A water spray gun is attached to a hose of cross sectional area 30\ cm 2 . The gun comprises of 10 perforations each of cross sectional area of 15\ mm 2 . If the water flows in the hose with the speed of 50\ cm/s , calculate the speed at which the water flows out from each perforation. (Neglect any edge effects)

Physics · Fluid Mechanics

JEE Main 2026 — 4 April, Evening Shift — Question 7

A water spray gun is attached to a hose of cross sectional area $30\ \mathrm{cm}^2$ . The gun comprises of 10 perforations each of cross sectional area of $15\ \mathrm{mm}^2$ . If the water flows in the hose with the speed of $50\ \mathrm{cm/s}$ , calculate the speed at which the water flows out from each perforation. (Neglect any edge effects)

Option A:
$100\ \mathrm{m/s}$
Option B:
$10\ \mathrm{m/s}$
Correct
Option C:
$1000\ \mathrm{m/s}$
Option D:
$15\times10^2\ \mathrm{m/s}$

Answer: B

Step-by-step solution

Continuity equation: $A_{\text{hose}} V_{\text{hose}} = 10 \cdot a_{\text{perf}} \cdot v$ . $A=30\ \text{cm}^2$ , $V=50\ \text{cm/s}$ , $a=15\ \text{mm}^2 = 0.15\ \text{cm}^2$ . Thus $v = \frac{30\times50}{10\times0.15}=1000\ \text{cm/s}=10\ \text{m/s}$ .

Answer key and solution verified before publishing.

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Exam: JEE Main 2026
Paper: 4 April, Evening Shift
Subject: Physics
Chapter: Fluid Mechanics
Topic: Types of flow and Equation of Continuity