Concepts Of Physics MCQ Edition [Volume 1]PhysicsFluid Mechanics
Water flows through two identical tubes A and B . In a specified time interval, a volume V₀ of water passes through tube A while 2V₀ passes through tube B . Which of the following statements may be correct?
Options
- AThe flow is turbulent in both the tubes.
- BThe flow is steady in B but turbulent in A .
- CThe flow is steady in both the tubes.
- DThe flow is steady in A but turbulent in B .
Correct answer
D. The flow is steady in A but turbulent in B .
Step-by-step solution
Let the cross-sectional area of the identical tubes be A and the specified time interval be t . The volume flow rate in tube A is Q_A = V₀ t = A v_A , where v_A is the velocity of water in tube A . The volume flow rate in tube B is Q_B = 2V₀ t = A v_B , where v_B is the velocity of water in tube B . From the above equations, we get v_B = 2v_A . The nature of the flow is determined by the Reynolds number, R_e = v D . Since the tubes and the fluid are identical, R_e v . Therefore, R_ e,B = 2R_ e,A . For steady (strea