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GATE 2022 MT – Question 35

Transport Phenomena and Rate Processes · Fluid flow and momentum transfer · 1 mark · Numerical answer

A Newtonian incompressible liquid lies between parallel plates separated by $10^{-3}$ m, as shown. A shear stress of 5 Pa maintains upper-plate speed 2 m/s relative to the lower plate. The viscosity is ______ $\times10^{-3}$ Pa·s (one decimal place).

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Correct answer: 2.5 to 2.5

Explanation

Newton’s viscosity law is $\tau=\mu\,du/dy$. The gradient is $2/0.001=2000$ s$^{-1}$, so $\mu=5/2000=0.0025$ Pa·s. The requested coefficient is **2.5**.