Question

In a liquid, the force required to maintain the flow of layers is 5N, velocity gradient in du/dx, area of contact is 20m^2. Then what is the value of viscosity?

(a) 6.25 dz/du

(b) 0.15 dz/du

(c) 0.2 dz/du

(d) 0.25 dz/du

This question was addressed to me during an online exam.

I'd like to ask this question from States of Matter topic in portion States of Matter of Chemistry – Class 11

Answer 1

The correct choice is (d) 0.25 dz/du

To explain I would say: The formula of force required to maintain the flow of layers is given by the formula F = ηAdu/dz, where η is the coefficient of viscosity, A is the area of contact and du/dz is the velocity gradient. So by substituting we get an answer as  0.25dz/du.