# Hydraulics and Fluid Mechanics MCQ Questions & Answers

Hydraulics and Fluid Mechanics MCQs : This section focuses on the "Hydraulics and Fluid Mechanics". These Multiple Choice Questions (MCQs) should be practiced to improve the Hydraulics and Fluid Mechanics skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

A vertical wall is subjected to a pressure due to one kind of liquid, on one of its sides. The total pressure on the wall per unit length is (where w = Specific weight of liquid, and H = Height of liquid)

A. wH
B. wH/2
C. wH2/2
D. wH2/3

Question 2

Coefficient of contraction is the ratio of

A. actual velocity of jet at vena contracta to the theoretical velocity
B. loss of head in the orifice to the head of water available at the exit of the orifice
C. actual discharge through an orifice to the theoretical discharge
D. area of jet at vena contracta to the area of orifice

Question 3

The loss of head due to friction in a pipe of uniform diameter in which a viscous flow is taking place, is (where RN = Reynold number)

A. 1/RN
B. 4/RN
C. 16/RN
D. 64/RN

Question 4

The discharge over a rectangular notch is (where b = Width of notch, and H = Height of liquid, above the sill of the notch)

A. Cd x b2gH
B. Cd x b2g x H
C. Cd x b2g x H3/2
D. Cd x b2g x H2

Question 5

One litre of water occupies a volume of

A. 100 cm3
B. 250 cm3
C. 500 cm3
D. 1000 cm3

Question 6

The centre of buoyancy is the centre of area of the immersed body.

A. Correct
B. Incorrect

Question 7

The loss of head due to an obstruction in a pipe is twice the loss of head at its entrance.

A. Agree
B. Disagree

Question 8

Coefficient of resistance is the ratio of

A. actual velocity of jet at vena contracta to the theoretical velocity
B. area of jet at vena contracta to the area of orifice
C. loss of head in the orifice to the head of water available at the exit of the orifice
D. actual discharge through an orifice to the dieoretical discharge

Question 9

In a depressed nappe

A. the pressure below the nappe is atmospheric
B. the pressure below the nappe is negative
C. the pressure above the nappe is atmospheric
D. the pressure above the nappe is negative

Question 10

The discharge through a large rectangular orifice is given by (where H1 = Height of the liquid above the top of the orifice, H2 = Height of the liquid above the bottom of the orifice, b = Breadth of the orifice, and Cd = Coefficient of discharge)

A. Q = Cd x b2g(H2 - H1)
B. Q = Cd x b2g(H21/2 - H11/2)
C. Q = Cd x b2g(H23/2 - H13/2)
D. Q = Cd x b2g(H22 - H12)

Question 11

The kinematic viscosity is the

A. ratio of absolute viscosity to the density of the liquid
B. ratio of density of the liquid to the absolute viscosity
C. product of absolute viscosity and density of the liquid
D. product of absolute viscosity and mass of the liquid

Question 12

The weight per unit volume of a liquid at a standard temperature and pressure is called

A. specific weight
B. mass density
C. specific gravity
D. none of these

Question 13

The stability of a dam is checked for

A. tension at the base
B. overturning of the wall or dam
C. sliding of the wall or dam
D. all of these

Question 14

In order to measure the flow with a venturimeter, it is installed in

A. horizontal line
B. inclined line with flow upwards
C. inclined line with flow downwards
D. any direction and in any location

Question 15

The coefficient of viscosity may be determined by

A. capillary tube method
B. orifice type viscometer
C. rotating cylinder method
D. all of these

Question 16

If a body floating in a liquid returns back to its original position, when given a small angular displacement, the body is said to be in

A. neutral equilibrium
B. stable equilibrium
C. unstable equilibrium
D. none of these

Question 17

In open channels, the specific energy is the

A. total energy per unit discharge
B. total energy measured with respect to the datum passing through the bottom of the channel
C. total energy measured above the horizontal datum
D. kinetic energy plotted above the free surface of water

Question 18

The value of bulk modulus of a fluid is required to determine

A. Reynold's number
B. Froude's number
C. Mach number
D. Euler's number

Question 19

An ideal fluid is frictionless and incompressible.

A. Correct
B. Incorrect

Question 20

According to equation of continuity,

A. w1a1 = w2a2
B. w1v1 = w2v2
C. a1v1 = a2v2
D. a1/v1 = a2/v2

Question 21

Which of the following is an example of laminar flow?

A. Under ground flow
B. Flow past tiny bodies
C. Flow of oil in measuring instruments
D. all of these

Question 22

The power transmitted through a pipe is (where w = Specific weight in N/m3, and Q = Discharge in m3/s)

A. w x Q x H
B. w x Q x hf
C. w x Q (H - hf)
D. w x Q (H + hf)

Question 23

The body will sink down if the force of buoyancy is __________ the weight of the liquid displaced.

A. equal to
B. less than
C. more than

Question 24

A siphon is used to connect two reservoirs at different levels intervened by a high ridge.

A. TRUE
B. FALSE

Question 25

The discharge through a siphon spillway is

A. Cd x a2gH
B. Cd x a2g x H3/2
C. Cd x a2g x H2
D. Cd x a2g x H5/2

Question 26

A structure whose width is __________ the width of the channel, is called a flumed structure.

A. less than
B. more than

Question 27

The pressure measured with the help of a piezometer tube is in

A. N/mm2
B. N/m2
D. all of these

Question 28

In a free nappe,

A. the pressure below the nappe is atmospheric
B. the pressure below the nappe is negative
C. the pressure above the nappe is atmospheric
D. the pressure above the nappe is negative

Question 29

The coefficient of discharge for an external mouthpiece is

A. 0.375
B. 0.5
C. 0.707
D. 0.855

Question 30

The discharge over a right angled notch is (where H = Height of liquid above the apex of notch)

A. Cd 2g x H
B. Cd 2g x H3/2
C. Cd 2g x H2
D. Cd 2g x H5/2

Question 31

A weir is said to be broad crested weir, if the width of the crest of the weir is __________ half the height of water above the weir crest.

A. equal to.
B. less than
C. more than

Question 32

In a venturimeter, the velocity of liquid at throat is __________ than at inlet.

A. higher
B. lower

Question 33

In one dimensional flow, the flow

B. takes place in straight line
C. takes place in curve
D. takes place in one direction

Question 34

The Bernoulli's equation is based on the assumption that

A. there is no loss of energy of the liquid flowing
B. the velocity of flow is uniform across any cross-section of the pipe
C. no force except gravity acts on the fluid
D. all of the above

Question 35

The metacentric heights of two floating bodies A and B are 1 m and 1.5 m respectively. Select the correct statement.

A. The bodies A and B have equal stability
B. The body A is more stable than body B
C. The body B is more stable than body A
D. The bodies A and B are unstable

Question 36

A flow in which the volume of a fluid and its density does not change during the flow is called __________ flow.

A. incompressible
B. compressible

Question 37

The maximum efficiency of transmission through a pipe is

A. 50%
B. 56.70%
C. 66.67%
D. 76.66%

Question 38

The total energy line lies over the hydraulic gradient line by an amount equal to the

Question 39

When a tube of smaller diameter is dipped in water, the water rises in the tube due to viscosity of water.

A. TRUE
B. FALSE

Question 40

In an external mouthpiece, the absolute pressure head at vena contracta is __________ the atmospheric pressure head by an amount equal to 0.89 times the height of the liquid, above the vena contracta.

A. less than
B. more than

Question 41

An error of 1% in measuring head over the apex of the notch (H) will produce an error of __________ in discharge over a triangular notch.

A. 1%
B. 1.50%
C. 2%
D. 2.50%

Question 42

A manometer is used to measure

A. low pressure
B. moderate pressure
C. high pressure
D. atomospheric pressure

Question 43

The centre of gravity of the volume of the liquid displaced is called

A. centre of pressure
B. centre of buoyancy
C. metacentre
D. none of these

Question 44

The maximum discharge over a broad crested weir is

A. 0.384 Cd x L x H1/2
B. 0.384 Cd x L x H3/2
C. 1.71 Cd x L x H1/2
D. 1.71 Cd x L x H3/2

Question 45

The pressure less than atmospheric pressure is known as

A. suction pressure
B. vacuum pressure
C. negative gauge pressure
D. all of these