RE-NEET 2026 Physics Flow of Fluids MCQ Question

To find the rate of flow of water through the pipe, we can use the principle of continuity, which states that the mass flow rate must remain constant in a streamline flow. The equation is given by:

$A_1 v_1 = A_2 v_2$

where $A_1$ and $A_2$ are the cross-sectional areas at points P and Q, and $v_1$ and $v_2$ are the flow velocities at those points.

Given:

• $A_P = 40 \, \text{cm}^2 = 0.004 \, \text{m}^2$
• $A_Q = 20 \, \text{cm}^2 = 0.002 \, \text{m}^2$

Using Bernoulli's equation and the pressure difference, we can derive the velocities. The flow rate $Q$ is given by:

$Q = A v$

Calculating $Q$ at point P:

$Q = A_P v_P = A_Q v_Q$

Substituting the areas and solving gives:

$Q = 400 \, \text{cm}^3/\text{s}$

Thus, the correct answer is C. The other options fail because they do not satisfy the continuity equation given the specified areas and pressure difference.