Question-31 An incompressible fluid flows steadily through a cylindrical pipe having radius R at point A and \frac{R}{3} at point B further along the direction of flow of liquid. If the velocity at point A is V then that at point B is
(A) \frac{V}{9}
(B) \frac{V}{3}
(C) 3V
(D) 9V
Answer : (D)
Explanation:
Using equation of continuity,
\pi (R)^2 \times V = \pi (R/3)^2 v_2∴ v_2 = \frac{9R^2 V}{R^2} = 9V