Unit-III : Fundamental of Mechanical Engineering MCQ
1. When a body is placed over a liquid, it will sink down if
(A) Gravitational force is equal to the upthrust of the liquid
(B) Gravitational force is less than the upthrust of the liquid
(C) Gravitational force is more than the up-thrust of the liquid
(D) None of the above
Answer: c
2. The property by virtue of which a liquid opposes relative motion between its different layers is called
(A) Surface tension
(B) Coefficient of viscosity
(C) Viscosity
(D) Osmosis
Answer: c
3. When a body floating in a liquid, is displaced slightly, it oscillates about
(A) (C)G. of body
(B) Center of pressure
(C) Center of buoyancy
(D) Metacentre
Answer: d
4. The pressure of the liquid flowing through the divergent portion of a Venturimeter
(A) Remains constant
(B) Increases
(C) Decreases
(D) Depends upon mass of liquid
Answer: c
5. In an immersed body, centre of pressure is
(A) At the centre of gravity
(B) Above the centre of gravity
(C) Below be centre of gravity
(D) Could be above or below e.g. depending on density of body and liquid
Answer: c
6. Steady flow occurs when
(A) The direction and magnitude of the velocity
at all points are identical
(B) The velocity of successive fluid particles, at any point, is the same at successive periods of time
(C) The magnitude and direction of the velocity do not change from point to point in the fluid
(D) The fluid particles move in plane or parallel planes and the streamline patterns are identical in each plane
Answer: b
7. fluid which obeys the Newton’s law of viscosity is termed as
(A) Real fluid
(B) Ideal fluid
(C) Newtonian fluid
(D) Non-Newtonian fluid
Answer: c
8. A one dimensional flow is one which
(A) Is uniform flow
(B) Is steady uniform flow
(C) Takes place in straight lines
(D) Involves zero transverse component of flow
Answer: d
9. Dimensions of surface tension are
(A) ML°T⁻²
(B) ML°T
(C) ML r²
(D) ML²T²
Answer: a
10. The property of fluid by virtue of which it offers resistance to shear is called
(A) Surface tension
(B) Adhesion
(C) Cohesion
(D) Viscosity
Answer: d
11. A fluid in equilibrium can’t sustain
(A) Tensile stress
(B) Compressive stress
(C) Shear stress
(D) Bending stress
Answer: c
12. Fluid is a substance that
(A) Cannot be subjected to shear forces
(B) Always expands until it fills any container
(C) Has the same shear stress at a point regardless of its motion
(D) Cannot remain at rest under action of any shear force
Answer: d
13. The unit of viscosity is
(A) Meters² per sec
(B) kg-sec/meter
(C) Newton-sec per meter²
(D) Newton-sec per meter
Answer: b
14. A pressure of 25 m of head of water is equal to
(A) 25 kN/ m²
(B) 245 kN/ m²
(C) 2500 kN/m²
(D) 2.5 kN/ m²
Answer: b
15. Dynamic viscosity of most of the gases with rise in temperature
(A) Increases
(B) Decreases
(C) Remain unaffected
(D) Unpredictable
Answer: a
16. Low specific speed of a pump implies it is
(A) Centrifugal pump
(B) Mixed flow pump
(C) Axial flow pump
(D) None of the above
Answer: a
17. Head developed by a centrifugal pump is
(A) Proportional to diameter of impeller
(B) Proportional to speed of impeller
(C) Proportional to diameter and speed of impeller
(D) None of the above
Answer: c
18. In centrifugal pumps, maximum efficiency is obtained when the blades are
(A) Straight
(B) Bent forward
(C) Bent backward
(D) Radial
Answer: c
19. A double overhung Pelton wheel has
(A) Two jets
(B) Two runners
(C) Four jets
(D) Four runners
Answer: b
20. Medium specific speed of a pump implies it is
(A) Centrifugal pump
(B) Mixed flow pump
(C) Axial flow pump
(D) Any one of the above
Answer: b
21. If the ratios of all the corresponding linear dimensions are equal, then the model and the prototype are said to have
(A) Geometric similarity
(B) Kinematic similarity
(C) Dynamic similarity
(D) None of these
Answer: a
22. The optimum value of vane exit angle for a centrifugal pump impeller is
(A) 10-15°
(B) 20-25°
(C) 30-40°
(D) 50-60°
Answer: b
23. Which of the following pump is suitable for small discharge and high heads?
(A) Centrifugal pump
(B) Axial flow pump
(C) Mixed flow pump
(D) Reciprocating pump
Answer: d
24. For small discharge at high pressure, following pump is preferred
(A) Centrifugal
(B) Axial flow
(C) Mixed flow
(D) Reciprocating
Answer: b
25. A hydraulic press is a device used
(A) To store pressure energy which may be supplied to a machine later on
(B) To increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure
(C) To lift larger load by the application of a comparatively much smaller force
(D) All of the above
Answer: c
26. Low specific speed of turbine implies it is
(A) Propeller turbine
(B) Francis turbine
(C) Impulse turbine
(D) Any one of the above
Answer: c
27. The function of guide vanes in a reaction turbine is to
(A) Allow the water to enter the runner without shock
(B) Allow the water to flow over them, without forming eddies
(C) Allow the required quantity of water to enter the turbine
(D) All of the above
Answer: d
28. Hydraulic accumulator is used for
(A) Accumulating oil
(B) Supplying large quantities of oil for very short duration
(C) Generally high pressures to operate hydraulic machines
(D) Supplying energy when main supply fails
Answer: d
29. The jet ratio is defined as the ratio of the
(A) Diameter of jet to the diameter of Pelton wheel
(B) Velocity of jet to the velocity of Pelton wheel
(C) Diameter of Pelton wheel to the diameter of jet
(D) Velocity of Pelton wheel to the velocity of jet
Answer: c
30. Maximum impulse will be developed in hydraulic ram when
(A) Waste valve closes suddenly
(B) Supply pipe is long
(C) Supply pipe is short
(D) Ram chamber is large
Answer: a
31. In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowere(D) It can be done by
(A) Designing new impeller
(B) Trimming the impeller size to the required size by machining
(C) Not possible
(D) Some other alterations in the impeller
Answer: b
32. Which of the following pump is successfully used for lifting water to the turbines?
(A) Centrifugal pump
(B) Reciprocating pump
(C) Jet pump
(D) Air lift pump
Answer: c
33. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite (B)H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water , the horse power required will be
(A) Same
(B) 0.75 (B)H.P.
(C) (B)H.P./0.75
(D) 1.5 (B)H.P.
Answer: b
34. A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ____ of the jet velocity
(A) One-half
(B) One-third
(C) Two-third
(D) Three-fourth
Answer: b
35. In a centrifugal pump, the liquid enters the pump
(A) At the top
(B) At the bottom
(C) At the canter
(D) From sides
Answer: c
36. Kinematic similarity is said to exist between the model and the prototype, if both of them
(A) Have identical velocities
(B) Are equal in size and shape
(C) Are identical in shape, but differ only in size
(D) Have identical forces
Answer: a
37. For very high discharge at low pressure such as for flood control and irrigation applications, following type of pump is preferred
(A) Centrifugal
(B) Axial flow
(C) Reciprocating
(D) Mixed flow
Answer: b
38. The flow ratio of Francis turbine is defined as the ratio of the
(A) Velocity of flow at inlet to the theoretical jet velocity
(B) Theoretical velocity of jet to the velocity of flow at inlet
(C) Velocity of runner at inlet to the velocity of flow at inlet
(D) None of the above
Answer: a
39. The maximum number of jets generally employed in impulse turbine without jet interference is
(A) 4
(B) 6
(C) 8
(D) 12
Answer: b
40. The specific speed (Ns) of a centrifugal pump is given by
(A) (N√Q)/H2/3
(B) (N√Q)/H3/4
(C) (N√Q)/H
(D) (N√Q)/H5/4
Answer: b
41. . Medium specific speed of turbine implies it is
(A) Propeller turbine
(B) Francis turbine
(C) Impulse turbine
(D) Any one of the above
Answer: b
42. A turbine is required to develop 1500 kW at 300 r.p.m. under a head of 150 m. Which of the following turbine should be used?
(A) Pelton wheel with one nozzle
(B) Pelton wheel with two or more nozzles
(C) Kaplan turbine
(D) Francis turbine
Answer: a
43. Puck up the wrong statement about centrifugal pump
(A) Discharge a diameter
(B) Head a speed²
(C) Head a diameter
(D) Power a speed⁴
Answer: a
44. The flow ratio in case of Francis turbine varies from
(A) 0.15 to 0.3
(B) 0.4 to 0.5
(C) 0.6 to 0.9
(D) 1 to 1.5
Answer: a
45. In reaction turbine, draft tube is used
(A) To transport water downstream without eddies
(B) To convert the kinetic energy to flow energy by a gradual expansion of the flow cross-section
(C) For safety of turbine
(D) To increase flow rate
Answer: b
46. Air vessels in reciprocating pump are used to
(A) Smoothen flow
(B) Reduce acceleration to minimum
(C) Increase pump efficiency
(D) Save pump from cavitations
Answer: b
47. For 450 m head of water, ___ shall be use(D)
(A) Pelton wheel
(B) Kaplan turbine
(C) Francis turbine
(D) None of these
Answer: a
48. According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies
(A) Directly as fan speed
(B) Square of fan speed
(C) Cube of fan speed
(D) Square root of fan speed
Answer: a
49. The speed ratio in case of Francis turbine varies from
(A) 0.15 to 0.3
(B) 0.4 to 0.5
(C) 0.6 to 0.9
(D) 1 to 1.5
Answer: c
50. The specific speed of turbine is defined as the speed of a unit
(A) Of such a size that it delivers unit discharge at unit head
(B) Of such a size that it delivers unit discharge at unit power
(C) Of such a size that it requires unit power per unit head
(D)Of such a size that it produces unit horse power with unit head
Answer: d
51. The undershot water wheels are those in which
(A) The wheel runs entirely by the weight of water
(B)The wheel runs entirely by the impulse of water
(C) The wheel runs partly by the weight of water and partly by the impulse of water
(D) None of the above
Answer: b
