CBSE Class 10 Answered

We assume that the depth is measured along the dimension which is 0.8 m side of the rectangular pipe.

Since the depth is 0.3 m, the water flow cross section is 0.3 x 1.2 = 0.36 m²,

while the pipe cross section is 0.8 x 1.2 = 0.96 m².

Volume flow rate = Flow Cross section x velocity = 0.36 m² x 3 m/min = 1.08 m³/min = 1.08 x 60 = 64.8 m³/hr

64.8 cubic meters of water flow in one hour.

Again the water flow cross section is 0.8 x 1.2 = 0.96 m².

Volume flow rate = Flow Cross section x velocity = 0.96 m² x 15 m/min =  14.4 m³/min = 14.4 x 60 = 864 m³/hr

Hence percentage increase = (864 - 64.8) x 100/64.8 = 1233 %

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Team,

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