Lecturer in Machanical Engineering - Polytechnics-Technical Education (Question Paper)-116

4/14/2017
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  1. For flow through pipes, the maximum transmission efficiency that can achieve is:
    • 67%
    • 100%
    • 50%
    • 40%

  2. The unit of Chezy’s constant C in the Chezy’s formula is
    • m1/2/s
    • None of these
    • m/s
    • m/s2

  3. The ratio of the pitch diameter of Pelton wheel to the diameter of the jet is called:
    • Jet ratio
    • Speed ratio
    • Wheel ratio
    • None of these

  4. The hydraulic efficiency of a turbine with mean bucket diameter 1 m and running at 1000 rpm with net head 700 m when the side clearance angle is 15 degree and discharge of 100 liters/s is:
    • 97%
    • 60%
    • 70%
    • 85%

  5. The head loss due to friction for the flow of water through penstocks can be minimized by:
    • Increasing the diameter of penstock
    • Decreasing the diameter of penstock
    • Increasing the length of penstock
    • increasing the velocity of flow

  6. The head against which the centrifugal pump has to work is called:
    • Manometric head
    • Static head
    • Suction head
    • Delivery head

  7. An example of a turbine with high head and low specific speed is:
    • Pelton
    • Kaplan
    • Francis
    • None of these

  8. Which parameter remains constant during Joule-Thomson expansion?
    • Pressure
    • Temperature
    • Enthalpy
    • Volume

  9. For an ideal gas the compressibility factor is:
    • Unity
    • Zero
    • Infinity
    • None

  10. A heat pump works on reversed Carnot cycle has a COP of 5. If it works as a refrigerator taking 1kW of work input, the refrigerator effect will be:
    • 4kW
    • 1kW
    • 2kW
    • 3kW

  11. The value of Universal gas constant is
    • None of these
    • 8.314 J/kgK
    • 83.14 kJ/kgK
    • 8.3 14 kJ/kgK
    Value of Universal gas constant is 8.314 J / mol. K

  12. Which one of the following is the extensive property of the system?
    • Volume
    • Pressure
    • Temperature
    • Density

  13. Which parameter remains constant during a reversible adiabatic process?
    • Entropy
    • Enthalpy
    • temperature
    • Internal Energy

  14. Second law of thermodynamics defines
    • Entropy
    • Efficiency
    • Enthalpy
    • Internal Energy

  15. Which one of the following relation defines Helmholtz function F?
    • U - TS
    • H + TS
    • H - TS
    • U ÷ TS

  16. Which one of the following parameter is significant to ascertain chemical equilibrium of a system?
    • Gibbs Function
    • Helmholtz Function
    • Clapeyron equation
    • Maxwell reaction

  17. Which of the following cast iron consist of carbon in rosette form?
    • Malleable cast iron
    • White cast iron
    • Grey cast iron
    • Nodular cast iron

  18. Puddling is the process employed for converting:
    • Pig Iron into wrought iron
    • Iron ore into pig iron
    • Pig iron into cast iron
    • None of these

  19. Which is the magnetic allotrope of iron?
    • α iron
    • β iron
    • γ iron
    • None of these

  20. 18/8 stainless steel contains:
    • 18% Chromium, 8% Nickel
    • 18% Vanadium, 8% Chromium
    • 8% Tungaton, 8% Nickel
    • 18% Tungston, 8% Chromium

  21. Muntz metal contains copper and zinc in the ratio:
    • 3:2
    • 1:1
    • 2:3
    • 1:4

  22. Monel metal is an alloy of
    • Nickel and Copper
    • Copper and Chromium
    • Nickel and Chromium
    • None of these

  23. The hardness of a lathe bed material should be measured by:
    • Shore scleroscope
    • Brinell Hardness tester
    • Rockwell tester
    • Vickers Hardness tester

  24. White metal is an alloy of lead with:
    • Tin
    • Aluminium
    • Zinc
    • Bismuth

  25. Which one of the following is not an application of forging?
    • Steel balls of ball bearing
    • Rail sections
    • Chisels
    • Brake pedal of an automobile

  26. The electric resistance welding operates with:
    • High current and low voltage
    • Low current and high voltage
    • Low current and low voltage
    • High current and high voltage

  27. Spot welding, projection welding and seam welding belong to the category of:
    • Resistance welding
    • Arc welding
    • Thermit welding
    • Forge welding

  28. The number of Zones of heat generation in spot welding are:
    • 5
    • 2
    • 3
    • 7

  29. The ratio between oxygen and acetylene gases for neutral flame in gas welding is:
    • 1:1
    • 2:1
    • 1:2
    • 4:1

  30. Thermit used in thermit welding process is a mixture of:
    • Aluminium and Iron Oxide
    • CharcoL and Aluminium
    • Charcol and Iron Oxide
    • Charcol, Aluminium and Iron Oxide

  31. Which of the following welding methods uses pool of molten metal?
    • Submerged arc welding
    • Resistance welding
    • Plasma welding
    • None of these

  32. The welding zone in the TIG arc welding is shielded by an atmosphere of:
    • Helium
    • Oxygen Gas
    • CO2
    • Hydrogen

  33. Which of the following welding techniques uses a non consumable electrode?
    • TIG
    • MIG
    • Submerged arc
    • Thermit

  34. Vacuum environment is required in:
    • Electron beam welding
    • Ultrasonic welding
    • Laser beam welding
    • None of these

  35. High Speed electron beam of electron beam welding is focused on the weld spot using:
    • Magnetic lens
    • Vacuum lens
    • Inert gas lens
    • Optical lens

  36. Weld spatter is
    • a welding defect
    • an electrode
    • a flux
    • none of these

  37. A composite wall of a furnace has two layers of equal thickness with thermal conductivities in the ratio 3:2. What is the ratio of temperature drop across the two layers:
    • 2:3
    • 3:2
    • 1:2
    • None of these

  38. Critical thickness of insulation for a sphere with thermal conductivity k and convective heat transfer coefficient h is given by:
    • 2k/h
    • k/h
    • k/4h
    • k/2h

  39. For a perfectly black body: (α - Absorptivity, ρ - Reflectivity and τ- Transmitivity)
    • α=1, ρ=0, τ=0
    • α=ρ=0, τ=0
    • α=τ=0, ρ=0
    • None of these

  40. The intensity of solar radiation on earth is:
    • 1 kW/m2
    • 0.5 kW/m2
    • 2 kW/m2
    • 5 kW/m2

  41. If the temperature of a hot body is increased by 50% the amount of radiation emitted by it would increase by nearly:
    • 500%
    • 60%
    • 100%
    • 200%

  42. The value of shape factor for two infinite parallel planes separated by a distance x is:
    • 1
    • 0
    • 0.5
    • x

  43. The ratio of heat transfer by convection to that by conduction is called:
    • Nusselt Number
    • Stanton Number
    • Biot Nunaber
    • Peclet Number

  44. Which dimensionless number has a significant role in natural convection?
    • Grashoff’s Number
    • Peclet Number
    • Mach Number
    • None of these

  45. For the same operating temperature limits the COP of the heat pump equals:
    • 1 + COP of Refrigerator
    • COP of refrigerator
    • COP of Refrigerator -1
    • None of these

  46. A Carnot refrigerator rejects 3000 kJ of heat at 400 K while using 1000 kJ of work. The lowest operating temperature in the cycle should be about:
    • 267 K
    • 288 K
    • 300 K
    • 273 K

  47. During which component of vapour compression refrigeration system, the enthalpy remains constant:
    • Throttle Valve
    • Evaporator
    • compressor
    • None of these

  48. One tone of refrigeration is equal to:
    • 3.5kW
    • 5kW
    • 10kW
    • 125kW

  49. Knocking tendency in SI engine reduces with increasing:
    • Engine Speed
    • Compression Ratio
    • Wall temperature
    • None of these

  50. The two reference fuels used for cetane rating are:
    • Cetane and isooctane
    • Cetane and tetra ethyl lead
    • Cetane and alpha methyl naphthalene
    • None of these

  51. For a two stage reciprocating air compressor with perfect inter cooling the work input will be minimum if the supply pressure P1, the inter-cooler pressure P2 and the delivery pressure P3 satisfy the relation:
    • P2 = (P1*P2)0.5
    • P2 = (P1+P3)/2
    • P2 P1/P3
    • None of these

  52. Optimum pressure ratio for maximum specific output for ideal gas turbine power plant operating at initial temperature of 300 K and the maximum temperature of 1000 K is closer to:
    • 8
    • 4
    • 12
    • 16

  53. The use of regeneration in a gas turbine cycle increases:
    • Efficiency but has no effect on output
    • Output but has no effect on efficiency
    • Both efficiency and output
    • None of these

  54. Which one of the following is a lower pair?
    • Shaft in a bearing
    • Cam and follower
    • Toothed gearing
    • None of these

  55. The average tensions on the tight and slack side of a flat belt drive system are 700 N and 400 N respectively. If the linear velocity of the belt is 5 m/s, the power transmitted by the system would be about:
    • 1.5 kW
    • 3 kW
    • 5 kW
    • 10 kW

  56. In a 6 x 20 wire rope, number 6 indicates:
    • Number of strands in the wire rope
    • Diameter of the wire rope in mm
    • Number of wires
    • None of these

  57. The motion transmitted between the teeth of two spur gears is generally:
    • Partly sliding and partly rolling
    • Sliding
    • Rolling
    • Rotary

  58. The product of circular pitch and diametral pitch equals:
    • π
    • 1
    • Infinity
    • None of these

  59. In a flat belt drive, the belt can be subjected to maximum tension T and a centrifugal tension Tc. For maximum power transmission
    • T = 3Tc
    • T = Tc
    • T = 2Tc
    • T = 4Tc

  60. Which of the following is not a common section of V belts?
    • F
    • C
    • E
    • A

  61. A rack is a gear of infinite :
    • Diameter
    • Pitch
    • Module
    • Number of teeth

  62. The circular pitch of a toothed wheel with 24 teeth and a module of 4.25 mm is:
    • 13.35 mm
    • 1.35 mm
    • 4.25mm
    • 6.67 mm

  63. The maximum efficiency of a worm and worm wheel system in terms of friction angle φ is:
    • (1-sin φ)/(1+sin φ)
    • (1-cos φ)/(1+cos φ)
    • (1-sin φ)/(1+cos φ)
    • (1-tan φ)/(1+tan φ)

  64. In a multiple disc clutch n1 and n2 are the number of discs in the driving and driven shafts respectively. Then the number of pairs of contact surface is:
    • n1+n2-1
    • n1+n2
    • n1-n2
    • None of these

  65. The type of brakes commonly used in automobiles is:
    • Shoe brake
    • Band brake
    • Band and Block brake
    • None of these

  66. A reverted gear train is one in which the output and input shaft:
    • Are coaxial
    • Are at right angles to each other
    • Rotate in opposite directions
    • None of these

  67. When two spur gears having involute profiles on their teeth engage the line of action is tangential to:
    • Base circle
    • Pitch circle
    • Dedundum circle
    • Addendum circle

  68. A 60 mm long and 6 mm thick fillet weld carries a steady load of 15 kN along the weld. The shear strength of the weld material is 200 Mpa. The factor of safety is :
    • 3.4
    • 2.4
    • 1.8
    • 6.8

  69. In a butt weld joint the throat of weld as compared to size of the weld is in the ratio:
    • 1:1
    • 2:1
    • 1:2
    • 1:3

  70. A circular solid rod of diameter d welded to a right flat plate by a circular fillet weld of throat thickness t is subject to a twisting moment T. The maximum shear stress induced in the weld is
    • 2T/πtd2
    • 2T/πtd3
    • T/πtd2
    • 4T/πtd2

  71. In a BSW thread the angle between the flanks is:
    • 55°
    • 29°
    • 47.5°
    • 60°

  72. A high pressure angle for spur gears leads to:
    • Wide base and stronger teeth
    • Minimum axial thrust
    • More interference
    • None of these

  73. A worm has a lead angle of 22.5°. This corresponds to a helix angle of:
    • 67.5°
    • 22.5°
    • 45°
    • 55°

  74. The ratio between the mean diameter of the coil and diameter of wire is called:
    • Spring index
    • Spring rate
    • Spring Constant
    • Spring stiffness

  75. A spring with spring constant s has been cut into n equal parts. Each portion of the cut spring will have a spring constant, equal to:
    • ns
    • s
    • s/n
    • n/s

  76. Which of the following is not a friction clutch?
    • Jaw clutch
    • Plate clutch
    • Cone clutch
    • Centrifugal clutch

  77. The maximum stress induced in a spiral spring in terms of Moment applied M, breadth of strip b and thickness of strip t is:
    • 12M/bt2
    • 4M/bt2
    • 8M/bt2
    • 16M/bt2

  78. In design of helical springs the spring index is usually taken as:
    • 3
    • 10
    • 12
    • 16

  79. The stress induced in the circular section wire of a closed coil helical spring in terms of axial load W, mean coil diameter D and wire diameter d is:
    • 8WD/πd3
    • 12WD/πd3
    • 16WD/πd3
    • 32WD/πd3

  80. Spring stiffness is
    • Load per unit deflection
    • Load carrying capacity of the spring
    • Ratio of mean coil diameter to wire diameter
    • None of these

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