JEE Main · 2025 · 22 Jan 2025 · Shift 2 · Fluid Mechanics

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The tube of length L is shown in the figure. The radius of cross section at the point (1) is 2 cm and at the point (2) is 1 cm , respectively. If the velocity of water entering at point (1) is

2 m / s

, then velocity of water leaving the point (2) will be :

(A) $2 m / s$
(B) $4 m / s$
(C) $6 m / s$
(D) $8 m / s$ ✓ Correct

Answer: (D)

Solution

By the equation of continuity for an incompressible fluid,

A_{1} v_{1} = A_{2} v_{2}

A_{1} = π r_{1}^{2} = π (2)^{2} = 4 π cm^{2}, A_{2} = π r_{2}^{2} = π (1)^{2} = π cm^{2}

4 π (2) = π v_{2} \Rightarrow v_{2} = 8 m/s

JEE Main · 2025 · 22 Jan 2025 · Shift 2 · Single correct option

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