Correct Answer - Option 3 : 0.0775 N
Option(3)
CONCEPT:
-
Viscosity is the property of fluid by virtue of which an internal force of friction comes into play when a fluid is in motion and which opposes the relative motion between its different layers.
- The coefficient of viscosity of liquids is analogous to the Modulus of rigidity of solids
EXPLANATION:
-
Newton's formula for the viscous force between two parallel layers is given by
\(F =η A \frac {dv}{dx}\)
Here A = 25 cm2 = 25 × 10-4 m2 ,dx = 1 mm =10-3 m , η =1.55 Nsm-2 ,dv =2 × 10-2 ms-1
On putting the value of the above we get
\(F =η A \frac {dv}{dx}\) = 1.55 × 25 × 10-4 × 2 × 10-2 / 1 × 10-3 = 0.0775 N
The horizontal force required to move the plate with the speed of 2 cms-1 is 0.0775 N
- The coefficient of viscosity of a fluid can be defined as the ratio of shearing stress to the strain rate.
Coefficient of Viscosity.
η =\(\frac{F/A}{v/x}\) where v/x is dx.x/t ( velocity = dx/dt)=\(\frac{ Shearing stress}{Shear Strain/t} \)
-
Shearing Stress is the internal restoring force set up per unit area of cross-section of the deformed body is called stress.
-
Shearing Strain the ratio of change in length to the original length.