Q 11-09-016NEETJEE MainEasy
Water flows through a horizontal pipe whose diameter narrows from $4$ cm to $2$ cm. If the speed in the wide part is $1$ m s$^{-1}$, the speed in the narrow part is
Answer: (C) $4$ m s$^{-1}$
Concept. Continuity: $A_1v_1 = A_2v_2$ with $A \propto d^2$.
Step 1. Speed. $v_2 = 1 \times \left(\dfrac42\right)^2 = 4$ m/s.
Answer. $4$ m s$^{-1}$ (Option C).
Solution by Sreeraj P, M.Sc Physics