Question

A square plate of 0.1 m side moves parallel to a second plate with a velocity of 0.1 m/s, both plates being immersed in water. If the viscous force is 0.002 N and the coefficient of viscosity is 0.01 poise, distance between the plates in m is

• A. 0.1
• B. 0.05
• C. 0.005
• D. 0.0005

Answer 1

Answer: (D)

0.0005

Answer 2

$\eta = 0.01$ Poise $= 0.001$ decapoise

(M.K.S. unit), dv = 0.1 m/s and F = 0.002 N

$F = \eta A \frac { d v } { d x }$

$\therefore d x = \frac { \eta A d v } { F } = \frac { 0.001 \times 0.01 \times 0.1 } { 0.002 } = 0.0005 \mathrm {~m}$.