A liquid of density 600 kg/m³ flowing…

Single correct+4 / -1Answer matches NTA’s final key

A liquid of density 600 kg/m³ flowing steadily in a tube of varying cross-section. The cross-section at a point $A$ is 1.0 cm² and that at $B$ is 20 mm². Both the points $A$ and $B$ are in same horizontal plane, the speed of the liquid at $A$ is 10 cm/s. The difference in pressures at $A$ and $B$ points is ______ Pa.

Solution

Continuity. $A_A = 1.0$ cm² $= 100$ mm², so $v_B = v_A\dfrac{A_A}{A_B} = 0.10 \times \dfrac{100}{20} = 0.50$ m/s.

Bernoulli (same height):

$P_A - P_B = \tfrac12\rho\left(v_B^2 - v_A^2\right) = \tfrac12 \times 600 \times (0.25 - 0.01) = 72 \text{ Pa}.$

Answer: 72 Pa.

Answer checked against the official answer key. The solution is our own working.

JEE MAIN 2026 · Properties of Solids and Liquids

Solution

Keep going