Worksheetsdynamics of machines
Total questions: 40
Worksheet time: 20mins
The resonant frequency of a mass-spring system depends upon ________
a. stiffness
b. surface density
c. depth of air space
d. all of the above
Transmissibility is the ratio of ______
a. force transmitted to the supporting structure and force impressed upon the system
b. displacement amplitude of mass and displacement amplitude of supporting structure
c. both a. and b.
d. none of the above
What is the function of the controller in active vibration isolation systems?
a. Detect vibrations to be controlled
b. Reposition the masses
c. Interpret detected vibrations and execute commands
d. All of the above
Temperature monitoring technique uses which of the following devices to measure temperature of the machining surfaces?
a. Pyrometers
b. Thermocouples
c. Thermometers
d. All of the above
24) The motion of a system executing harmonic motion with one natural frequency is known as _______
a. principal mode of vibration
b. natural mode of vibration
c. both a. and b.
d. none of the above
When frequency ratio (ω/ωn) is greater than unity, phase angle decreases as _____
a. damping factor increases
b. damping factor decreases
c. both a. and b.
d. none of the above
According to D' Alembert's principle, m (d2x/ dt2) + c (dx/dt) + Kx =0 is the differential equation for damped free vibrations having single degree of freedom. What will be the solution to this differential equation if the system is critically damped?
a. x = (A + Bt) e– ωt
b. x = X e– ξωt (sin ωdt + Φ)
c. x = (A – Bt) e– ωt
d. x = X e– ξωt (cos ωdt + Φ)
Two springs have spring stiffness of 1500 N/m and 2000 N/m respectively. If they are connected in parallel, what is the equivalent spring stiffness
a. 3500 N/m
b. 1166 N/m
c. 857.63 N/m
d. None of the above
Which type of vibrations are also known as transient vibrations?
a. Undamped vibrations
b. Damped vibrations
c. Torsional vibrations
d. Transverse vibrations
42) During transverse vibrations, shaft is subjected to which type of stresses?
a. Tensile stresses
b. Torsional shear stress
c. Bending stresses
d. All of the above
Which of the following relations is true when springs are connected series?
where K = spring stiffness
a. Ke = K1 + K2
b. (1 / Ke) = (1/K1) + (1/ K2)
c. Ke = (1/K1) + (1/ K2)
d. None of the above
The unbalanced primary couple caused due to
reciprocating mass of each cylinder is given as
a. mrlω2 cos θ
b. mrlω (cos θ / n)
c. mrlω2 cos 2θ
d. mrω2 cos 2θ
Which of the following statements is/are true primary/secondary couple?
1. Secondary couple does not act on V engine
2. Primary couple acts on V engine
3. Secondary couple acts on reciprocating masses of multi-cylinder inline engines
4. Primary couple acts on reciprocating masses of multi-cylinder inline engines
a. 1 and 2
b. 2, 3 and 4
c. 1, 3 and 4
d. All of the above
46) Which of the following conditions should be satisfied for complete balancing of multi-cylinder inline engines?
a. Primary couples should be balanced
b. Secondary couples should be balanced
c. Both a. and b.
d. None of the above
At which angle primary unbalanced force in reciprocating engine mechanism is maximum?
a. 0o
b. 90o
c. 360o
d. All of the above
Secondary force in reciprocating engine mechanism is caused due to ______
a. S.H.M. of reciprocating parts
b. oscillation of reciprocating parts
c. obliquity of arrangement of reciprocating parts
d. all of the above
In the graph shown above, the region in which frequency ratio (ω/ωn) > √2 is known as___
a. Amplification region
b. Isolation region
c. Spring controlled region
d. None of the above
Which of the following statements is/are true?
a. Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction
b. Shaft vibrates with maximum frequency when rotors rotate in same direction
c. Zero node behavior is observed in rotors rotating in opposite direction
d. All of the above
In the diagram shown below, if rotor X and rotor Z rotate in same direction and rotor Y rotates in opposite direction, then specify the type of node vibration.
a. Three node vibration
b. Two node vibration
c. Single node vibration
d. None of the above
Magnification factor is the ratio of ______
a. zero frequency deflection and amplitude of steady state vibrations
b. amplitude of steady state vibrations and zero frequency deflection
c. amplitude of unsteady state vibrations and zero frequency distribution
d. none of the above
What is meant by phase difference or phase angle in forced vibrations?
a. Difference between displacement vector (xp) and velocity vector Vp
b. Angle in which displacement vector leads force vector by (F0 sinωt)
c. Angle in which displacement vector (xp) lags force vector (F0 sinωt)
d. None of the above
Which of the following statements is/are true?
1. Magnification factor is minimum at resonance
2. The maximum value of amplification factor increases as damping factor decreases
3. The maximum value of amplification factor increases as damping factor increases
4. Magnification factor is maximum at resonance
a. Statement 1 and statement 2
b. Statements 1,2 and 3
c. Statement 2 and statement 4
d. All the above statements are true
Which of the following factors are not responsible for unbalancing in rotating systems?
a. Errors
b. Tolerances
c. Shape of the rotor
d. None of the above
Which of the following conditions should be satisfied for static balancing?
1. Dynamic forces acting on the system should be zero
2. Couple acting on the system due to dynamic force should be zero
3. Centrifugal forces acting on the system should be zero
4. Couple acting on the system due to centrifugal forces should be zero
a. Condition 1 and condition 2
b. Condition 1 and condition 3
c. Condition 3 and condition 4
d. All of the above
δ = (W a2b2) / (3 EIl) is the value of deflection for ____
a. simply supported beam which has central point load
b. simply supported beam which has eccentric point load
c. simply supported beam which has U.D.L. point load per unit length
d. fixed beam which has central point load
Which among the following is the value of static deflection (δ) for a fixed beam with central point load?
a. (Wl3) /(192 EI)
b. (Wl2) /(192 EI)
c. (Wl3) /(384 EI)
d. None of the above
According to which method, maximum kinetic energy at mean position is equal to maximum potential energy at extreme position?
a. Energy method
b. Rayleigh's method
c. Equilibrium method
d. All of the above
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
Which of the following vibrations are classified according to magnitude of actuating force?
a. Torsional vibrations
b. Deterministic vibrations
c. Transverse vibrations
d. All of the above
In which type of vibrations, amplitude of vibration goes on decreasing every cycle?
a. Damped vibrations
b. Undamped vibrations
c. Both a. and b.
d. None of the above
87) What are discrete parameter systems?
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
Which among the following is the fundamental equation of S.H.M.?
a. x + (k / m) x =0
b. x + ω2x =0
c. x + (k/ m)2 x =0
d. x2 + ωx2 =0
The unbalanced force caused due to reciprocating mass is given by the equation
a. mrω2 sin θ + mrω2 (sin 2θ/n)
b. mrω2 sin θ + mrω2 (cos 2θ/n)
c. mrω2 cos θ + mrω2 (cos 2θ/n)
d. mrω2 (sin θ + sin 2θ/n)
Gyroscopic effect is not observed in which of the following actions performed by the ships?
a. Rolling
b. Pitching
c. Steering
d. All of the above
What is meant by pitching of ship?
a. up and down motion of bow and stern along transverse axis
b. up and down motion of bow and stern along longitudinal axis
c. up and down motion of port and starboard along transverse axis
d. none of the above
Degree of freedom for gyroscope rotor is
a. 1
b. 2
c. 3
d. 5
For a machine to be self-locking,its efficiency should be......
B.less than 67%
C.less than 50%
D.more than 50%
E.none of the above
A.100%
Hartnell governor couldbe classified under the head of.......
B.pendulum type governors
C.centrifugal type governors
D.dead weight type governors
E.none of the above
A.inertia type governors
Governor sensitivity is the ratio of.......
A.range of speed to the mean speed
B.maximum speed to the minimum speed
C.mean speed to the range of speed
D.effort of governor to the range of speed
E.governor lift to the range of speed
The quality of a governor can be judged by its......
A.stability
B.sensitivity
C.effort and power
D.none of the above
