Question

Water in a canal, 5.4 m wide and 1.8 m deep, is flowing with a speed of 25 km/hr. How much area can it irrigate in 40 minutes, if 10 cm of standing water is required for irrigation?

Answer 1

Breadth , b = 5.4 m

Height[depth] , h = 1.8 m

Speed of canal = $\frac{25km}{hr}$

Length of canal in 1 hour = 25 km


Length of canal in 60 minutes = 25 km [ 1 hr = 60 min ]

Length of canal in $1min=\frac{25}{60}$

Length of canal in 40 min = $\frac{25}{60}\times 40$
= $16.67km$ [ approx . ]

= 16670 m


Volume of canal = $ltimesbtimesh$ .

= $16670\times 5.4\times 1.8m$
= $162032.4metres$

Height of standing water = 10 cm = 0.1 metres


Volume of water in canal = Volume of area irrigated

Volume of area irrigated = Area irrigated × height

162032.4 metres = Area irrigated × 0.1
Area irrigated = $\frac{162032.4}{0.1}$

= $1620324m^2$

$1m^2$ = 0.0001 hectares

Area irrigated = 162.0324 hectares