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 mins, if 10 cm of standing water is required for irrigation?

Answer 1

Given that

Breadth ( b ) = 5.4 m
Height ( h )= 1.8 m or depth. 

Speed of water in canal = 25 km/hr

Which means,

Length of canal in 60 minutes = 25 km        ( Because 1 hr = 60 min )

Length of canal in 1 min =  25/60

Length of canal in 40 min = 25/60 × 40     
                                    = 16.67 km (approx.)     or,                                         
                                    = 16670 m


We know that volume of canal =  l *b *h 
                           = 16670  × 5.4  × 1.8 m                                                     
                         = 162032.4 metres

Height of standing water = 10 cm or 0.1 metres

Now,
Volume of water in canal = Volume of area irrigated

Volume of area irrigated = Area irrigated × height
162032.4 m = Area irrigated × 0.1

Area irrigated =   162032.4 / 0.1
                       =  1620324 m²

Answer 2

I hope it will be helpful for you......