The critical speed of a shaft depends upon its
Mass
Stiffness
Mass and stiffness
Stiffness and eccentricity
Correct Answer :
C. Mass and stiffness
Related Questions
The C.G. of a link in any mechanism would experience
No acceleration
Linear acceleration
Angular acceleration
Both angular and linear accelerations
When a point moves along a straight line, its acceleration will have
Radial component only
Tangential component only
Coriolis component only
Radial and tangential components both
In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be (where ω = Angular speed of the system, ωn = Natural frequency of vibration of the system)
Less than unity
Equal to unity
Greater than unity
Zero
The velocity of the belt for maximum power is (where m = Mass of the belt in kg per metre length)
T/3
(T.g)/3
√(T/3m)
√(3m/T)
Which of the following is an open pair?
Ball and socket joint
Journal bearing
Lead screw and nut
Cam and follower
The power of a Porter governor is equal to
[c²/(1 + 2c)] (m + M) g.h
[2c²/(1 + 2c)] (m + M) g.h
[3c²/(1 + 2c)] (m + M) g.h
[4c²/(1 + 2c)] (m + M) g.h
The coriolis component of acceleration depends upon
Velocity of slider
Angular velocity of the link
Both (A) and (B)
None of these
A mass of 1 kg is attached to the end of a spring with a stiffness of 0.7 N/mm. The critical damping coefficient of this system is
1.4 N-s/m
18.52 N-s/m
52.92 N-s/m
529.2 N-s/m
The lead screw of a lathe with nut forms a
Rolling pair
Sliding pair
Screw pair
Turning pair
The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke (θ) is equal to
90° and 180°
45° and 225°
180° and 270°
270° and 360°
The example of rolling pair is
Bolt and nut
Lead screw of a lathe
Ball and socket joint
Ball bearing and roller bearing
The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is
0° and 90°
0° and 180°
90° and 180°
180° and 360°
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
The example of lower pair is
Shaft revolving in a bearing
Straight line motion mechanisms
Automobile steering gear
All of the above
Which of the following statement is correct?
The power absorbed in operating the piston valve is less than D-slide valve
The wear of the piston valve is less than the wear of the D-slide valve
The D-slide valve is also called outside admission valve.
All of the above
With usual notations for different parameters involved, the maximum fluctuations of energy for a flywheel is given by
2ECS
ECS/2
2ECS²
2E²CS
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
The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
12
14
18
24
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
Which of the following disciplines provides study of inertia forces arising from the combined effect of the mass and the motion of the parts?
Theory of machines
Applied mechanics
Mechanisms
Kinetics
The secondary unbalanced force is maximum __________ in one revolution of the crank.
Two times
Four times
Eight times
Sixteen times
Which one of the following is an exact straight line mechanism using lower pairs?
Watts mechanism
Grasshopper mechanism
Roberts mechanism
Peaucelliers mechanism
The balancing of a rigid rotor can be achieved by appropriately placing balancing masses in
A single plane
Two planes
Three planes
Four planes
A shaft carrying two rotors at its ends will have
No node
One node
Two nodes
Three nodes
In Meyer's expansion valve, the expansion valve is driven by an eccentric having an angle of advance from
50°-60°
60°-70°
70°-80°
80°-90°
Hammer blow
Is the maximum horizontal unbalanced force caused by the mass provided to balance the reciprocating masses.
Is the maximum vertical unbalanced force caused by the mass added to balance the reciprocating masses
Varies as the square root of the speed
Varies inversely with the square of the speed
The rotating shafts tend to vibrate violently at whirling speeds because
The system is unbalanced
Bearing centre line coincides with the axis
The shafts are rotating at very high speeds
Resonance is caused due to the heavy mass of the rotor
When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be
To move the ship towards starboard
To move the ship towards port side
To raise the bow and lower the stern
To raise the stern and lower the bow
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)
Critical damping is a function of
Mass and stiffness
Mass and damping coefficient
Mass and natural frequency
Damping coefficient and natural frequency