Question

Two different liquids are flowing in two tubes of equal radius. The ratio of coefficients of viscosity of liquids is 52:49 and the ratio of their densities is 13:1, then the ratio of their critical velocities will be

• A. 4 : 49
• B. 49 : 4
• C. 2 : 7
• D. 7 : 2

Answer 1

Answer: (A)

4 : 49

Answer 2

Critical velocity $v = N _ { R } \frac { \eta } { \rho r }$

⇒ $\frac { v _ { 1 } } { v _ { 2 } } = \frac { \eta _ { 1 } } { \eta _ { 2 } } \times \frac { \rho _ { 2 } } { \rho _ { 1 } } = \frac { 52 } { 49 } \times \frac { 1 } { 13 } = \frac { 4 } { 49 }$.