of water in field

$45000m³=0.08xm³$

$x=562500m²$

We know, $1hectare=10000m²$

So, area of field in hectare $=562500/10000=56.25hectares$

Hence, this is the answer.