Water in a canal 30 dm wide and 12 dm deep, is flowing with a velocity of 100 km every hour. What much area will it irrigate in 30 minutes if 8 cm of standing water is desired?
Given that,
Water in the canal forms a cuboid of Width (b) = 30 dm = 3 m
Height (h) = 12 dm = 1.2 m
Cuboid length is equal to the distance traveled in 30 min with the speed of 100 km per hour.
Therefore, Length of the cuboid = 100∗30/60 = 60 km = 50000 metres
So, volume of water to be used for irrigation $=5000 * 3 * 1.2 \mathrm{~m}^{3}$
Water accumulated in the field forms a cuboid of base area equal to the area of the field and height equal to 8/100 metres
Therefore, Area of field∗8/100 = 50000 ∗ 3 ∗ 1.2
$\Rightarrow$ Area of field $=\frac{50000 * 3 * 1.2 * 100}{8}$
⇒ 22, 50, 000 metres.
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