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MCQOPTIONS
This section includes 2670 Mcqs, each offering curated multiple-choice questions to sharpen your Railways knowledge and support exam preparation. Choose a topic below to get started.
| 2001. |
Rotating shafts tend to vibrate violently at whirling speeds because: |
| A. | The shafts are rotating at very high speeds |
| B. | Bearing centre line coincides with the shaft axis |
| C. | The system is unbalanced |
| D. | Resonance is caused due to the heavy weight of the rotor. |
| Answer» E. | |
| 2002. |
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. | Longitudinal vibrations provided the shaft is vertical. |
| Answer» B. Torsional vibrations | |
| 2003. |
In a automobile service station, an automobile is in a lifted up position by means of a hydraulic jack. A person working in the service station gave a tap to one rear wheel and made it rotate by one revolution. The rotation of another rear wheel is: |
| A. | Zero |
| B. | Also one revolution in the same direction |
| C. | Also one revolution but in the opposite direction |
| D. | unpredictable |
| Answer» C. Also one revolution but in the opposite direction | |
| 2004. |
A mass of 1 kg is attached to the end of a spring with a stiffness 0.7 N/mm. The critical damping coefficient of the system is: |
| A. | 1.40 Ns/m |
| B. | 52.22 Ns/m |
| C. | 52.92 Ns/m |
| D. | 529.20 Ns/m |
| Answer» D. 529.20 Ns/m | |
| 2005. |
Two heavy rotating masses are connected by shafts of lengths \[{{l}_{1}},{{l}_{2}}\] and \[{{l}_{3}}\] and the corresponding diameters are \[{{d}_{1}},{{d}_{2}}\] and \[{{d}_{3.}}\]this system is reduced to a torsionally equivalent system having uniform diameter \[''{{d}_{1}}''\] of the shaft. The equivalent length of the shaft is: |
| A. | \[\frac{{{l}_{1}}+{{l}_{2}}+{{l}_{3}}}{3}\] |
| B. | \[{{l}_{1}}+{{l}_{2}}{{\left( \frac{{{d}_{1}}}{{{d}_{2}}} \right)}^{3}}+{{l}_{3}}{{\left( \frac{{{d}_{1}}}{{{d}_{3}}} \right)}^{3}}\] |
| C. | \[{{l}_{1}}+{{l}_{2}}{{\left( \frac{{{d}_{1}}}{{{d}_{2}}} \right)}^{4}}+{{l}_{3}}{{\left( \frac{{{d}_{1}}}{{{d}_{3}}} \right)}^{4}}\] |
| D. | \[{{l}_{1}}+{{l}_{2}}+{{l}_{3}}\] |
| Answer» D. \[{{l}_{1}}+{{l}_{2}}+{{l}_{3}}\] | |
| 2006. |
The equation of free vibrations of a system is \[\ddot{x}+36\,\,{{\pi }^{2}}X=0.\] Its natural frequency is: |
| A. | \[46\text{ }Hz\] |
| B. | \[3\,\,\pi Hz\] |
| C. | \[3\text{ }Hz\] |
| D. | \[6\,\pi Hz\] |
| Answer» D. \[6\,\pi Hz\] | |
| 2007. |
Match the List I(Force transmissibility) with List II (frequency ratio) and select the correct answer using the codes given below the Lists: List-I (Force transmissibility) List-II (Frequency ratio) A. 1 1. \[\frac{\omega }{{{\omega }_{n}}}>\sqrt{2}\] B. Less than 1 2. \[\frac{\omega }{{{\omega }_{n}}}=\sqrt{2}\] C. Greater than 1 3. \[\frac{\omega }{{{\omega }_{n}}}>>\sqrt{2}\] D. Tending to zero 4. \[\frac{\omega }{{{\omega }_{n}}} |
| A. | A\[\to \]1, B\[\to \]2, C\[\to \]3, D\[\to \]4 |
| B. | A\[\to \]2, B\[\to \]1, C\[\to \]4, D\[\to \]3 |
| C. | A\[\to \]2, B\[\to \]1, C\[\to \]3, D\[\to \]4 |
| D. | A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]3 |
| Answer» C. A\[\to \]2, B\[\to \]1, C\[\to \]3, D\[\to \]4 | |
| 2008. |
The equation of motion for a single degree of freedom system with viscous damping is: \[4\ddot{x}+9\dot{x}+16x=0.\] The damping ratio of the system is: |
| A. | \[\frac{9}{128}\] |
| B. | \[\frac{9}{16}\] |
| C. | \[\frac{9}{8\sqrt{2}}\] |
| D. | \[\frac{9}{8}\] |
| Answer» C. \[\frac{9}{8\sqrt{2}}\] | |
| 2009. |
The critical speed of a rotating shaft depends |
| A. | Mass |
| B. | Stiffness |
| C. | Mass and stiffness |
| D. | Mass, stiffness and eccentricity. |
| Answer» D. Mass, stiffness and eccentricity. | |
| 2010. |
In a forced vibration with viscous damping, maximum amplitude occurs when forced frequency is: |
| A. | Equal to natural frequency |
| B. | Slightly less than natural frequency |
| C. | Slightly greater than natural frequency |
| D. | Zero |
| Answer» C. Slightly greater than natural frequency | |
| 2011. |
The value of the natural frequency obtained by Rayleigh's method: |
| A. | Is always greater than the actual fundamental frequency |
| B. | Is always less than the actual fundamental frequency |
| C. | Depends upon the initial deflection curve chosen and may be greater than or less than the actual fundamental frequency |
| D. | Is independent of the initial deflection curve chosen. |
| Answer» B. Is always less than the actual fundamental frequency | |
| 2012. |
In a multi-rotor system of torsional vibration maximum number of nodes that can occur is: |
| A. | Two |
| B. | Equal to the number of rotor plus one |
| C. | Equal to the number of rotors |
| D. | Equal to the number of rotors minus one |
| Answer» E. | |
| 2013. |
A rotating shaft carries a flywheel which overhangs on the bearing as a cantilever. If this flywheel weight is reduced to half of its original weight, the whirling speed will: |
| A. | Be double |
| B. | Increase by \[\sqrt{2}\] times |
| C. | Decrease by \[\sqrt{2}\] times |
| D. | Be half |
| Answer» C. Decrease by \[\sqrt{2}\] times | |
| 2014. |
The damping force in forced vibrations with reference to spring force: |
| A. | Leads by \[90{}^\circ \] |
| B. | Lags by \[90{}^\circ \] |
| C. | Leads by \[180{}^\circ \] |
| D. | Lags by \[180{}^\circ \] |
| Answer» C. Leads by \[180{}^\circ \] | |
| 2015. |
Match List-I with List-II and select the correct answer using the codes given below the Lists: List-I List-II A. 6 d.o.f. system 1. Vibrating beam B. 1 d.o.f. system 2. Vibration absorber C. 2 d.o.f. system 3. A rigid body in space D. Multi d.o.f. system 4. Pure rolling of a cylinder Codes: |
| A. | A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]5 |
| B. | A\[\to \]1, B\[\to \]4, C\[\to \]2, D\[\to \]3 |
| C. | A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1 |
| D. | A\[\to \]3, B\[\to \]4, C\[\to \]2, D\[\to \]1 |
| Answer» E. | |
| 2016. |
During torsional vibration of a shaft, the node is characterized by the: |
| A. | Maximum angular velocity |
| B. | Maximum angular displacement |
| C. | Maximum angular acceleration |
| D. | Zero angular displacement |
| Answer» E. | |
| 2017. |
A rod of uniform diameter is suspended from one of its ends in vertical plane. The mass of the rod is 'm' and length T, the natural frequency of this rod in Hz for small amplitude is: |
| A. | \[\frac{1}{2\pi }\sqrt{\frac{g}{l}}\] |
| B. | \[\frac{1}{2\pi }\sqrt{\frac{g}{3l}}\] |
| C. | \[\frac{1}{2\pi }\sqrt{\frac{2g}{3l}}\] |
| D. | \[\frac{1}{2\pi }\sqrt{\frac{3g}{2l}}\] |
| Answer» E. | |
| 2018. |
The mass moment of inertia of the two motors in a two rotor system arc \[100\,\,kg.{{m}^{2}}\] and \[10\,\,kg.{{m}^{2}}.\] the length of the shaft of uniform diameter between the rotors is 110 cm. The distance of node from the rotor of lower moment of inertia is: |
| A. | 80 cm |
| B. | 90 cm |
| C. | 100 cm |
| D. | 110 cm |
| Answer» D. 110 cm | |
| 2019. |
A shaft of 50 mm diameter and 1 m length carries a disc which has mass eccentricity equal to 190 microns. The displacement of the shaft at a speed which is 90% of critical speed in microns is: |
| A. | 810 |
| B. | 900 |
| C. | 800 |
| D. | 820 |
| Answer» B. 900 | |
| 2020. |
What is the number of nodes in a shalt carrying three rotors? |
| A. | Zero |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 2021. |
The deflection of a spring with 20 active turns under a load of 1000 N is 10 mm. The spring is made-into two pieces each of 10 active coils and placed in parallel under the same load. The deflection of this system is: |
| A. | 20 mm |
| B. | 10 mm |
| C. | 5 mm |
| D. | 2.5 mm |
| Answer» E. | |
| 2022. |
\[\frac{{{\partial }^{2}}u}{\partial {{t}^{2}}}={{c}^{2}}\frac{{{\partial }^{2}}u}{\partial {{t}^{2}}}\] represents the equation for: |
| A. | Vibration of a stretched string |
| B. | Motion of a projectile in a gravitational field |
| C. | Heat flow in thin rod |
| D. | Oscillation of a simple pendulum |
| Answer» B. Motion of a projectile in a gravitational field | |
| 2023. |
A flexible rotor-shaft system comprises of a 10 kg rotor disc placed in the middle of a massless shaft of diameter 30 mm and length 500 mm between bearings (shaft is being taken massless as the equivalent of the shaft, is included in the rotor mass) the ends. The bearings are assumed to simulate a supported boundary conditions. The shaft is made of steel for which the value of \[E=2.1\times {{10}^{11}}\]Pa. what is the critical speed of rotation of the shaft? |
| A. | 60 Hz |
| B. | 90 Hz |
| C. | 135 Hz |
| D. | 180 Hz |
| Answer» C. 135 Hz | |
| 2024. |
A vibrating machine is isolated from the floor using springs. If the ratio of excitation frequency of vibration of machine to the natural frequency of the isolation system is equal to 0.5, the transmissibility of ratio of isolation is: |
| A. | \[\frac{1}{2}\] |
| B. | \[\frac{3}{4}\] |
| C. | \[\frac{4}{3}\] |
| D. | 2 |
| Answer» D. 2 | |
| 2025. |
Which of the following methods can be used to determine the damping of machine element? 1. Logarithmic method 2. Band-width method 3. Rayleigh method 4. Holzer method, Select the correct answer using the codes given below: Codes: |
| A. | 1 and 3 |
| B. | 1 and 2 |
| C. | 3 and 4 |
| D. | 1, 3 and 4 |
| Answer» C. 3 and 4 | |
| 2026. |
If \[\frac{\omega }{{{\omega }_{n}}}=\sqrt{2}\] where \[\omega \] is the frequency of excitation and \[{{\omega }_{n}}\] is the natural frequency of vibrations, then the transmissibility of vibrations will be: |
| A. | 0.5 |
| B. | 1 |
| C. | 1.5 |
| D. | 2 |
| Answer» C. 1.5 | |
| 2027. |
A slender shaft supported on two hearings at its ends carries a disc with an eccentricity e from the axis of rotation. The critical speed of the shaft is N. If the disc is replaced by a second one of the same weight but mounted with an eccentricity 2e, critical speed of :he shaft in the second case is: |
| A. | \[\frac{1}{2}N\] |
| B. | \[\frac{1}{\sqrt{2}}N\] |
| C. | N |
| D. | 2N |
| Answer» D. 2N | |
| 2028. |
The rotor of a turbine is generally rotated at: |
| A. | The critical speed |
| B. | A speed much below the critical speed |
| C. | A speed much above the critical speed |
| D. | A speed having no relation to critical speed |
| Answer» D. A speed having no relation to critical speed | |
| 2029. |
A reed type tachometer uses the principle of: |
| A. | Torsional vibration |
| B. | Longitudinal vibration |
| C. | Transverse vibration |
| D. | Damped free vibration |
| Answer» D. Damped free vibration | |
| 2030. |
A viscous damping system with free vibrations will be critically damped if the damping factor is: |
| A. | zero |
| B. | less than one |
| C. | Equal to one |
| D. | greater than one |
| Answer» D. greater than one | |
| 2031. |
Consider the following statements: Two rotors mounted on a single shaft can be considered to be equivalent to a geared-shaft system having two rotors provided 1. The kinetic energy of the equivalent system is equal to that of the original system. 2. The strain energy of the equivalent system is equal to that of the original system. 3. The shaft diameters of the two systems are equal. Which of these statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 2 and 3 |
| D. | 1 and 3 |
| Answer» B. 1 and 2 | |
| 2032. |
In a system subjected to damped forced vibrations, the ratio of maximum displacement to the static deflection is known as: |
| A. | Critical damping ratio |
| B. | Damping factor |
| C. | Logarithmic decrement |
| D. | Magnification factor |
| Answer» E. | |
| 2033. |
A spring-mass suspension has a natural frequency of 40 rad/s. What is the damping ratio required if it is desired to reduce this frequency to 20 rad/s by adding a damper to it? |
| A. | \[\frac{\sqrt{3}}{2}\] |
| B. | \[\frac{1}{2}\] |
| C. | \[\frac{1}{\sqrt{2}}\] |
| D. | \[\frac{1}{4}\] |
| Answer» B. \[\frac{1}{2}\] | |
| 2034. |
Which one of the following is correct for a shaft carrying two rotors at its ends? |
| A. | It has no node |
| B. | It has one node |
| C. | It has two nodes |
| D. | It has three nodes |
| Answer» C. It has two nodes | |
| 2035. |
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 cycles/sec and 200 cycles/sec respectively. The lowest critical speed is: |
| A. | 5367 rpm |
| B. | 6000 rpm |
| C. | 9360 rpm |
| D. | 12,000 rpm |
| Answer» B. 6000 rpm | |
| 2036. |
A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural bow-shaded mode, it has a frequency of vibration of 10 radians second. When the shaft is rotated a 300 revolutions per minute, it will whirl with a radius of: |
| A. | 2 mm |
| B. | 225 mm |
| C. | 2.50 mm |
| D. | 3.00 mm |
| Answer» C. 2.50 mm | |
| 2037. |
If a piece of metal having a specific gravity of 13.6 is placed in mercury of specific gravity 13.6, then: |
| A. | The metal piece will sink to the bottom |
| B. | The metal piece will simply float over the mercury with no immersion |
| C. | The metal piece will be immersed in mercury by half |
| D. | The whole of the metal piece will be immersed with its top surface just at mercury level |
| Answer» E. | |
| 2038. |
The least radius of gyration of a ship is 9 m and the metacentric height is 750 mm. The time period of oscillation of the ship is: |
| A. | 42.41 s |
| B. | 75.4 s |
| C. | 20.85 s |
| D. | 85 s |
| Answer» D. 85 s | |
| 2039. |
A bucket of water hangs with a spring balance. If an iron piece is suspended into water from another support without touching the sides of the bucket, the spring balance will show: |
| A. | An increased reading |
| B. | A decreased reading |
| C. | No change in reading |
| D. | Increased or decreased reading depending on the depth of immersion |
| Answer» D. Increased or decreased reading depending on the depth of immersion | |
| 2040. |
For an opaque plane surface, the irradiation, radiosity and emissive power are respectively 20, 12 and \[10\,\,\text{W/}{{\text{m}}^{\text{2}}}.\] what is the emissivity of the surface? |
| A. | 0.2 |
| B. | 0.4 |
| C. | 0.8 |
| D. | 1 |
| Answer» D. 1 | |
| 2041. |
Two long parallel surfaces, each of emissivity 0.7, are maintained at different temperatures and accordingly have radiation exchange between them. It is desired to reduce 75% of this radiant heat transfer by inserting thin parallel shields of equal emissivity (0.7) on both sides. What would be the number of shields? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 2042. |
The earth receives at its surface radiation from the sun at the rate of \[1400\,\,\text{W/}{{\text{m}}^{\text{2}}}.\] the distance of centre of sun from the surface of earth is \[1.5\times {{10}^{11}}m\] and the radius of sun is \[7.0\times {{10}^{8}}M.\] what is approximately the surface temperature of the sun treating the sun as a black body? |
| A. | 3650 K |
| B. | 4500 K |
| C. | 5800 K |
| D. | 6150 K |
| Answer» D. 6150 K | |
| 2043. |
A copper wire of radius 0.5 mm is insulated with a sheathing of thickness 1 mm having a thermo- conductivity of 05 W/m.K. The outside surface convective heat transfer coefficient is 10 W/m.K. If the thickness of insulation sheathing is raised by 10 mm, then the electrical current carrying capacity of the wire will: |
| A. | Increase |
| B. | Decrease |
| C. | Remain the same |
| D. | Vary depending upon the electric conductivity of the wire. |
| Answer» D. Vary depending upon the electric conductivity of the wire. | |
| 2044. |
A composite plane wall is made up of two different materials of the same thickness and having thermal conductivities of \[{{k}_{1}}\] and \[{{k}_{2}}\] respectively. The equivalent thermal conductivity of the slab is: |
| A. | \[{{k}_{1}}+{{k}_{2}}\] |
| B. | \[{{k}_{1}}{{k}_{2}}\] |
| C. | \[\frac{{{k}_{1}}+{{k}_{2}}}{{{k}_{1}}{{k}_{2}}}\] |
| D. | \[\frac{2{{k}_{1}}{{k}_{2}}}{{{k}_{1}}+{{k}_{2}}}\] |
| Answer» E. | |
| 2045. |
For the fully developed laminar flow and the transfer in a uniformly heated long circular tube, if the velocity is doubled and the tube diameter is halved, the heat transfer coefficient will be: |
| A. | Double of the original value |
| B. | Half of the original value |
| C. | Same as before |
| D. | Four times of the original value. |
| Answer» D. Four times of the original value. | |
| 2046. |
The flash chamber in a single stage simple vapour compression cycle: |
| A. | Increase the refrigerating effect |
| B. | Decreases the refrigerating effect |
| C. | Increases the work of compression |
| D. | Has no effect on refrigerating effect |
| Answer» E. | |
| 2047. |
Air refrigeration cycle is used in: |
| A. | Commercial refrigerators |
| B. | Domestic refrigerators |
| C. | Gas liquefaction |
| D. | Air-conditioning |
| Answer» B. Domestic refrigerators | |
| 2048. |
Consider the following statements: In a vapour compression system, a thermometer placed in the liquid line can indicate whether the: 1. Refrigerant flow is too low 2. Water circulation is adequate. 3. Condenser is fouled. 4. Pump is functioning properly. Of these statement: |
| A. | 1, 2 and 3 are correct |
| B. | 1, 2 and 4 are correct |
| C. | 1, 3 and 4 are correct |
| D. | 2, 3 and 4 are correct |
| Answer» E. | |
| 2049. |
High frequency for induction heating can be generated by |
| A. | motor generator set |
| B. | spark gap oscillator |
| C. | vacuum tube oscillator |
| D. | all of these |
| Answer» C. vacuum tube oscillator | |
| 2050. |
The dc series motor is most suitable for tranction services but more particularly for urban/suburban services because |
| A. | dc series motors are suitable for regenerative braking |
| B. | dc series motors are capable of withstanding rapid fluctuations in supply voltage |
| C. | dc series motors are capable of developing high torque at start |
| D. | de series motors are capable of withstanding temporary interruption of supply without undue rush of current |
| Answer» D. de series motors are capable of withstanding temporary interruption of supply without undue rush of current | |