A body is said to be under forced vibrations, when
There is a reduction in amplitude after every cycle of vibration
No external force acts on a body, after giving it an initial displacement
A body vibrates under the influence of external force
None of the above
Correct Answer :
A. There is a reduction in amplitude after every cycle of vibration
Related Questions
The minimum periodic time of a compound pendulum is
(1/2π). √(kG/g)
(1/2π). √(2kG/g)
2π. √(kG/g)
2π. √(2kG/g)
The example of lower pair is
Shaft revolving in a bearing
Straight line motion mechanisms
Automobile steering gear
All of the above
The unbalanced primary forces in a reciprocating engine are
Balanced completely
Balanced partially
Balanced by secondary forces
Not balanced
For simple harmonic motion of the of follower, a cosine curve represents
Displacement diagram
Velocity diagram
Acceleration diagram
All of the above
A torsional system with discs of moment of inertia I₁ and I₂ as shown in the below figure, is gear driven such that the ratio of speed of shaft B to shaft A is 'G'. Neglecting the inertia of gears, the equivalent inertia of disc on shaft B at the speed of shaft A is equal to 
G.I₂
G².I₂
I₂/G
I₂/G²
Effort of a governor is the
Mean force exerted at the sleeve for a given percentage change of speed
Workdone at the sleeve for maximum equilibrium speed
Mean force exerted at the sleeve for maximum equilibrium speed
None of the above
The displacement of the reciprocating roller follower, when it has contact with the straight flanks of the tangent cam, is given by (where r₁ = Minimum radius of the cam, r₂ = Radius of the roller follower, and θ = Angle turned by the cam from the beginning of the follower displacement)
(r₁ - r₂) (1 - cosθ)
(r₁ + r₂) (1 + cosθ)
(r₁ - r₂) [(1 - cosθ)/cos θ]
(r₁ + r₂) [(1 - cosθ)/cos θ]
In a multiple V-belt drive, when a single belt is damaged, it is preferable to change the complete set to
Reduce vibration
Reduce slip
Ensure uniform loading
Ensure proper alignment
Angle of ascent of cam is defined as the angle
During which the follower returns to its initial position
Of rotation of the cam for a definite displacement of the follower
Through which the cam rotates during the period in which the follower remains in highest position
Moved by the cam from the instant the follower begins to rise, till it reaches its highest position
Under logarithmic decrement, the amplitude of successive vibrations are
Constant
In arithmetic progression
In geometric progression
In logarithmic progression
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 these
The Klein's method of construction for reciprocating engine mechanism
Is a simplified version of instantaneous centre method
Utilises a quadrilateral similar to the diagram of mechanism for reciprocating engine
Enables determination of coriolis component
Is based on the acceleration diagram
When the elements of a pair are kept in contact by the action of external forces, the pair is said to be a
Lower pair
Higher pair
Self-closed pair
Force-closed pair
The mechanism consisting of three turning pairs and one sliding pair, is called a
Single slider crank chain
Whitworth quick return motion mechanism
Crank and slotted lever quick return motion mechanism
All of the above
The pitching of a ship produces forces on the bearings which act __________ to the motion of the ship.
Vertically and parallel
Vertically and perpendicular
Horizontally and parallel
Horizontally and perpendicular
In under damped vibrating system, the amplitude of vibration
Decreases linearly with time
Increases linearly with time
Decreases exponentially with time
Increases exponentially with time
In the two rotor system as shown in the below figure (I₁ < I₂), a node of vibration is situated 
Between I₁, and I₂ but nearer I₁
Between I₁, and I₂ but nearer to I₂
Exactly in the middle of the shaft
Nearer to I₁ but outside
For high speed engines, the cam follower should move with
Uniform velocity
Simple harmonic motion
Uniform acceleration and retardation
Cycloidal motion
When the axes of the first and last wheels are coaxial, then the train is known as
Simple train of wheels
Compound train of wheels
Reverted gear train
Epicyclic gear train
Which of the following statement is wrong?
A round bar in a round hole form a turning pair
A square bar in a square hole form a sliding pair
A vertical shaft in a foot step bearing forms a successful constraint
All of the above
The centre distance between two meshing involute gears is equal to
Sum of base circle radii/cosφ
Difference of base circle radii/ cosφ
Sum of pitch circle radii/ cosφ
Difference of pitch circle radii/ cosφ
Which of the following mechanism is an approximate straight line motion mechanism?
Watt's mechanism
Grasshopper mechanism
Robert's mechanism
All of these
Governor is used in automobile to
Decrease the variation of speed
Maximize the fuel economy
Limit the vehicle speed
Maintain constant engine speed
In a pantograph, all the pairs are
Turning pairs
Sliding pairs
Spherical pairs
Self-closed pairs
Klein's construction gives a graphic construction for
Slider-crank mechanism
Velocity polygon
Acceleration polygon
Four bar chain mechanism
Which of the following disciplines provides study of the relative motion between the parts of a machine and the forces acting on the parts?
Theory of machines
Applied mechanics
Mechanisms
Kinetics
In order to balance the reciprocating masses,
Primary forces and couples must be balanced
Secondary forces and couples must be balanced
Both (A) and (B)
None of these
The critical speed of a shaft in revolution per second is __________ as that of natural frequency of transverse vibration.
Same
Different
Unpredictable
None of these
Two pulleys of radii r₁ and r₂ and at distance x apart are connected by means of an open belt drive. The length of the belt is
π (r₁ + r₂) + (r₁ + r₂)²/x + 2x
π (r₁ + r₂) + (r₁ - r₂)²/x + 2x
π (r₁ - r₂) + (r₁ - r₂)²/x + 2x
π (r₁ - r₂) + (r₁ + r₂)²/x + 2x
The gear train usually employed in clocks is a
Simple gear train
Reverted gear train
Sun and planet gear
Differential gear