Question

Water in a canal,5.4m wide and1.8m deep,is flowing with a speed of 25km/he. How much area can it irrigate in 40 min,if 10cm of standing water is required for irrigategation

Answer 1

b= 5.4 m
h=1.8m

v= 25 km/h
therefore, l=25km per hour
therefore water that would be flowing in 40 minutes=40*25/60=50/3km=50000/3m

area of irrigation= area water flowing in 40minutes
volume of water which irrigates the land= volume water flowing from canal in 40 minutes

and 10 cm or 1/10 m of standing water is required for irrigation
therefore,
l*b*h=L*B*H
l*b*1/10=50000/3*5.4*1.8
l*b=300000*5.4
l*b=16200000sq. m
therefore, area to be irrigated when 10 cm of standing water is required=16200000sq. m

Answer 2

given ,
speed of flowing water= 25 km/hr= 25000/60=2500/6=1250/3 m/min
amount of water coming out in 1 minute= 5.4×1.8×1250/3= 40500m^3
then amount of water coming out in 40min = 40500×4=162000 m^3
area that it can irritgate if 10 cm of standing water is required
=162000×100/10=1620000 m^2