Question

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

Answer 1

Solution:

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Given:

Water in a canal is 5.4 m wide and 1.8m deep, is flowing with the constant speed of 25kmph.

l<----5.4m-->l
__________
l                     l    T
l                     l     l
l                     l  1.8m
l_________ l  _l_

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To find :

The area it can irrigate in 40 min, (10cm of standing water is required)

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The amount (volume) of water used for irrigation is,

The volume of standing water = volume of dimension x height of water level,

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First we should convert all the units to same,

1 kmph = 1000meter p(60 min)

25 kmph = 25000 p (60min)

In 40 min  it can fill,

25000 m = 60min,

60 x $\frac{2}{3}$ =40,.

so,

25000 x $\frac{2}{3}$ = 40,min

$\frac{50000}{3}$ m = 40 min

so, the volume of water level
(Dimensons:

l = $\frac{50000}{3}$m

b = 5.4 m

h = 10cm = 0.1m)

=> lbh cu.units

=> $( \frac{50000}{3} )( 5.4 )(1.8)$

=>(50000)(1.8)(1.8)

=>50000(3.24)

=>162000 m³

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We know that,

volume of water level = irrigated area x height of the water level required,.

162000 = x (0.1)

x = 162000($(0.1)^{-1}$)

x = 162000 (10)

x = 1620000m²

 ∴ The area of irrigated field is 1620000m²

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                                                      Hope it Helps !!