15. 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-d
(2)