Water flows through a horizontal tube as shown in the figure. The difference in height between the water columns in vertical tubes is 5 cm and the area of cross-sections at A and B are 6text cm^2 and 3text cm^2 respectively. The rate of flow will be ____ textcm^3/s. (take g = 10 textm/s^2)
Bernoulli's Principle diagram for Q29 - JEE Main 2026 Morning
The figure illustrates a Venturi meter setup with water flowing through a variable cross-section tube.

Solution & Explanation

### Related Formula A_1 V_1 = A_2 V_2 P_1 + frac12rho V_1^2 = P_2 + frac12rho V_2^2 P_1 - P_2 = rho g h ### Core Logic From the continuity equation between A and B: A_AV_A = A_BV_B implies 6V_A = 3V_B implies V_B = 2V_A Applying Bernoulli's equation between A and B for a horizontal pipe: P_A + frac12rho V_A^2 = P_B + frac12rho V_B^2 P_A - P_B = frac12rho(V_B^2 - V_A^2) Since the height difference is h = 5text cm = 0.05text m, the pressure difference is rho gh. rho g times 0.05 = frac12rho( (2V_A)^2 - V_A^2 ) g times 0.05 = frac12(3V_A^2) ### Step 1: Calculate Velocity and Volume Flow Rate Solving for V_A: V_A = sqrtfrac2 times 10 times 0.053 = sqrtfrac13 = frac1sqrt3text m/s V_A = frac100sqrt3text cm/s Volume flow rate Q = A_A V_A: Q = 6text cm^2 times frac100sqrt3text cm/s = frac600sqrt3 = 200sqrt3text cm^3text/s ### Pattern Recognition In a horizontal Venturi meter, substituting V_2 = V_1 (A_1/A_2) directly into rho g h = frac12rho (V_2^2 - V_1^2) is the standard path. Working in CGS vs MKS units requires careful tracking; convert V_A to cm/s before multiplying by A_A in cm². ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Mechanical Properties of Fluids

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