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

The correct option is A 4 : 49

Critical velocity $v=N_R\frac{\eta }{\rho r}\Rightarrow \frac{v_1}{v_2}=\frac{{\eta }_1}{{\eta }_2}\times \frac{{\rho }_2}{{\rho }_1}=\frac{52}{49}\times \frac{1}{13}=\frac{4}{49}$.