Hydraulics and Fluid Mechanics – Section 2

1. A compound pipe of diameter d1d2 and d3 having lengths l1l2 and l3 is to be replaced by an equivalent pipe of uniform diameter d and of the same length (l) as that of the compound pipe. The size of the equivalent pipe is given by 2. The velocity corresponding to Reynold number of 2800, is called

A. sub-sonic velocity
B. super-sonic velocity
C. lower critical velocity
D. higher critical velocity

Correct Answer: D. higher critical velocity

3. When the pipes are in series, the total head loss is equal to the sum of the head loss in each pipe.

A. Yes
B. No

4. Whenever a plate is held immersed at some angle with the direction of flow of the liquid, it is subjected to some pressure. The component of this pressure, at right angles to the direction of flow of the liquid is known as lift.

A. True
B. False

5. The efficiency of power transmission through the pipe is (where H = Total supply head, and hf = Head lost due to friction in the pipe) 6. The discharge over a rectangular weir, considering the velocity of approach, is (where H1 = Total height of water above the weir = H + Ha , H = Height of water, over the crest of the weir, and Ha = Height of water, due to the velocity of approach) 7. A flow in which __________ force is dominating over the viscosity is called turbulent flow.

A. elastic
B. surface tension
C. viscous
D. inertia

8. If an incompressible liquid is continuously flowing through a pipe, the quantity of liquid passing per second is different at different sections.

A. True
B. False

9. The atmospheric pressure at sea level is

A. 103 kN/m2
B. 10.3 m of water
C. 760 mm of mercury
D. all of these

Correct Answer: D. all of these

10. When the pressure intensity at a point is less than the local atmospheric pressure, then the difference of these two pressures is called vacuum pressure.

A. Agree
B. Disagree