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Suppose a dam is 250 m wide and the water is 40 m deep at the dam. What is(i) the average pressure on the dam (ii) the force exerted against the dam due to the water? |
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Answer» Data : Width, L = 250 m, depth H = 40 m, ρ = 1000 kg/m3 , g = 9.8 m/s2 Since pressure increases linearly with depth, the average pressure pav due to the weight of the water is the pressure at the average depth h of 20 m. The force exerted on the dam by the water is the average pressure times the area of contact, F = pav A = pav LH. (i) pav = hρg = (20)(1000)(9.8) = 1.96 × 105Pa (ii) F = pavA = pavLH = (1.96 × 105)(250)(40) = 1.96 × 105N |
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