Question

The space between two parallel horizontal plates kept 6 mm apart is filled with 

crude oil of dynamic viscosity 2.5 kg/ms. If the lower plate is stationary and upper plate 

is pulled with a velocity of 1.25 m/s. determine the shear stress on the lower plate.

Answer 1

To find:

$\tau$ (Shear stress in the oil)

$du/dy=v/h=constant$

$1.25/0.004=312.5/s$

$\tau$ =$2.5\times312.5=781.25N/m^2$

Thus the Shear stress between the oil layers is $781.25N/m^2$