When two pulleys of different diameters are connected by means of an open belt, the angle of contact at the ________ pulley must be taken into consideration.
Smaller
Larger
Either A or B
None of these
Correct Answer :
A. Smaller
Related Questions
Hart mechanism has
Eight links
Six links
Four links
Twelve links
Which of the following mechanism is obtained from lower pair?
Gyroscope
Pantograph
Valve and valve gears
All of the above
If ω/ωn = 2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will the
0.5
1
1.5
2
Creep in belt drive is due to
Weak material of the belt
Weak material of the pulley
Uneven extensions and contractions of the belt when it passes from tight side to slack side
Expansion of the belt
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
Which of the following statement is correct?
The primary unbalanced force is less than the secondary unbalanced force.
The primary unbalanced force is maximum twice in one revolution of the crank.
The unbalanced force due to reciprocating masses varies in magnitude and direction both.
The magnitude of swaying couple in locomotives is inversely proportional to the distance between the two cylinder centre lines
The natural frequency of free torsional vibrations of a shaft is equal to (where q = Torsional stiffness of the shaft, and I = Mass moment of inertia of the disc attached at the end of a shaft)
2π. √(q/I)
2π qI
(1/2π). √(q/I)
1/2π
The acceleration of a particle moving with simple harmonic motion, at any instant is given by
ωx
ω²x
ω²/x
ω³/x
The partial balancing of reciprocating parts in locomotives produces
Hammer blow
Swaying couple
Variation in tractive force along the line of stroke
All of the above
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
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is
5,367 r.p.m.
6,000 r.p.m.
9,360 r.p.m.
12,000 r.p.m.
For dynamic balancing of a shaft
The net dynamic force acting on the shaft is equal to zero
The net couple due to the dynamic forces acting on the shaft is equal to zero
Both (A) and (B)
None of the above
Rectangular bar in a rectangular hole is the following type of pair
Completely constrained motion
Partially constrained motion
Incompletely constrained motion
Freely constrained motion
Scotch yoke mechanism is used to generate
Sine functions
Square roots
Logarithms
Inversions
The sensitiveness of the governor __________ as the speed range decreases.
Remains unaffected
Decreases
Increases
None of these
The acceleration of a flat-faced follower when it has contact with the flank of a circular arc cam, is given by
ω² R cosθ
ω² (R - r₁) cosθ
ω² (R - r₁) sinθ
ω² r₁ sinθ
With usual notations for different parameters involved, the maximum fluctuations of energy for a flywheel is given by
2ECS
ECS/2
2ECS²
2E²CS
The locus of a point on a thread unwound from a cylinder will be
A straight line
A circle
Involute
Cycloidal
In a multiple V-belt drive, if one of the belts is broken, then we should replace
The broken belt only
All the belts
The broken belt and the belts on either side of it
None of the above
A mechanism is an assemblage of
Two links
Three links
Four or more than four links
All of these
When the speed of the engine fluctuates continuously above and below the mean speed, the governor is said to be
Stable
Unstable
Isochronous
Hunt
The relation between number of pairs (p) forming a kinematic chain and the number of links (l) is
l = 2p - 2
l = 2p - 3
l = 2p - 4
l = 2p - 5
Cross head and guides form a
Lower pair
Higher pair
Turning pair
Sliding pair
A mechanism __________ for transmitting or transforming motion.
Can be used
Cannot be used
Unpredictable
None of these
Transmission angle is the angle between
Input link and coupler
Input link and fixed link
Output link and coupler
Output link and fixed link
In multi V-belt transmission, if one of the belt is broken, we have to change the
Broken belt
Broken belt and its adjacent belts
All the belts
There is no need of changing any one as remaining belts can take care of transmission of load
An automobile steering gear is an example of
Sliding pair
Rolling pair
Lower pair
Higher pair
In a reciprocating steam engine, when the crank has turned from inner dead centre through an angle θ, the angular velocity of the connecting rod is given by
ω sinθ/(n² - sin²θ)1/2
ω cosθ/(n² - cos²θ)1/2
ω sinθ/(n² - cos²θ)1/2
ω cosθ/(n² - sin²θ)1/2
The magnitude of velocities of the points on a rigid link is
Directly proportional to the distance from the points to the instantaneous centre and is parallel to the line joining the point to the instantaneous centre
Directly proportional to the distance from the points to the instantaneous centre and is perpendicular to the line joining the point to the instantaneous centre
Inversely proportional to the distance from the points to the instantaneous centre and is parallel to the line joining the point to the instantaneous centre
Inversely proportional to the distance from the points to the instantaneous centre and is perpendicular to the line joining the point to the instantaneous centre
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