Question

The maximum velocity of a fluid in a tube for which the flow remains streamlined is called its:

• A. Terminal velocity
• B. Critical velocity
• C. Turbulent velocity
• D. Streamlined velocity
• E. Surface velocity

Hint:

Critical velocity depends on the fluid's density, viscosity, and the diameter of the tube.

Answer 1

The Correct Option is B

Critical velocity is the highest velocity a fluid can attain while still maintaining laminar (streamlined) flow. 
Beyond this speed, the flow becomes turbulent. \[ \text{Reynolds number} \, (Re) = \frac{\rho v d}{\eta} \] where \( v \) is the velocity of the fluid. If \( Re \) exceeds a critical value (typically around 2000 for pipe flow), turbulence occurs.