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GATE 2026 AG – Question 35

Irrigation and Drainage Engineering · Wells and Pumps · 1 mark · Numerical answer

A centrifugal pump’s impeller speed increases by 30%. If its required power becomes n times the original power, find n, to two decimals.

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Correct answer: 2.10 to 2.30

Explanation

For the same pump and dynamically similar operating points, the affinity laws give $Q\propto N$, $H\propto N^2$ and $P\propto N^3$. The speed ratio is 1.30,so $P_2/P_1=1.30^3=2.197$. Thus **n=2.20**;the increase above the original is 119.7%.

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