McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 51. |
Which of the following statements is correct about the balancing of a mechanical system? |
| A. | if it is under static balance, then there will be dynamic balance also |
| B. | if it is under dynamic balance, then there will be static balance also |
| C. | both static as well as dynamic balance have to be achieved separately |
| D. | none of the mentioned |
| Answer» C. both static as well as dynamic balance have to be achieved separately | |
| 52. |
In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large in order to |
| A. | minimize the effect of primary forces |
| B. | minimize the effect of secondary forces |
| C. | have perfect balancing |
| D. | start the locomotive conveniently |
| Answer» B. minimize the effect of secondary forces | |
| 53. |
In case of partial balancing of locomotives, the maximum magnitude of the unbalanced force perpendicular to the line of stroke is called hammer blow and this has to be limited by proper choice of the balancing mass and its radial position. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 54. |
Multi-cylinder engines are desirable because |
| A. | only balancing problems are reduced |
| B. | only flywheel size is reduced |
| C. | both (a) and (b) |
| D. | none of the mentioned |
| Answer» C. both (a) and (b) | |
| 55. |
Secondary forces in reciprocating mass on engine frame are |
| A. | of same frequency as of primary forces |
| B. | twice the frequency as of primary forces |
| C. | four times the frequency as of primary forces |
| D. | none of the mentioned |
| Answer» B. twice the frequency as of primary forces | |
| 56. |
Which of the following process is not the part of working of a 4 stroke I.C Engine? |
| A. | compression |
| B. | suction |
| C. | exhaust |
| D. | turbine flow |
| Answer» D. turbine flow | |
| 57. |
4-stroke engine has one power stroke per 2 revolutions hence turning moment diagram is uniform. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 58. |
Work produced by the 4-stroke engine is less because |
| A. | one power stroke per 2 revolutions |
| B. | one power stroke per revolution |
| C. | one power stroke per 4 revolution |
| D. | four power stroke per revolution |
| Answer» A. one power stroke per 2 revolutions | |
| 59. |
A negative loop is formed in the turning moment diagram because the pressure inside the cylinder is than the atmospheric pressure. |
| A. | equal |
| B. | more |
| C. | less |
| D. | no pressure inside |
| Answer» C. less | |
| 60. |
When the work is by on the gases, which of the following effect is observed on the turning moment diagram? |
| A. | formation of negative loop |
| B. | formation of positive loop |
| C. | formation of an infinite loop |
| D. | formation of no loop |
| Answer» B. formation of positive loop | |
| 61. |
Compression stroke results in |
| A. | formation of negative loop |
| B. | formation of positive loop |
| C. | formation of an infinite loop |
| D. | formation of no loop |
| Answer» A. formation of negative loop | |
| 62. |
4 strokes engine have a lower thermal efficiency than 2 stroke engine. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 63. |
While drawing the turning moment diagram, which of the forces in not taken into account? |
| A. | inertia force |
| B. | force on connecting rod |
| C. | force on crank |
| D. | coriolis force |
| Answer» D. coriolis force | |
| 64. |
In the given turning moment diagram, the process X is known as |
| A. | suction |
| B. | compression |
| C. | power |
| D. | exhaust |
| Answer» C. power | |
| 65. |
3 BALANCING MACHINES-FIELD BALANCING OF DISCS AND ROTORS. |
| A. | centripetal forces |
| B. | centrifugal forces |
| C. | friction forces |
| D. | inertia forces |
| Answer» D. inertia forces | |
| 66. |
Balancing of single rotating mass by balancing masses in same plane and in different planes cannot take place. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 67. |
Which of the following is true for centrifugal force causing unbalance? |
| A. | direction changes with rotation |
| B. | magnitude changes with rotation |
| C. | direction and magnitude both change with rotation |
| D. | direction and magnitude both remain unchanged with rotation |
| Answer» A. direction changes with rotation | |
| 68. |
In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of the rotor lies |
| A. | below the axis of shaft |
| B. | on the axis of the shaft |
| C. | above the axis of shaft |
| D. | away from the axis of shaft |
| Answer» B. on the axis of the shaft | |
| 69. |
If the unbalanced system is not set right then. |
| A. | static forces develop |
| B. | dynamic forces develop |
| C. | tangential forces develop |
| D. | radial forces develop |
| Answer» A. static forces develop | |
| 70. |
What is not the effect of unbalanced forces? |
| A. | load on bearings |
| B. | dangerous vibrations |
| C. | stresses in various members |
| D. | violation of conservation of mass principle |
| Answer» D. violation of conservation of mass principle | |
| 71. |
What is the effect of a rotating mass of a shaft on a system? |
| A. | bend the shaft |
| B. | twist the shaft |
| C. | extend the shaft |
| D. | compress the shaft |
| Answer» A. bend the shaft | |
| 72. |
Balancing of reciprocating masses is the process of providing the second mass in order to counteract the effect of the centrifugal force of the first mass. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 73. |
The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in |
| A. | transverse vibrations |
| B. | torsional vibrations |
| C. | longitudinal vibrations |
| D. | none of the mentioned |
| Answer» A. transverse vibrations | |
| 74. |
When there is a reduction in amplitude over every cycle of vibration, then the body is said to have |
| A. | free vibration |
| B. | forced vibration |
| C. | damped vibration |
| D. | under damped vibration |
| Answer» C. damped vibration | |
| 75. |
In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be |
| A. | less than unity |
| B. | equal to unity |
| C. | greater than unity |
| D. | zero |
| Answer» C. greater than unity | |
| 76. |
The accelerometer is used as a transducer to measure earthquake in Richter scale. Its design is based on the principle that |
| A. | its natural frequency is very low in comparison to the frequency of vibration |
| B. | its natural frequency is very high in comparison to the frequency of vibration |
| C. | its natural frequency is equal to the frequency of vibration |
| D. | measurement of vibratory motion is without any reference point |
| Answer» C. its natural frequency is equal to the frequency of vibration | |
| 77. |
Critical speed is expressed as |
| A. | rotation of shaft in degrees |
| B. | rotation of shaft in radians |
| C. | rotation of shaft in minutes |
| D. | natural frequency of the shaft |
| Answer» D. natural frequency of the shaft | |
| 78. |
The first critical speed of an automobile running on a sinusoidal road is calculated by (modeling it as a single degree of freedom system) |
| A. | resonance |
| B. | approximation |
| C. | superposition |
| D. | rayleigh quotient |
| Answer» A. resonance | |
| 79. |
The natural frequency of a spring-mass system on earth is ωn. The natural frequency of this system on the moon (gmoon = gearth/6) is |
| A. | ωn |
| B. | 0.408ωn |
| C. | 0.204ωn |
| D. | 0.167ωn |
| Answer» A. ωn | |
| 80. |
A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural frequency (fn), respectively, are |
| A. | 0.471 and 1.19 hz |
| B. | 0.471 and 7.48 hz |
| C. | 0.666 and 1.35 hz |
| D. | 0.666 and 8.50 hz |
| Answer» A. 0.471 and 1.19 hz | |
| 81. |
If the crank and the connecting rod are 300 mm and 1 m long respectively and the crank rotates at a constant speed of 250 r.p.m., determine the crank angle at which the maximum velocity occurs is |
| A. | 45 |
| B. | 75 |
| C. | 90 |
| D. | 60 |
| Answer» B. 75 | |
| 82. |
5 m/s. |
| A. | 4.19 |
| B. | 5 |
| C. | 3.49 |
| D. | 3.36 |
| Answer» C. 3.49 | |
| 83. |
Which of the following expression represent the angular acceleration α of the connecting rod? |
| A. | −ω2 . sin θ/n |
| B. | −ω2 . cos θ.n |
| C. | ω2. cos θ/n |
| D. | ω2 . sin θ.n |
| Answer» A. −ω2 . sin θ/n | |
| 84. |
While calculating angular acceleration of the connecting rod, sin2(θ) term is neglected. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 85. |
In a slider crank mechanism, the length of the crank and connecting rod are 180 mm and 540 mm respectively. The crank position is 45° from inner dead centre. The crank shaft speed is 450 r.p.m. (clockwise), calculate angular velocity of the connecting rod in rad/s. |
| A. | 10.3 |
| B. | 11.1 |
| C. | 12.2 |
| D. | 11.8 |
| Answer» B. 11.1 | |
| 86. |
When a body is subjected to transverse vibrations, the stress induced in a body will be |
| A. | shear stress |
| B. | bending stress |
| C. | tensile stress |
| D. | compressive stress |
| Answer» B. bending stress | |
| 87. |
For an under damped harmonic oscillator, resonance |
| A. | occurs when excitation frequency is greater than undamped natural frequency |
| B. | occurs when excitation frequency is less than undamped natural frequency |
| C. | occurs when excitation frequency is equal to undamped natural frequency |
| D. | never occurs |
| Answer» C. occurs when excitation frequency is equal to undamped natural frequency | |
| 88. |
When there is a reduction in amplitude over every cycle of vibration, then the body is said to have |
| A. | free vibration |
| B. | forced vibration |
| C. | damped vibration |
| D. | none of the mentioned |
| Answer» C. damped vibration | |
| 89. |
Longitudinal vibrations are said to occur when the particles of a body moves |
| A. | perpendicular to its axis |
| B. | parallel to its axis |
| C. | in a circle about its axis |
| D. | none of the mentioned |
| Answer» B. parallel to its axis | |
| 90. |
When a body is subjected to transverse vibrations, the stress induced in a body will be |
| A. | shear stress |
| B. | tensile stress |
| C. | compressive stress |
| D. | none of the mentioned |
| Answer» B. tensile stress | |
| 91. |
The natural frequency (in Hz) of free longitudinal vibrations is equal to |
| A. | 1/2π√s/m |
| B. | 1/2π√g/δ |
| C. | 0.4985/δ |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 92. |
The factor which affects the critical speed of a shaft is |
| A. | diameter of the disc |
| B. | span of the shaft |
| C. | eccentricity |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 93. |
In under damped vibrating system, if x1 and x2 are the successive values of the amplitude on the same side of the mean position, then the logarithmic decrement is equal to |
| A. | x1/x2 |
| B. | log (x1/x2) |
| C. | loge (x1/x2) |
| D. | log (x1.x2) |
| Answer» B. log (x1/x2) | |
| 94. |
The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as |
| A. | damping factor |
| B. | damping coefficient |
| C. | logarithmic decrement |
| D. | magnification factor |
| Answer» D. magnification factor | |
| 95. |
Which of the following systems produce a vibration in the foundation? |
| A. | unbalanced machine |
| B. | balanced machine |
| C. | coupled machine |
| D. | uncoupled machine |
| Answer» A. unbalanced machine | |
| 96. |
When a periodic disturbing force is applied to a machine, the force is transmitted to the foundation by the means of spring. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 97. |
Which of the following is correct regarding isolation factor? |
| A. | dimensionless quantity |
| B. | has newton as its unit |
| C. | has joule as its unit |
| D. | has hz as its unit |
| Answer» A. dimensionless quantity | |
| 98. |
Which of the following is a type of transmitted force to the foundation? |
| A. | damping force |
| B. | undamping force |
| C. | tensile force |
| D. | torsional force |
| Answer» A. damping force | |
| 99. |
If isolation factor is negative, then what is the phase difference between transmitted and disturbing force? |
| A. | 180° |
| B. | 90° |
| C. | 450° |
| D. | 360° |
| Answer» A. 180° | |
| 100. |
Which of the following is true regarding Ɛ>1? |
| A. | transmitted force is greater than applied force |
| B. | transmitted force is less than applied force |
| C. | spring force is less than applied force |
| D. | damping force is less than applied force |
| Answer» A. transmitted force is greater than applied force | |
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