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Machine Design MCQ Set 1

1. The sum of the shape functions over the element is always equal to:
a) Zero
b) Infinity
c) Unity
d) None of the mentioned

View Answer

Answer: c [Reason:] A shape function is always equal to one at its designated node and zero at the other nodes of the element.

2. Stiffness is ______________ to the length of the element.
a) Inversely proportional
b) Directly proportional
c) Exponential
d) Independent

View Answer

Answer: d [Reason:] None.

3. Computer will perform the data processing functions in
a) NC
b) CNC
c) DNC
d) ACS

View Answer

Answer: c [Reason:] In NC it performs numerical problems. In DNC it will perform data processing functions.

4. The first commercial CNC machine was developed in the year:
a) 1970
b) 1972
c) 1976
d) 1980

View Answer

Answer: a [Reason:] The first NC machines were built in the 1940s and 1950s. CNC was developed in 1970.

5. CNC drilling machine is considered to be a:
a) Point-to-point controlled machine
b) Straight line controlled machine
c) Continuous path controlled machine
d) Servo-controlled machine

View Answer

Answer: a [Reason:] None.

6. The lost motion in CNC machine tool is on account of:
a) Backlash in gearing
b) Wind-up of drive shafts
c) Deflection of machine tool members
d) All of the mentioned

View Answer

Answer: a [Reason:] The system must provide sufficient feedback and programming capacity to allow for backlash and lost motion between motor and load. Computer numerical control (CNC) of machine tools has embodied position control for a number of years.

7. The axes of turning machine arc:
a) Z and X-axes
b) X and Y-axes
c) Z and Y-axes
d) X, Y and Z-axes

View Answer

Answer: a [Reason:] None.

8. On turning lathes the machine zero point is generally at the:
a) Head stock of lathe spindle nose face
b) Dead center of tail stock
c) Tool point mounted on tool post
d) none of the mentioned

View Answer

Answer: b [Reason:] On turning lathes, the machine zero point is generally at the centre of the spindle nose face.

9. Dwell is defined by:
a) G04
b) G03
c) G02
d) G01

View Answer

Answer: a [Reason:] G02 – Circular interpolation in clockwise direction G91 – incremental dimension.

10. M30 stands for:
a) End of program
b) End of block
c) End of tape and tape rewind
d) Coolant on/ off

View Answer

Answer: a [Reason:] M30 – Program Stopping and Ending.

Machine Design MCQ Set 2

1. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.
a) True
b) False

View Answer

Answer: a [Reason:] In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. The method will reduce length of effective stroke of piston. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.

2. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the steam lap and the angle of the eccentric but keeping constant the travel and lead of the valve. This method will
a) cause withdrawing or throttling of steam
b) reduce length of effective stroke of piston
c) reduce maximum opening opening of port to steam
d) all of the mentioned

View Answer

Answer: c [Reason:] In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the steam lap and the angle of the eccentric but keeping constant the travel and lead of the valve. This method will reduce maximum opening opening of port to steam. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. The method will reduce length of effective stroke of piston. In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve may be obtained by increasing the angle of advance of the eccentric but reducing the throw of the eccentric and keeping the steam lap and exhaust lap constant. The method will cause withdrawing or throttling of steam.

3. In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from
a) 100-150
b) 150-250
c) 250-300
d) 300-400

View Answer

Answer: c [Reason:] In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from 250-300 and the expansion valve is driven by an eccentric having angle of advance 800-900.

4. The virtue or equivalent eccentric for the Meyer’s expansion valve is defined as an eccentric having such a length and angle of advance that will cause cut-off to take place at the same position, as is caused by the combined effect of main eccentric and expansion eccentric.
a) True
b) False

View Answer

Answer: a [Reason:] None

5. In Meyer’s expansion valve, the expansion valve is driven by an eccentric having an angle of advance from
a) 500-600
b) 600-700
c) 700-80
d) 800-900

View Answer

Answer: d [Reason:] In Meyer’s expansion valve, the main valve is driven by an eccentric having and angle of advance from 250-300 and the expansion valve is driven by an eccentric having angle of advance 800-900.

6. The function of a reversing gear in a steam engine is
a) to control the supply of steam
b) to alter the point of cut-off while the engine is running
c) to reverse the direction of motion of the crank shaft
d) both b and c

View Answer

Answer: d [Reason:] The function of a reversing gear in a steam engine is to alter the point of cut-off while the engine is running and to reverse the direction of motion of the crank shaft.

7. When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a
a) D-slide valve
b) governor
c) Meyer’s expansion valve
d) flywheel

View Answer

Answer: b [Reason:] When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a governor. Flywheel controls the speed variation caused by the fluctuations of the engine turning moment during each cycle of operation.

8. A flywheel is used to control the mean speed of an engine caused by the variations in load.
a) True
b) False

View Answer

Answer: b [Reason:] The function of a governor is to regulate the mean speed of an engine caused by the variations in load.

9. Which of the following is used to control the speed variations of the engine caused by the fluctuations of the engine turning moment?
a) D-slide valve
b) Governor
c) Flywheel
d) Meyer’s expansion valve

View Answer

Answer: c [Reason:] The function of a governor is to regulate the mean speed of an engine caused by the variations in load. Flywheel controls the speed variation caused by the fluctuations of the engine turning moment during each cycle of operation.

Machine Design MCQ Set 3

1. The height of a Watt’s governor is equal to
a) 8.95/N2
b) 89.5/N2
c) 895/N2
d) 8950/N2

View Answer

Answer: c [Reason:] If N is the speed of the arm and ball about the spindle axis, then the height of the governor (h) is given by h = 895/N2 metres

2. The height of a Watt’s governor is
a) directly proportional to speed
b) directly proportional to (speed)
c) inversely proportional to speed
d) inversely proportional to (speed)

View Answer

Answer: d [Reason:] If N is the speed of the arm and ball about the spindle axis, then the height of the governor (h) is given by h = 895/N2 metres From this expression, we see that the height height of a Watt’s governor is inversely proportional to N2

3. A Watt’s governor can work satisfactorily at speeds from
a) 60 to 80 r.p.m
b) 80 to 100 r.p.m
c) 100 to 200 r.p.m
d) 200 to 300 r.p.m

View Answer

Answer: a [Reason:] A watt’s governor may only work satisfactorily at low speeds i.e. from 60 to 80 r.p.m.

4. The ratio of height of Porter governor to the height of Watt’s governor is
a) m/m + M
b) M/ m + M
c) m + M/m
d) m + M/M

View Answer

Answer: c [Reason:] The ratio of height of a Porter governor (when length of arms and links are equal) to the height of Watt’s governor is m + M/n, where m and M re the masses of the ball and sleeve respectively.

5. When the sleeve of a porter governor moves upwards, the governor speed
a) increases
b) decreases
c) remains unaffected
d) first increases and then decreases

View Answer

Answer: a [Reason:] When the sleeve of a porter governor moves upwards, the governor speed increases and when the sleeve moves downwards, the governor speed decreases.

6. When the sleeve of a Porter governor moves downwards, the governor speed
a) increases
b) decreases
c) remains unaffected
d) first increases and then decreases

View Answer

Answer: b [Reason:] When the sleeve of a porter governor moves upwards, the governor speed increases and when the sleeve moves downwards, the governor speed decreases.

7. In a Porter governor, the balls are attached to the extension of lower links.
a) True
b) False

View Answer

Answer: a [Reason:] Porter governor is a modification of Watt’s governor, with a central load attached to the sleeve.

8. A Hartnell governor is a
a) dead weight governor
b) pendulum type governor
c) spring loaded governor
d) inertia governor

View Answer

Answer: c [Reason:] A Hartnell governor is a spring loaded governor. Watt’s governor is a pendulum type governor.

9. A Watt’s governor is a spring loaded governor.
a) True
b) False

View Answer

Answer: b [Reason:] A Hartnell governor is a spring loaded governor. Watt’s governor is a pendulum type governor.

10. Which of the following is a pendulum type governor?
a) Watt’s governor
b) Porter governor
c) Hartnell governor
d) None of the mentioned

View Answer

Answer: a [Reason:] Watt’s governor is a pendulum type governor.

Machine Design MCQ Set 4

1. In vibration isolation system, if ω/ωn, then the phase difference between the transmitted force and the disturbing force is
a) 0°
b) 90°
c) 180°
d) 270°

View Answer

Answer: c [Reason:] In Vibration-isolation system, If the phase difference between transmitted force and the disturbing force is 180°C, then ω/ωn = 1.

2. 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

View Answer

Answer: b [Reason:] The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in transverse vibrations and the stress induced is bending stress.

3. 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

View Answer

Answer: a [Reason:] The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in transverse vibrations and the stress induced is bending stress.

4. In steady state forced vibrations, the amplitude of vibrations at resonance is _____________ damping coefficient.
a) equal to
b) directly proportional to
c) inversely proportional to
d) independent of

View Answer

Answer: c [Reason:] Forced vibration is when a time-varying disturbance (load, displacement or velocity) is applied to a mechanical system. The disturbance can be a periodic and steady-state input, a transient input, or a random input. The periodic input can be a harmonic or a non-harmonic disturbance.

5. 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

View Answer

Answer: c [Reason:] The vibrations of a body whose amplitude goes on reducing over every cycle of vibrations are known as damped vibrations. This is due to the fact that a certain amount of energy possessed by the vibrating body is always dissipated in overcoming frictional resistance to the motion.In these vibrations, the amplitude of the vibrations decreases exponentially due to damping forces like frictional force, viscous force, hysteresis etc.

6. 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

View Answer

Answer: c [Reason:] For underdamped systems the maximum amplitude of excitation has a definite value and it occurs at a frequency ω/ωn1. For damping factor, the transmissibility will be greater than unity.

7. 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

View Answer

Answer: c [Reason:] Natural frequency need to be equal to frequency of vibration so that resonance exists and it should show the indication of earthquake.

8. While calculating the natural frequency of a spring-mass system, the effect of the mass of the spring is accounted for by adding X times its value to the mass, where X is
a) 1/2
b) 1/3
c) 1/4
d) 3/4

View Answer

Answer: b [Reason:] Velocity at a distance “y” from fixed End = Velocity at free end /length of spring x y ∆k = 1/2 x M/3 x v2.

9. 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

View Answer

Answer: d [Reason:] Critical speed is expressed as natural frequency of the shaft.

10. 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

View Answer

Answer: a [Reason:] Frequency of automobile and road are same.

11. 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

View Answer

Answer: a [Reason:] We know natural frequency of a spring mass system is, ωn = √k/m ………..(i) This equation (i) does not depend on the g and weight (W = mg) So, the natural frequency of a spring mass system is unchanged on the moon. Hence, it will remain ωn , i.e. ωmoon = ωn.

12. 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

View Answer

Answer: a [Reason:] Given k = 3.6 kN/m, c = 400 Ns/m, m = 50 kg We know that, Natural Frequency ωn = √k/m = 8.485 rad/ sec And damping factor is given by, d = c/cc = c/2√km = 0.471

Damping Natural frequency, ωd = √1 – d2 ωn 2пfd = √1 – d2 ωn fd = 1.19 Hz.

13. 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

View Answer

Answer: c [Reason:] For an under damped harmonic oscillator resonance occurs when excitation frequency is equal to the undamped natural frequency ωd = ωn.

Machine Design MCQ Set 5

1. 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

View Answer

Answer: c [Reason:] When no external force acts on the body, after giving it an initial displacement, then the body is said to be under free or natural vibrations. The frequency of the free vibrations is called free or natural frequency. When there is a reduction in amplitude over every cycle of vibration, the motion is said to be damped vibration.

2. 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

View Answer

Answer: b [Reason:] When the particles of the shaft or disc moves parallel to the axis of the shaft, then the vibrations are known as longitudinal vibrations. When the particles of the shaft or disc move approximately perpendicular to the axis of the shaft, then the vibrations are known as transverse vibrations.

3. 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

View Answer

Answer: b [Reason:] In transverse vibrations,the shaft is straight and bent alternately and bending stresses are induced in the shaft.

4. 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

View Answer

Answer: d [Reason:] Natural Frequency, fn = 0.4985/δ where m = Mass of the body in kg, s = Stiffness of the body in N/m, and δ = Static deflection of the body in metres.

5. 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

View Answer

Answer: d [Reason:] To determine the critical speed of a shaft which may be subjected to point loads, uniformly distributed load or combination of both, we find the frequency of transverse vibration which is equal to critical speed of a shaft in r.p.s. The Dunkerley’s method may be used for calculating the frequency.

6. The equation of motion for a vibrating system with viscous damping is
d2x/dt2 + c/m X dx/dt + s/m X x = 0
If the roots of this equation are real, then the system will be
a) over damped
b) under damped
c) critically damped
d) none of the mentioned

View Answer

Answer: a [Reason:] When the roots are real, overdamping takes place. When the roots are complex conjugate underdamping takes place.

7. 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)

View Answer

Answer: b [Reason:] None

8. 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

View Answer

Answer: d [Reason:] Magnificiant Factor is the ratio of maximum displacement of the forced vibration (xmax) to the deflection due to the static force F(xo). Damping Factor is the ratio of amping coefficient for the actual system, and damping coefficient for the critical damped system.

9. In vibration isolation system, if ω/ωn is less than √2 , then for all values of the damping factor, the transmissibility will be
a) less than unity
b) equal to unity
c) greater than unity
d) zero
where ω = Circular frequency of the system in rad/s, and
ωn = Natural circular frequency of vibration of the system in rad/s.

View Answer

Answer: c [Reason:] The value of ω/ωn must be greater than √2 if ε is to be less than 1 and it is the numerical value of ε , independent of any phase difference between the forces that may exist which is important.

10. In vibration isolation system, if ω/ωn > 1, then the phase difference between the transmitted force and the disturbing force is
a) 0°
b) 90°
c) 180°
d) 270°

View Answer

Answer: c [Reason:] There is a phase difference of 180° between the transmitted force and the disturbing force.

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