Question

For flow of water in tube, the velocity at surface is ___________

(a) zero

(b) equal to velocity at 1/3 of diameter

(c) equal to velocity at 1/2 of diameter

(d) equal to velocity at centre

The question was asked in final exam.

I need to ask this question from Poiseuille’s Law in division Permeability of Geotechnical Engineering I

Answer 1

Right option is (a) zero

Explanation: The surface of the tube is wet forming a very thin layer of water that is immobile due to molecular attraction. So the velocity at the surface is zero.