Types of Flow, Reynolds Number & Continuity question from JEE Main 2020 (7 Jan, Shift 2)

Answer: (b)

1. Continuity: $v \propto \dfrac{1}{A} \propto \dfrac{1}{d^2}$.
2. Minimum velocity is at maximum diameter: $\dfrac{v_{min}}{v_{max}} = \left(\dfrac{d_{min}}{d_{max}}\right)^2 = \left(\dfrac{4.8}{6.4}\right)^2$
3. $= \left(\dfrac{3}{4}\right)^2 = \dfrac{9}{16}$
4. So the answer is (b) $\dfrac{9}{16}$.