Related Questions
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4
Efficiency of a screw jack is given by
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4
Consider the following mechanisms:
1. Oscillating cylinder engine mechanism
2. Toggle mechanism
3. Radial cylinder engine mechanism
4. Quick return mechanism Which of the above are inversions of slider crank mechanism?
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4
In an open pair, the two elements of a pair
A. Have a surface contact when in motion
B. Have a line or point contact when in motion
C. Are kept in contact by the action of external forces, when in motion
D. Are not held together mechanically
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4
In a screw jack, the effort required to lift the load W is given by (where α = Helix angle, and φ = Angle of friction)
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Two heavy rotating masses are connected by shafts of lengths l₁, l₂ and l₃ and the corresponding diameters are d₁, d₂ and d₃. This system is reduced to a torsionally equivalent system having uniform diameter d = d₁ of the shaft. The equivalent length of the shaft is
B. l = l₁ + l₂.(d₁/d₂)³ + l₂.(d₁/d₃)³
C. l = l₁ + l₂.(d₁/d₂)⁴ + l₃.(d₁/d₃)⁴
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4
Which of the following statement is wrong?
A. A round bar in a round hole form a turning pair
B. A square bar in a square hole form a sliding pair
C. A vertical shaft in a foot step bearing forms a successful constraint
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4
The condition for correct steering of a Davis steering gear is (where α = Angle of inclination of the links to the vertical)
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The magnitude of linear velocity of a point B on a link AB relative to point A is (Where ω = Angular velocity of the link AB)
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In a four-bar chain it is required to give an oscillatory motion to the follower for a continuous rotation of the crank. For the lengths of 50 mm of crank and 70 mm of the follower, determine theoretical maximum length of coupler. The minimum length of the coupler will be
B. Slightly less than 45 mm
C. Slightly more than 45 mm
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4
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
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The rotating shafts tend to vibrate violently at whirling speeds because
A. The system is unbalanced
B. Bearing centre line coincides with the axis
C. The shafts are rotating at very high speeds
D. Resonance is caused due to the heavy mass of the rotor
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4
Which of the following would constitute a link?
A. Piston, piston rod and cross head
C. Piston rod and cross head
D. Piston, crank pin and crank shaft
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4
In full depth involute system, the smallest number of teeth in a pinion which meshes with rack without interference is
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4
The cam follower generally used in aircraft engines is
C. Spherical faced follower
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The frictional torque transmitted in a truncated conical pivot bearing, considering uniform wear, is
A. (1/2). μ W cosec α (r₁ + r₂)
B. (2/3).μ W cosec α (r₁ + r₂)
C. (1/2). μ W cosec α [(r₁³ - r₂³)/(r₁² - r₂²)]
D. (2/3). μ W cosec α [(r₁³ - r₂³)/(r₁² - r₂²)]
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The ratio of height of Porter governor (when length of arms and links are equal) to the height of Watt's governor is (where m = Mass of the ball, and M = Mass on the sleeve)
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4
The example of completely constrained motion is a
A. Motion of a piston in the cylinder of a steam engine
B. Motion of a square bar in a square hole
C. Motion of a shaft with collars at each end in a circular hole
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4
The cam follower generally used in automobile engines is
C. Spherical faced follower
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The frequency of oscillation at compared to earth will be
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In a drag link quick return mechanism, the shortest link is always fixed. The sum of the shortest and longest link is
A. Equal to sum of other two
B. Greater than sum of other two
C. Less than sum of other two
D. There is no such relationship
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4
In a single slider crank chain
A. Each of the four pairs is a turning pair
B. One is a turning pair and three are sliding pairs
C. Two are turning pairs and two are sliding pairs
D. Three are turning pairs and one is a sliding pair
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The balancing weights are introduced in planes parallel to the plane of rotation of the disturbing mass. To obtain complete dynamic balance, the minimum number of balancing weights to be introduced in different planes is
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The radius of a friction circle for a shaft rotating inside a bearing is (where r = Radius of shaft, and tan φ = Coefficient of friction between the shaft and bearing)
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The distance by which the __________ of the D-slide valve overlaps the steam port is called exhaust lap.
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A cam mechanism imparts following motion
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A body in motion will be subjected to coriolis acceleration when that body is
A. In plane rotation with variable velocity
B. In plane translation with variable velocity
C. In plane motion which is a resultant of plane translation and rotation
D. Restrained to rotate while sliding over another body
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4
Sensitiveness of the governor is defined as the ratio of the
A. Mean speed to the maximum equilibrium speed
B. Mean speed to the minimum equilibrium speed
C. Difference of the maximum and minimum equilibrium speeds to the mean speed
D. Sum of the maximum and minimum equilibrium speeds to the mean speed
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3.The retardation of a flat faced follower when it has contact at the apex of the nose of a circular arc cam, is given by (where OQ = Distance between the centre of circular flank and centre of nose)
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In vibration isolation system, if ω/ωn > 1, then the phase difference between the transmitted force and the disturbing force is
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Which one of the following is an exact straight line mechanism using lower pairs?
D. Peaucelliers mechanism