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GATE 2022 ES – Question 58

Water Resources and Environmental Hydraulics · Environmental Hydraulics · 2 marks · Numerical answer

A water venturimeter and mercury differential manometer are shown. Mercury SG13.6,water specific weight9810 N/m³. Find p_Q−p_P in Pa, to one decimal.

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Correct answer: 7160.0 to 7163.0

Explanation

Q is .10 m below P; mercury interfaces differ .05 m. A pressure balance gives $p_Q-p_P=\gamma_w(.10)+(\gamma_{Hg}-\gamma_w)(.05)$. Thus $9810[.10+(13.6-1)(.05)]=\mathbf{7161.3}$ Pa. The .08 m connecting-water segment cancels; using13.6 instead of 12.6 for the differential head would count water twice.

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