Monday, February 8, 2010

Mechanical Engineering Board Exam Question: Fluid Mechanics

Below are set of questions taken from a Mechanical Engineering handbook under the topic fluid mechanics.

Choose the BEST answer.

1. In fluid mechanics, it is the ratio of the area of the vena contracta to the area of the smaller pipe.
a. Contraction coefficient
b. Friction coefficient
c. Expansion coefficient
d. Reynolds’ Number

2. When the Reynolds number of a fluid flow is 3500, the flow is…
a. Laminar
b. Turbulent
c. Intermediate between turbulent or laminar
d. There’s is no fluid flow due to very high viscosity

3. What will happen if the pressure of water flowing in a pipe dropped below its vapor pressure?
a. Water hammer will occur
b. Water will stop flowing
c. bubbles will form inside the pipe
d. Nothing will happen

4. It is the common name for the rattling noise heard inside the pipe as a result the instantaneous rise in the fluid pressure.
a. Cavitation
b. Eddies
c. Water hammer
d. Water strain

5. It is flow pattern where a fluid flows in concentric circles with no radial flow.
a. Doublet
b. Vortex
c. Parallel
d. Oblique

6. In an open channel flow (open channel refers to flows with free surface), what is the optimum channel shape for maximum flow rate?
a. Rectangular
b. Inverted triangle
c. Semi-circular
d. All of the above

7. Which factor(s) affects the flow regime (laminar or turbulent) of a fluid in a pipe?
a. Material of the pipe
b. Viscosity of the fluid
c. Density of the fluid
d. Both a and b
e. A B and C are all factors

8. The greatest contributor to the head losses in pipes is…
a. Fittings
b. Bends and corners
c. Length of pipe
d. Change in section

9. What will happen to the buoyant force if the density of the liquid is decreased?
a. increase
b. decrease
c. remain the same
d. increase then decrease

10. For a partially immersed body, the point at which the line of action of the buoyancy force cuts the vertical centre line of the floating body in the displaced position is known as the…
a. centroid
b. metacenter
c. center of pressure
d. epicenter

Answers will be posted after a couple of days.


  1. 1. What is kinematic viscosity ? How the fluids are classified ? On what factors
    does the viscosity depend ?
    2. Discuss the various types of flows in an open channel. (10)
    3. Show in detail the differences in discharges through a small rectangular orifice
    and a large rectangular orifice.
    4. Define compressibility. How is it related to bulk modulus of elasticity ? Define
    cohesion and adhesion.
    5. Explain the working of hydraulic accumulator with neat diagram. (10)

    6. A pipe diameter 300 mm and length 3500 m is used for the transmission of
    power by water. The total head at the inlet of the pipe is 500 m. Find the maximum
    power available at the outlet of the pipe if the value of f = 0.0006. (5)
    7. Water at the rate of 0.4 cumec flows through a 1m diameter vitrified sewer when
    the sewer pipe is half full. Find the slope of the water, if Manning s N is 0.0013. (10)

    8. Design a pelton wheel for the following data:
    Head of water = 150 m
    Power to be developed = 600 kw
    Speed of wheel = 360 rpm
    9. Write a short notes on force exerted by the Jet on a fixed vertical plate and on
    inclined plate.
    10. Derive the condition for most economical rectangular channel. (10)

    i) _______ is device used for lifting heavy weights by the application of a much
    smaller force.
    ii) The maximum efficiency of transmission through a pipe is ______
    iii) The time of emptying a tank over a triangular notch is _______
    iv) ______ is a mechanical device to increase the pressure energy of a fluid.
    v) Device used for measuring the rate of flow of a fluid flowing through a pipe is
    12. Multiple choice question. (Each question carries 2 marks)
    i) A double overhung pelton wheel has ____.
    a) Tow Jets b) Tow Runner
    c) Four Jets d) Four Runners
    ii) The _____ is a device used for raising or transferring _______ heavy loads.
    a) Hydraulic, Coupling b) Hydraulic, Torque Converter
    c) Hydraulic, Cranes d) None of above
    iii) The center of gravity of the volume of the liquid displaced by a floating body
    is ____ called.
    a) Center of pressure b) Center of buoyancy
    c) Metacenter d) All of these

    iv) A fluid which possesses viscosity is known as ________.
    a) Ideal b) Real
    c) Newtonian d) Non Newtonian
    v) Atmospheric pressure varies with ______.
    a) Altitude b) Temperature
    c) Weather condition d) None of these
    13. True o r false (Each question carries 1 mark)
    i) Bernoulli s theorem is based on law of conservation of energy.
    ii) Centre of buoyancy is centroid of fluid displaced.
    iii) A multistage pump is used to give high discharge.
    iv) The suction head is a horizontal distance of centerline of centrifugal pumpone
    below the water surface.
    v) Borda s mouth piece is an external mouth piece.

    1. Is this a board exam questions? Coz its trying to ask us to draw

  2. work shop process

    1. Describe the working principles of a drilling machine. (05)
    2. What are the properties of moulding sand, explain ? What is the composition of
    moulding sand ?
    3. What are ladels ? Describe the different type of ladels used for pouring the metal. (10)
    4. Draw the sketch of Lathe machine and explain the function of all parts. (10)
    5. Explain types of chip with neat sketch.
    Answer any three questions. (Question No. 6 is compulsory)
    6. What do you mean by Tool failure ? Explain wear on the flank of the tool. (05)
    7. Discuss the various types of High Speed Tool steels along with their utilities. (10)
    8. (a) Why large number of tooth in a milling cutter is used for rough cutting ?
    (b) Explain the causes and remedies of loading of a grinding wheel ? (10)
    9. How the welding is classified ? Explain them briefly. (10)
    10. What are the objectives of Metal finishing processes ? Explain with sketch processes
    of Honing.

    11. Fill in the blanks (Each question carries 2 marks)
    (i) The angle between lathe centers is ______________.
    (ii) Grinding wheel is a ________ cutting tool.
    (iii) The process of making cavity in the compact sand is called _____
    (iv) The ratio of pitch circle diameter to number of teeth is ______
    (v) _____ abusive is used for grinding materials of high tensile strength.
    12. Multiple choice question. (Each question carries 2 marks).
    (i) The flux commonly used in brazing is _______.
    (a) Zinc chloride (b) Ammonium chloride
    (c) Rosin plus alcohol (d) Borax
    (ii) Tool life is largely affected by ________.
    (a) Cutting speed (b) Tool geometry
    (c) Depth of cut (d) Feed
    (iii) A casting defect which result general enlargement of casting is called _____.
    (a) Shift (b) Sand wash
    (c) Swell (d) Blow holes
    (iv) Die casting dies are generally made of _______.
    (a) Cast iron (b) Aluminum alloy
    (c) Alloy steels (d) Bronze
    (v) Cold working of metal increases_________.
    (a) Tensile strength (b) Yield strength
    (c) Hardness (d) All of these
    13. True or false (Each question carries 1 mark)
    (i) The surface to be machine marked on the pattern by red colour.
    (ii) In a shaper the metal is removed at the return stroke.
    (iii) Drilling can be done on a lathe.
    (iv) Carburising flame is used to weld brass and bronze.
    (v) Wood pattern is more suitable than solid pattern.

    1. R dz questions from board exam