Q 11-09-028JEE MainJEE Main 2026 (8 Apr, Shift 2)Medium
A liquid of density $600\ \text{kg/m}^3$ flowing steadily in a tube of varying cross-section. The cross-section at a point $A$ is $1.0\ \text{cm}^2$ and that at $B$ is $20\ \text{mm}^2$. Both the points $A$ and $B$ are in same horizontal plane, the speed of the liquid at $A$ is $10\ \text{cm/s}$. The difference in pressures at $A$ and $B$ points is ______ Pa.
Answer: (D) $72$
Concept. Continuity gives the speed at $B$; Bernoulli at one level gives the pressure difference.
Step 1. Speed at B. $v_B=0.1\times\dfrac{100}{20}=0.5$ m/s.
Step 2. Pressure difference. $\tfrac12(600)(0.25-0.01)=72$ Pa.
Answer. Option D.
Solution by Sreeraj P, M.Sc Physics
