Question

Two horizontal plates are placed 14 mm apart and the space between them is filled with an oil of viscosity 1.4 N-s/m2. If the upper plate moves with 2.5 m/s, the shear stress in the oil is

Answer 1

Answer:

238

Explanation:

Dynamic viscosity of oil = 1.4 N-s/m²

Movement of upper plane = v = 2.5m/s

h = 14mm = 1.4cm

According to Newton’s law of viscosity -  

τ∝du/ dy (rate of strain)

Thus, τ = μ.du/dy

where, μ is the proportionality constant

Thus, du/dy = vh =constant

=2.5/1.44×10−2

= 170

∴τ = 1.4 × 170

= 238

Thus the Shear stress between the oil layers is 238N/m²