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This section includes 198 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
51. |
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» D. velocity of Pelton wheel to the velocity of jet | |
52. |
A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit speed of the wheel is |
A. | 10 r.p.m. |
B. | 20 r.p.m. |
C. | 40 r.p.m. |
D. | 80 r.p.m. |
Answer» C. 40 r.p.m. | |
53. |
A Francis turbine is an outward flow reaction turbine. |
A. | True |
B. | False |
C. | Can't say |
D. | None of these |
Answer» C. Can't say | |
54. |
Mechanical efficiency of a centrifugal pump is the ratio of |
A. | energy available at the impeller to the energy supplied to the pump by the prime mover |
B. | actual workdone by the pump to the energy supplied to the pump by the prime mover |
C. | energy supplied to the pump to the energy available at the impeller |
D. | manometric head to the energy supplied by the impeller per kN of water |
Answer» B. actual workdone by the pump to the energy supplied to the pump by the prime mover | |
55. |
The force exerted (in newton) by a jetof water impinging normally on a fixed plate is (where w = Specific weight of water in N/m³, a = Cross-sectional area of jet in m², and V = Velocity of jet in m/s) |
A. | waV / 2g |
B. | waV / g |
C. | waV² / 2g |
D. | waV² / g |
Answer» E. | |
56. |
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» C. the wheel runs partly by the weight of water and partly by the impulse of water | |
57. |
The specific speed (Ns) of a centrifugal pump is given by |
A. | (N√Q)/H^2/3 |
B. | (N√Q)/H^3/4 |
C. | (N√Q)/H |
D. | (N√Q)/H5/4 |
Answer» C. (N√Q)/H | |
58. |
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» B. 0.4 to 0.5 | |
59. |
In a Francis turbine runner, the number of blades are generally between |
A. | 2 to 4 |
B. | 4 to 8 |
C. | 8 to 16 |
D. | 16 to 24 |
Answer» E. | |
60. |
The efficiency of a reaction turbine for a given head __________ with the increase in speed. |
A. | decreases |
B. | increases |
C. | Can't say |
D. | None of these |
Answer» B. increases | |
61. |
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» C. two-third | |
62. |
The Thomson's turbine is __________ reaction turbine. |
A. | an axial flow |
B. | an inward flow |
C. | an outward flow |
D. | a mixed flow |
Answer» C. an outward flow | |
63. |
The runaway speed of a hydraulic turbine is the speed |
A. | at full load |
B. | at which there will be no damage to the runner |
C. | corresponding to maximum overload permissible |
D. | at which the turbine will run freely without load |
Answer» E. | |
64. |
The hydraulic efficiency of an impulse turbine is maximum when velocity of wheel is __________ of the jet velocity, |
A. | one-fourth |
B. | one-half |
C. | three-fourth |
D. | double |
Answer» C. three-fourth | |
65. |
A draft tube is used with impulse turbines. |
A. | Yes |
B. | No |
C. | Can't say |
D. | None of these |
Answer» C. Can't say | |
66. |
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» D. Air lift pump | |
67. |
For 450 m head of water, __________ shallbeused. |
A. | Pelton wheel |
B. | Kaplan turbine |
C. | Francis turbine |
D. | none of these |
Answer» B. Kaplan turbine | |
68. |
In a reaction turbine, the water enters the wheel under pressure and flows over the vanes. |
A. | Correct |
B. | Incorrect |
C. | Can't say |
D. | None of these |
Answer» B. Incorrect | |
69. |
The air vessel, in a reciprocating pump, is a cast iron closed chamber having an opening at its base. |
A. | Agree |
B. | Disagree |
C. | Can't say |
D. | None of these |
Answer» B. Disagree | |
70. |
By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power.The saving in case of a double acting reciprocating pump is |
A. | 39.2% |
B. | 48.8% |
C. | 84.8% |
D. | 88.4% |
Answer» B. 48.8% | |
71. |
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» B. are equal in size and shape | |
72. |
In an axial flow reaction turbine, the water flows __________ to the axis of the wheel. |
A. | parallel |
B. | perpendicular |
C. | Can't say |
D. | None of these |
Answer» B. perpendicular | |
73. |
The head available at the inlet of the turbine is known as net or effective head. |
A. | Correct |
B. | Incorrect |
C. | Can't say |
D. | None of these |
Answer» B. Incorrect | |
74. |
The power developed by a turbine is (where H = Head of water under which the turbine is working) |
A. | directly proportional to H^1/2 |
B. | inversely proportional to H^1/2 |
C. | directly proportional to H^3/2 |
D. | inversely proportional to H^3/2 |
Answer» D. inversely proportional to H^3/2 | |
75. |
A hydraulic ram is a device used to |
A. | store the energy of water |
B. | increase the pressure of water |
C. | to lift water from deep wells |
D. | to lift small quantity of water to a greater height when a large quantity of water is available at a smaller height |
Answer» E. | |
76. |
The unit speed of the turbine runner is |
A. | N/√H |
B. | N/H |
C. | N/H^3/2 |
D. | N/H² |
Answer» B. N/H | |
77. |
A hydraulic intensifier is a device used to increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure. |
A. | Correct |
B. | Incorrect |
C. | Can't say |
D. | None of these |
Answer» B. Incorrect | |
78. |
The efficiency of jet propulsion for a ship with inlet orifices at right angles to the direction of motion of ship, will be maximum when the relative velocity of the jet and ship is equal to twice the velocity of the ship. |
A. | Yes |
B. | No |
C. | Can't say |
D. | None of these |
Answer» B. No | |
79. |
The efficiency of a hydraulic press is given by (where W = Weight lifted by ram, P = Force applied on plunger, A = Area of ram, and a = Area of plunger) |
A. | (W/p) × (A/a) |
B. | (p/W) × (a/A) |
C. | (W/p) × (a/A) |
D. | (p/W) × (A/a) |
Answer» D. (p/W) × (A/a) | |
80. |
Slip of a reciprocating pump is negative, when |
A. | suction pipe is short and pump is running at low speeds |
B. | delivery pipe is long and pump is running at high speeds |
C. | suction pipe is short and delivery pipe is long and the pump is running at low speeds |
D. | suction pipe is long and delivery pipe is short and the pump is running at high speeds |
Answer» E. | |
81. |
A Pelton wheel working under a constant head and discharge, has maximum efficiency when the speed ratio is |
A. | 0.26 |
B. | 0.36 |
C. | 0.46 |
D. | 0.56 |
Answer» D. 0.56 | |
82. |
The working of which of the following hydraulic units is based on Pascal's law? |
A. | Air lift pump |
B. | Jet pump |
C. | Hydraulic coupling |
D. | Hydraulic press |
Answer» E. | |
83. |
A turbine develops 10000 kW under a head of 25 metres at 135 r.p.m. Its specific speed is |
A. | 175.4 r.p.m. |
B. | 215.5 r.p.m. |
C. | 241.5 r.p.m. |
D. | 275.4 r.p.m |
Answer» D. 275.4 r.p.m | |
84. |
In a mixed flow centrifugal pump, the flow through the impeller is a combination of radial and axial flows. |
A. | Correct |
B. | Incorrect |
C. | Can't say |
D. | None of these |
Answer» B. Incorrect | |
85. |
A reciprocating pump is suitable for less discharge and higher heads. |
A. | True |
B. | False |
C. | Can't say |
D. | None of these |
Answer» B. False | |
86. |
The ratio of the normal force of jet of water on a plate inclined at an angle of 30° as compared to that when the plate is normal to jet, is |
A. | 1/2 |
B. | 1/2 |
C. | 1 |
D. | 2 |
Answer» D. 2 | |
87. |
Which of the following pump is generally used to pump highly viscous fluid? |
A. | Centrifugal pump |
B. | Reciprocating pump |
C. | Air lift pump |
D. | Screw pump |
Answer» E. | |
88. |
Dynamic 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. | none of the above |
Answer» E. | |
89. |
Delivery head of a centrifugal pump is |
A. | directly proportional to N |
B. | inversely proportional to N |
C. | directly proportional to N² |
D. | inversely proportional to N² |
Answer» D. inversely proportional to N² | |
90. |
Power required (in watts) to drive a centrifugal pump is (where Hm = Manometric head in metres, w = Specific weight in N/m³, Q = Discharge of the pump in m³/s, and ηo = Overall efficiency of the pump) |
A. | (w Hm) / (Q × ηo) |
B. | (w Hm Q) / ηo |
C. | (w Q) / (Hm × ηo) |
D. | (w Q ηo) / Hm |
Answer» C. (w Q) / (Hm × ηo) | |
91. |
The Furneyron turbine is __________ reaction turbine. |
A. | an axial flow |
B. | an inward flow |
C. | an outward flow |
D. | a mixed flow |
Answer» D. a mixed flow | |
92. |
The discharge through a turbine is |
A. | directly proportional to H^1/2 |
B. | inversely proportional to H^1/2 |
C. | directly proportional to H^3/2 |
D. | inversely proportional to H^3/2 |
Answer» B. inversely proportional to H^1/2 | |
93. |
The cavitation in a hydraulic machine is mainly due to |
A. | low velocity |
B. | high velocity |
C. | low pressure |
D. | high pressure |
Answer» D. high pressure | |
94. |
Manometric head is the actual head of water against which a centrifugal pump has to work. |
A. | Correct |
B. | Incorrect |
C. | Can't say |
D. | None of these |
Answer» B. Incorrect | |
95. |
Overall efficiency of a centrifugal pump is the ratio of |
A. | energy available at the impeller to the energy supplied to the pump by the prime mover |
B. | actual workdone by the pump to the energy supplied to the pump by the prime mover |
C. | energy supplied to the pump to the energy available at the impeller |
D. | manometric head to the energy supplied by the impeller per kN of water |
Answer» C. energy supplied to the pump to the energy available at the impeller | |
96. |
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» E. | |
97. |
The discharge through a reaction turbine __________ with the increase in unit speed. |
A. | remains same |
B. | increases |
C. | decreases |
D. | None of these |
Answer» D. None of these | |
98. |
In an outward flow reaction turbine |
A. | the water flows parallel to the axis of the wheel |
B. | the water enters at the centre of the wheel and then flows towards the outer periphery of the wheel |
C. | the water enters the wheel at the outer periphery and then flows towards the centre of the wheel |
D. | the flow of water is partly radial and partly axial |
Answer» C. the water enters the wheel at the outer periphery and then flows towards the centre of the wheel | |
99. |
The gross or total head of the turbine is the __________ of the water levels at the head race and tail race. |
A. | sum |
B. | difference |
C. | product |
D. | None of these |
Answer» C. product | |
100. |
The speed of a turbine runner is |
A. | directly proportional to H^1/2 |
B. | inversely proportional to H^1/2 |
C. | directly proportional to H^3/2 |
D. | inversely proportional to H^3/2 |
Answer» B. inversely proportional to H^1/2 | |