# Fluid Mechanics MCQ (Multiple Choice Questions) - SchoolingAxis

1. The wake

a) always occurs before a separation point

b) always occurs after a separation point

c) is a region of high pressure intensity

d) none of the above

Ans: b

2. The maximum thickness of boundary layer in a pipe of radius r is

a) 0

b) r/2

c) r

d) 2r

Ans: c

3. The hydraulic grade line is

a) always above the centre line of pipe

b) never above the energy grade line

c) always sloping downward in the direction of flow

d) all of the above

Ans: b

4. Two pipe systems are said to be equivalent when

a) head loss and discharge are same in two systems

b) length of pipe and discharge are same in two systems

c) friction factor and length are same in two systems

d) length and diameter are same in two systems

Ans: a

5. In series-pipe problems

a) the head loss is same through each pipe

b) the discharge is same through each pipe

c) a trial solution is not necessary

d) the discharge through each pipe is added to obtain total discharge

Ans: b

6. Select the correct statement.

a) The absolute roughness of a pipe de-creases with time.

b) A pipe becomes smooth after using for long time.

c) The friction factor decreases with time.

d) The absolute roughness increases with time.

Ans: d

7. A valve is suddenly closed in a water main in wl.ich the velocity is 1 m/sec and velocity of pressure wave is 981 m/ sec. The inertia head at the valve will be

a) 1 m

b) 10m

c) 100m

d) none of the above

Ans: c

8. The speed of a pressure wave through a pipe depends upon

a) the length of pipe

b) the viscosity of fluid

c) the bulk modulus for the fluid

d) the original head

Ans: c

9. When time of closure tc = L/v0 (where L is length of pipe and v0 is speed of pressure wave), the portion of pipe length subjected to maximum head is

a) L/4

b) L/3

c) L/2

d) L

Ans: a

10. If the elevation of hydraulic grade line at the junction of three pipes is above the elevation of reservoirs B and C and below reservoir A, then the direction of flow will be

a) from reservoir A to reservoirs B and C

b) from reservoir B to reservoirs C and A

c) from reservoir C to reservoirs A and B

d) unpredictable

Ans: c