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Question
Water in a canal, 6 m wide and 1.5 m deep, is flowing at a speed of 4 km/h. How much area will it irrigate in 10 minutes, if 8 cm of standing water is needed for irrigation?
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Solution
Given:-
Speed of flowing water = 4km/h = 200/3 metres per minute
Width of canal = 6 m and height of canal = 1.5 m
Standing water requirement for irrigation = 8 cm = 0.08 m
Cross section area of canal = width of canal x height of canal = (6 * 1.5) m2
Volume of water needed to irrigate in 10 min = 10 x 6 x 1.5 x 200/3 = 6000m3
Volume of water irrigated = base area (of irrigated land) x height
= base area x 0.08m
6000 = base area x 0.08
Base area = 6000/0.08 =75000 m2
= 7.5 hectare [1 hectare = 10000 m2]
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