JEE Main 2025 Jan 22 Shift 2, Physics Q18: Hydrodynamic

JEE Main2025Jan 22, Shift 2Physics

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

Solution

Equation of continuity for an incompressible fluid: $A_{1} v_{1} = A_{2} v_{2}$ .

With circular cross-sections of radii $R_{1} = 2 cm$ and $R_{2} = 1 cm$ :

$π R_{1}^{2} v_{1} = π R_{2}^{2} v_{2} \Rightarrow v_{2} = v_{1} (\frac{R _{1}}{R _{2}})^{2} = 2 \times (\frac{2}{1})^{2} = 2 \times 4 = 8 m/s$ .

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JEE Main 2025 Jan 22 Shift 2, Physics Q18: Hydrodynamic

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