Two parallel plates, one moving at 4 m/s and the other fixed, are separated by a 5-mm-thick layer of oil of specific gravity0.80 and kinematic viscosity 125 E4 mzls. What is the average shear stress in the oil? (a) 80 Pa, (b) 100 Pa, (C) 125 Pa, (d) 160 Pa, (9) 200 Pa

option (a) 80 Pa

Explanation:

Data provided in the question:

v = 4 m/s

Distance between the plates, t = 5 mm = 5 * 10⁻³ m

Specific gravity, s = 0.80

Kinematic viscosity, ν = 1.25 * 10⁻⁴ m²/s

Now,

μ = sν

= 0.80 * 1.25 * 10⁻⁴

= 0.1 kg/m. s

average shear stress, τ = μ * [ v : t]

= 0.1 * [ 4 : 5 * 10⁻³ ]

= 80 Pa

Hence,

option (a) 80 Pa