Water in a canal, `30\ d m\ w i d e\ a n d\ 12 d m\ d e e p ,\ ` is flowing with a velocity of `20 k m\ p e r\ hou rdot` How many area will it irrigate in 30min, if `9\ c m` of standing water is desired?

Explanation

Answer:
Velocity of water`=20(Km)/(h)`

Water in the canal forms a cuboid of breadth `= 12dm= 12/10 m=1.2m`

Height `= 30dm=
30/10m=3m`
Length `=` Distance covered by water in `30` minutes
`= `Velocity of water xx time
`=20000 xx
30/60=10000 m`
Therefore,
Volume of water flown in 30 min = lbh`=(1.2xx3xx10000)=36000 m^3`
Suppose area irrigated be `A m^2`. Then,
`A xx 9/100=` Volume flown in `30` minutes
`A xx (9)/(100)=36000`
`A=400000 m^2`
Hence, area irrigated `=400000 m^2 `