Recent questions tagged mechanical-vibrations

Often an unbalance of forces is produced in rotary or reciprocating machinery due to the ______ * 1 point (A) Centripetal forces (B) Centrifugal forces (C) Friction forces (D) Inertia forces

Description : Often an unbalance of forces is produced in rotary or reciprocating machinery due to the ______ * 1 point (A) Centripetal forces (B) Centrifugal forces (C) Friction forces (D) Inertia forces

Last Answer : (D) Inertia forces

If the spring mass system with m and spring stiffness k is taken to very high altitude, the natural frequency of longitudinal vibrations * 1 point (A) increases (B) decreases (C) remain unchanged (D) may increase or decrease depending upon the value of the mass

Description : If the spring mass system with m and spring stiffness k is taken to very high altitude, the natural frequency of longitudinal vibrations * 1 point (A) increases (B) decreases (C) remain unchanged (D) may increase or decrease depending upon the value of the mass

Last Answer : (C) remain unchanged

The speed at which the shaft runs so that the additional deflection from the axis of rotation of the shaft becomes infinite, is known as _________ * 1 point (A) Whirling speed (B) Rotational speed (C) Stabilizing speed (D) Reciprocating speed

Description : The speed at which the shaft runs so that the additional deflection from the axis of rotation of the shaft becomes infinite, is known as _________ * 1 point (A) Whirling speed (B) Rotational speed (C) Stabilizing speed (D) Reciprocating speed

Last Answer : (A) Whirling speed

Frequency is equal to ______. * 1 point (A) time period (B) 1/time period (C) *time period (D) /time period

Description : Frequency is equal to ______. * 1 point (A) time period (B) 1/time period (C) *time period (D) /time period

Last Answer : (B) 1/time period

What are deterministic vibrations? * (A)Vibrations caused due to known exciting force (B)Vibrations caused due to unknown exciting force (c) Vibrations which are aperiodic in nature (D) None of the above

Description : What are deterministic vibrations? * (A)Vibrations caused due to known exciting force (B)Vibrations caused due to unknown exciting force (c) Vibrations which are aperiodic in nature (D) None of the above

Last Answer : (A)Vibrations caused due to known exciting force

Equilibrium Method is in accordance with which of the following principle? * 1 point (A) Taylor's principle (B) D'Alembert's principle (C) Energy conservation principle (D) None of the above

Description : Equilibrium Method is in accordance with which of the following principle? * 1 point (A) Taylor's principle (B) D'Alembert's principle (C) Energy conservation principle (D) None of the above

Last Answer : (B) D'Alembert's principle

According to which method, maximum kinetic energy at mean position is equal to maximum potential energy at extreme position? * 1 point (A) Energy method (B) Rayleigh's method (C) Equilibrium method (D) All of the above

Description : According to which method, maximum kinetic energy at mean position is equal to maximum potential energy at extreme position? * 1 point (A) Energy method (B) Rayleigh's method (C) Equilibrium method (D) All of the above

Last Answer : (B) Rayleigh's method

A mass of 1 kg is attached to two identical springs each with stiffness k = 20 kN/m as shown in the figure. Under frictionless condition, the natural frequency of the system in Hz is close to * 1 point (A) 32 (B) 23 (C) 16 (D) 11

Description : A mass of 1 kg is attached to two identical springs each with stiffness k = 20 kN/m as shown in the figure. Under frictionless condition, the natural frequency of the system in Hz is close to * 1 point (A) 32 (B) 23 (C) 16 (D) 11

Last Answer : (A) 32

What are discrete parameter systems? *1 point (A) Systems which have infinite number of degree of freedom (B) Systems which have finite number of degree of freedom (C) Systems which have no degree of freedom (D) None of the above

Description : What are discrete parameter systems? *1 point (A) Systems which have infinite number of degree of freedom (B) Systems which have finite number of degree of freedom (C) Systems which have no degree of freedom (D) None of the above

Last Answer : (B) Systems which have finite number of degree of freedom

What is meant by critical damping coefficient? * 1 point (A) Frequency of damped free vibrations is less than zero (B). The motion is a periodic in nature (C). Both a. and b. (D). None of the above

Description : What is meant by critical damping coefficient? * 1 point (A) Frequency of damped free vibrations is less than zero (B). The motion is a periodic in nature (C). Both a. and b. (D). None of the above

Last Answer : (C). Both a. and b.

The equivalent stiffness of spring connected in parallel having stiffnesses k1 and k2 can be written as * 1 point (A)(1/k1) + (1/k2) (B) (1/k1) - (1/k2) (C) k1 + k2 (D) None of the above

Description : The equivalent stiffness of spring connected in parallel having stiffnesses k1 and k2 can be written as * 1 point (A)(1/k1) + (1/k2) (B) (1/k1) - (1/k2) (C) k1 + k2 (D) None of the above

Last Answer : (C) k1 + k2

In damped vibrations, the amplitude of the resulting vibration gradually reduces. This is due to the reason that an amount of energy is always dissipated to overcome the ________ * 1 point (A) Frictional resistance (B) Work done(C) Fluid pressure (D) Air pressure

Description : In damped vibrations, the amplitude of the resulting vibration gradually reduces. This is due to the reason that an amount of energy is always dissipated to overcome the ________ * 1 point (A) Frictional resistance (B) Work done(C) Fluid pressure (D) Air pressure

Last Answer : (A) Frictional resistance

When the body vibrates under the influence of external force, then the body is said to be under ___________ . * 1 point (A) free vibrations (B) natural vibrations (C) forced vibrations (D) damped vibrations

Description : When the body vibrates under the influence of external force, then the body is said to be under ___________ . * 1 point (A) free vibrations (B) natural vibrations (C) forced vibrations (D) damped vibrations

Last Answer : (C) forced vibrations

When a rigid body is suspended vertically and it oscillates with a small amplitude under the action of the force of gravity, the body is known as * 1 point (A) simple pendulum (B) torsional pendulum (C) compound pendulum (D) second’s pendulum

Description : When a rigid body is suspended vertically and it oscillates with a small amplitude under the action of the force of gravity, the body is known as * 1 point (A) simple pendulum (B) torsional pendulum (C) compound pendulum (D) second’s pendulum

Last Answer : (C) compound pendulum

The natural frequency of a spring-mass system on earth is ωn. The natural frequency of this system on the moon (g of moon = g of earth /6) is * 1 point (A) ωn (B) 0.408ωn (C) 0.204ωn (D) 0.167ωn

Description : The natural frequency of a spring-mass system on earth is ωn. The natural frequency of this system on the moon (g of moon = g of earth /6) is * 1 point (A) ωn (B) 0.408ωn (C) 0.204ωn (D) 0.167ωn

Last Answer : (A) ωn

The vibration in a vehicle is normally expressed in the terms of the ______________. (A) displacement (B) velocity (C) acceleration (D) none of the above

Description : The vibration in a vehicle is normally expressed in the terms of the ______________. (A) displacement (B) velocity (C) acceleration (D) none of the above

Last Answer : (C) acceleration

. In centrifugal pendulum absorber , the natural frequency in cycle per second can be given by A Fn =N √(R/L) B Fn =1/N √(R/L) C Fn =N/2 √(R/L) D Fn =N2 √(R/L)

Description : . In centrifugal pendulum absorber , the natural frequency in cycle per second can be given by A Fn =N √(R/L) B Fn =1/N √(R/L) C Fn =N/2 √(R/L) D Fn =N2 √(R/L)

Last Answer : A Fn =N √(R/L)

In a two-rotor system, torsional vibration occurs only if the rotors are moving in the ______ direction. (A) same (B) opposite (C) either same or opposite (D) none of the above

Description : In a two-rotor system, torsional vibration occurs only if the rotors are moving in the ______ direction. (A) same (B) opposite (C) either same or opposite (D) none of the above

Last Answer : (B) opposite

Untuned viscous damper ( houdaille Damper) is used with variable speed machine being control by ratio can be given by A) (damper inertia) / (main system inertia) B) (main system inertia) / (damper inertia) C) (2 X damper inertia) / (main system inertia) D) (2 X main system inertia) / (damper inertia)

Description : Untuned viscous damper ( houdaille Damper) is used with variable speed machine being control by ratio can be given by A) (damper inertia) / (main system inertia) B) (main system inertia) / (damper inertia) ... X damper inertia) / (main system inertia) D) (2 X main system inertia) / (damper inertia)

Last Answer : A) (damper inertia) / (main system inertia)

In Fullarton Tachometer, a thin strip with a ______ is attached at one of its ends. (A) mass (B) spring (C) damper (D) shaft

Description : In Fullarton Tachometer, a thin strip with a ______ is attached at one of its ends. (A) mass (B) spring (C) damper (D) shaft

Last Answer : (A) mass

The accelerometers are commonly used in vibration measurement due to their ___________. (A) small size and low sensitivity (B) the large size and high sensitivity (C) the large size and low sensitivity (D) small size and high sensitivity

Description : The accelerometers are commonly used in vibration measurement due to their ___________. (A) small size and low sensitivity (B) the large size and high sensitivity (C) the large size and low sensitivity (D) small size and high sensitivity

Last Answer : (D) small size and high sensitivity

From the following, which one is also known as low-frequency Transducer? (A) Stroboscope (B) Accelerometer (C) Vibrometer (D) None of the above

Description : From the following, which one is also known as low-frequency Transducer? (A) Stroboscope (B) Accelerometer (C) Vibrometer (D) None of the above

Last Answer : (C) Vibrometer

A seismometer is a device used to measure the ___________ of a vibrating body. (A) displacement (B) velocity (C) acceleration (D) all of the above

Description : A seismometer is a device used to measure the ___________ of a vibrating body. (A) displacement (B) velocity (C) acceleration (D) all of the above

Last Answer : (A) displacement

Which of the following instruments measure the amplitude of a vibrating body? (A) Vibrometers (B) Seismometer (C) Both (a) and (b) (D) None of these

Description : Which of the following instruments measure the amplitude of a vibrating body? (A) Vibrometers (B) Seismometer (C) Both (a) and (b) (D) None of these

Last Answer : (C) Both (a) and (b)

Which of the following systems produce a vibration in the foundation? (A) Coupled machine(B) Uncoupled machine (C) Balanced machine (D) Unbalanced machine

Description : Which of the following systems produce a vibration in the foundation? (A) Coupled machine(B) Uncoupled machine (C) Balanced machine (D) Unbalanced machine

Last Answer : (D) Unbalanced machine

The speed at which the shaft runs so that the additional deflection of the shaft from the axis of rotation becomes ___________, is known as critical or whirling speed. (A) zero (B) minimum (C) maximum (D) infinite

Description : The speed at which the shaft runs so that the additional deflection of the shaft from the axis of rotation becomes ___________, is known as critical or whirling speed. (A) zero (B) minimum (C) maximum (D) infinite

Last Answer : (D) infinite

Unit of the damping factor is ______. (A) Nm/s (B) N/sm (C) N/m (D) none of the above

Description : Unit of the damping factor is ______. (A) Nm/s (B) N/sm (C) N/m (D) none of the above

Last Answer : (D) none of the above

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

Description : 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

Last Answer : (A) Damping force

From the following, which one is a type of vibration measuring instrument? A Mechanical B Electrical C Magnetic D All of the above

Description : From the following, which one is a type of vibration measuring instrument? A Mechanical B Electrical C Magnetic D All of the above

Last Answer : D All of the above

For a two-rotor system, the length of one shaft (A) is twice the other (B), then what is the relation between the mass moment of inertia of the shafts. A 2I(A) = I(B) B I(A) = 2I(B) C I(A) = I(B) D 2I(A) = 3I(B)

Description : For a two-rotor system, the length of one shaft (A) is twice the other (B), then what is the relation between the mass moment of inertia of the shafts. A 2I(A) = I(B) B I(A) = 2I(B) C I(A) = I(B) D 2I(A) = 3I(B)

Last Answer : A 2I(A) = I(B)

Magnification factor is the ratio of the maximum displacement due to forced vibrations to the deflection due to _______ A Static force B Dynamic force C Torsion D Compression

Description : Magnification factor is the ratio of the maximum displacement due to forced vibrations to the deflection due to _______ A Static force B Dynamic force C Torsion D Compression

Last Answer : A Static force

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°

Description : 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°

Last Answer : C 180°

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

Description : 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

Last Answer : C Occurs when excitation frequency is equal to undamped natural frequency

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

Description : 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

Last Answer : A Resonance

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

Description : 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

Last Answer : D natural frequency of the shaft

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

Description : 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 ... is equal to the frequency of vibration D Measurement of vibratory motion is without any reference point

Last Answer : C Its natural frequency is equal to the frequency of vibration

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

Description : 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

Last Answer : C greater than unity

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

Description : 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

Last Answer : C inversely proportional to

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

Description : 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

Last Answer : A Transverse vibrations

When the torsional pendulum vibrating the observed amplitudes on the same side of neutral axis for successive cycles are found to decay 50% of the initial value determine logarithmic decrement. A 0.065 B 0.006 C 0.693 D 0.5

Description : When the torsional pendulum vibrating the observed amplitudes on the same side of neutral axis for successive cycles are found to decay 50% of the initial value determine logarithmic decrement. A 0.065 B 0.006 C 0.693 D 0.5

Last Answer : C 0.693

A simple pendulum is found to vibrate at a frequency of 0.5Hz in vacuum and0.45 Hz in a viscous fluid medium. Find the damping factor. 0.5122 (B) 0.9272 (C) 0.4359 (D) 0.2568

Description : A simple pendulum is found to vibrate at a frequency of 0.5Hz in vacuum and0.45 Hz in a viscous fluid medium. Find the damping factor. 0.5122 (B) 0.9272 (C) 0.4359 (D) 0.2568

Last Answer : (C) 0.4359

The static deflection of a spring under gravity, when a mass of 1 kg is suspended from it, is 1 mm. Assume the acceleration due to gravity g = 10 m/s^2. The natural frequency of this spring-mass system (in rad/s) is A 100 B 150 C 200 D 250

Description : The static deflection of a spring under gravity, when a mass of 1 kg is suspended from it, is 1 mm. Assume the acceleration due to gravity g = 10 m/s^2. The natural frequency of this spring-mass system (in rad/s) is A 100 B 150 C 200 D 250

Last Answer : A 100

A cantilever shaft having 50 mm diameter and a length of 300mm has a disc of mass 100 kg at its free end. The Young’s modulus for the shaft material is 200 GN/m^2. Determine the static deflection of shaft in mm. A 0.144 B 0.244 C 0.344 D 0.444

Description : A cantilever shaft having 50 mm diameter and a length of 300mm has a disc of mass 100 kg at its free end. The Young’s modulus for the shaft material is 200 GN/m^2. Determine the static deflection of shaft in mm. A 0.144 B 0.244 C 0.344 D 0.444

Last Answer : A 0.144

A vehicle suspension system consists of a spring and a damper. Stiffness of spring is 3.5 KN/m and damping constant of damper is 400Ns/m. If mass is 50 kg, then damping factor is A 0.606 B 0.10 C 0.666 D 0.471

Description : A vehicle suspension system consists of a spring and a damper. Stiffness of spring is 3.5 KN/m and damping constant of damper is 400Ns/m. If mass is 50 kg, then damping factor is A 0.606 B 0.10 C 0.666 D 0.471

Last Answer : D 0.471

Rotor shaft of a large electric motor supported between short bearings at both ends shows a deflection of 1.8 mm in middle of motor. Assuming rotor to be perfectly balanced and supported at knife edges at both ends, likely critical speed (rpm) of shaft isA 350 B 4430 C 705 D 2810

Description : Rotor shaft of a large electric motor supported between short bearings at both ends shows a deflection of 1.8 mm in middle of motor. Assuming rotor to be perfectly balanced and supported at knife edges at both ends, likely critical speed (rpm) of shaft isA 350 B 4430 C 705 D 2810

Last Answer : C 705

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

Description : 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

Last Answer : D Magnification factor

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

Description : 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

Last Answer : C Damped vibration

The ratio of the actual damping coefficient (c) to the critical damping coefficient (cc ) is known as _________ A Damping factor B Damping coefficient C Resistive factor D Resistive coefficient

Description : The ratio of the actual damping coefficient (c) to the critical damping coefficient (cc ) is known as _________ A Damping factor B Damping coefficient C Resistive factor D Resistive coefficient

Last Answer : A Damping factor

Calculate logarithmic decrement if damping factor is 0.33. A 1.36 B 3.23 C 5.16D 2.19

Description : Calculate logarithmic decrement if damping factor is 0.33. A 1.36 B 3.23 C 5.16D 2.19

Last Answer : D 2.19

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