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This set of Dynamics of Machines Multiple Choice Questions & Answers (MCQs) focuses on Dynamics Of Machines Set 4
Q1 | The accelerometer is used as a transducer to measure earthquake in Richter scale. Its design is based on the principle that
- its natural frequency is very low in comparison to the frequency of vibration
- its natural frequency is very high in comparison to the frequency of vibration
- its natural frequency is equal to the frequency of vibration
- measurement of vibratory motion is without any reference point
Q2 | Critical speed is expressed as
- rotation of shaft in degrees
- rotation of shaft in radians
- rotation of shaft in minutes
- natural frequency of the shaft
Q3 | The first critical speed of an automobile running on a sinusoidal road is calculated by (modeling it as a single degree of freedom system)
- resonance
- approximation
- superposition
- rayleigh quotient
Q4 | 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
- ωn
- 0.408ωn
- 0.204ωn d) 0.167ωn
Q5 | 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
- 0.471 and 1.19 hz
- 0.471 and 7.48 hz
- 0.666 and 1.35 hz
- 0.666 and 8.50 hz
Q6 | 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
- 45
- 75
- 90
- 60
Q7 | 5 m/s.
- 4.19
- 5
- 3.49
- 3.36
Q8 | Which of the following expression represent the angular acceleration α of the connecting rod?
- −ω2 . sin θ/n
- −ω2 . cos θ.n
- ω2. cos θ/n
- ω2 . sin θ.n
Q9 | While calculating angular acceleration of the connecting rod, sin2(θ) term is neglected.
- true
- false
Q10 | 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.
- 10.3
- 11.1
- 12.2
- 11.8
Q11 | When a body is subjected to transverse vibrations, the stress induced in a body will be
- shear stress
- bending stress
- tensile stress
- compressive stress
Q12 | 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
- ωn
- 0.408ωn c) 0.204ωn d) 0.167ωn
Q13 | For an under damped harmonic oscillator, resonance
- occurs when excitation frequency is greater than undamped natural frequency
- occurs when excitation frequency is less than undamped natural frequency
- occurs when excitation frequency is equal to undamped natural frequency
- never occurs
Q14 | When there is a reduction in amplitude over every cycle of vibration, then the body is said to have
- free vibration
- forced vibration
- damped vibration
- none of the mentioned
Q15 | Longitudinal vibrations are said to occur when the particles of a body moves
- perpendicular to its axis
- parallel to its axis
- in a circle about its axis
- none of the mentioned
Q16 | When a body is subjected to transverse vibrations, the stress induced in a body will be
- shear stress
- tensile stress
- compressive stress
- none of the mentioned
Q17 | The natural frequency (in Hz) of free longitudinal vibrations is equal to
- 1/2π√s/m
- 1/2π√g/δ
- 0.4985/δ
- all of the mentioned
Q18 | The factor which affects the critical speed of a shaft is
- diameter of the disc
- span of the shaft
- eccentricity
- all of the mentioned
Q19 | 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
- x1/x2
- log (x1/x2)
- loge (x1/x2)
- log (x1.x2)
Q20 | The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as
- damping factor
- damping coefficient
- logarithmic decrement
- magnification factor
Q21 | Which of the following systems produce a vibration in the foundation?
- unbalanced machine
- balanced machine
- coupled machine
- uncoupled machine
Q22 | When a periodic disturbing force is applied to a machine, the force is transmitted to the foundation by the means of spring.
- true
- false
Q23 | Which of the following is correct regarding isolation factor?
- dimensionless quantity
- has newton as its unit
- has joule as its unit
- has hz as its unit
Q24 | Which of the following is a type of transmitted force to the foundation?
- damping force
- undamping force
- tensile force
- torsional force
Q25 | If isolation factor is negative, then what is the phase difference between transmitted and disturbing force?
- 180°
- 90°
- 450°
- 360°