In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of___________________?

Related Mcqs:

1. Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will_______________?

   A. Increase
   B. Decrease
   C. Remain unchanged
   D. Increase or decrease depending on the pipe material

2. Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement ?

   A. f1 = f2
   B. f1 < f2
   C. f1 > f2
   D. Data not sufficient to relate f1 & f2

3. For a given Reynolds number, in a hydraulically smooth pipe, further smoothening ____________ the friction factor?

   A. Brings about no further reduction of
   B. Increases
   C. Decreases
   D. None of these

4. Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined) ?

   A. ε = ε0 + α.t
   B. ε = ε0 + α.t2
   C. ε = ε0 + α.t3
   D. ε = ε0 + α.t4

5. In turbulent flow, a rough pipe has the same friction factor as a smooth pipe____________________?

   A. In the zone of complete turbulence
   B. When the roughness projections are much smaller than the thickness of the laminar film
   C. Everywhere in the transition zone
   D. When the friction factor is independent of the Reynold’s number

6. A pipe is defined as ‘hydraulically smooth’, if the friction factor_________________?

   A. Is not a function of Reynolds number
   B. For a given Reynolds number remains constant even on further smoothening of the pipe
   C. Is zero irrespective of the Reynolds number
   D. None of these

7. Transition length for turbulent flow in smooth pipe is equal to _____________ times the pipe diameter?

   A. 0.5
   B. 5
   C. 50
   D. 500

8. The friction factor for turbulent flow in a hydraulically smooth pipe______________?

   A. Depends only on Reynolds number
   B. Does not depend on Reynolds number
   C. Depends on the roughness
   D. None of these

9. A pipe of I.D. 4 m is bifurcated into two pipes of I.D. 2 m each. If the average velocity of water flowing through the main pipe is 5 m/sec, the average velocity through the bifurcated pipes is__________________?

   A. 20 m/sec
   B. 10 m/sec
   C. 5 √2 m/sec
   D. 5 m/sec

10. The pressure drop per unit length of pipe incurred by a fluid ‘X’ flowing through pipe is Δp. If another fluid ‘Y’ having both the specific gravity & density just double of that of fluid ‘X’, flows through the same pipe at the same flow rate/average velocity, then the pressure drop in this case will be__________________?

    A. Δp
    B. 2Δp
    C. Δp2
    D. Δp/2