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4

The static balancing is satisfactory for low speed rotors but with increasing speeds, dynamic balancing becomes necessary. This is because, the

A. Unbalanced couples are caused only at higher speeds

B. Unbalanced forces are not dangerous at higher speeds

C. Effects of unbalances are proportional to the square of the speed

D. Effects of unbalances are directly proportional to the speed

Correct Answer :

C. Effects of unbalances are proportional to the square of the speed


Related Questions

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4

Angle of ascent of cam is defined as the angle

A. During which the follower returns to its initial position

B. Of rotation of the cam for a definite displacement of the follower

C. Through which the cam rotates during the period in which the follower remains in highest position

D. Moved by the cam from the instant the follower begins to rise, till it reaches its highest position

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4

The contact ratio is given by

A. (Length of the path of approach)/(Circular pitch)

B. (Length of path of recess)/(Circular pitch)

C. (Length of the arc of contact)/(Circular pitch)

D. (Length of the arc of approach)/cosφ

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4

When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as a

A. Lower pair

B. Higher pair

C. Self-closed pair

D. Force-closed pair

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4

Which of the following disciplines provides study of inertia forces arising from the combined effect of the mass and the motion of the parts?

A. Theory of machines

B. Applied mechanics

C. Mechanisms

D. Kinetics

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4

In steady state forced vibrations, the amplitude of vibrations at resonance is __________ damping coefficient.

A. Equal to

B. Directly proportional to

C. Inversely proportional to

D. Independent of

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4

In S.H.M., acceleration is proportional to

A. Velocity

B. Displacement

C. Rate of change of velocity

D. All of the above

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4

A mechanism is an assemblage of

A. Two links

B. Three links

C. Four or more than four links

D. All of these

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4

The factional torque for square thread at the mean radius r while raising load W is given by

A. T = W.r tan(φ - α)

B. T = W.r tan(φ + α)

C. T = W.r tanα

D. T = W.r tanφ

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4

If the pressure angle is __________, a reciprocating follower will jam in its bearings.

A. Small

B. Too small

C. Large

D. Too large

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4

The cam follower generally used in automobile engines is

A. Knife edge follower

B. Flat faced follower

C. Spherical faced follower

D. Roller follower

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4

In a disc clutch, if there are n₁ number of discs on the driving shaft and n₂ number of discs on the driven shaft, then the number of pairs of contact surfaces will be

A. n₁ + n₂

B. n₁ + n₂ + 1

C. n₁ + n₂ - 1

D. n₁ + n₂ - 2

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4

If some links are connected such that motion between them can take place in more than one direction, it is called

A. Incompletely constrained motion

B. Partially constrained motion

C. Completely constrained motion

D. Successfully constrained motion

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4

A universal joint is an example of

A. Higher pair

B. Lower pair

C. Rolling pair

D. Sliding pair

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4

In railway axle boxes, the bearing used is

A. Deep groove ball bearing

B. Double row self aligning ball bearing

C. Double row spherical roller bearing

D. Cylindrical roller bearing

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4

In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where μ = Coefficient of friction between the blocks and the drum, θ = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)

A. T₁/T₂ = μ. θ. n

B. T₁/T₂ = [(1 - μ tanθ)/(1 + μ tanθ)]n

C. T₁/T₂ = (μ θ)n

D. T₁/T₂ = [(1 + μ tanθ)/(1 - μ tanθ)]n

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4

A friction circle is a circle drawn when a journal rotates in a bearing. Its radius depends upon the coefficient of friction and the

A. Magnitude of the forces on journal

B. Angular velocity of journal

C. Clearance between journal and bearing

D. Radius of journal

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4

Which gear train is used for higher velocity ratios in a small space?

A. Simple gear train

B. Compound gear train

C. Reverted gear train

D. Epicyclic gear train

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4

In a radial cam, the follower moves

A. In a direction perpendicular to the cam axis

B. In a direction parallel to the cam axis

C. In any direction irrespective of the cam axis

D. Along the cam axis

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4

In higher pair, the relative motion is

A. Purely turning

B. Purely sliding

C. Purely rotary

D. Combination of sliding and turning

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4

The working depth of a gear is the radial distance from the

A. Pitch circle to the bottom of a tooth

B. Pitch circle to the top of a tooth

C. Top of a tooth to the bottom of a tooth

D. Addendum circle to the clearance circle

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4

The partial balancing means

A. Balancing partially revolving masses

B. Balancing partially reciprocating masses

C. Best balancing of engines

D. All of these

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4

V-belts are usually used for

A. Long drives

B. Short drives

C. Long and short drives

D. None of these

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4

Coriolis component acts

A. Perpendicular to sliding surfaces

B. Along sliding surfaces

C. Somewhere in between above two

D. None of the above

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4

The sense of coriolis component 2 ωv is same as that of the relative velocity vector v rotated at

A. 45° in the direction of rotation of the link containing the path

B. 45° in the direction opposite to the rotation of the link containing the path

C. 90° in the direction of rotation of the link containing the path

D. 180° in the direction opposite to the rotation of the link containing the path

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4

When the sleeve of a Porter governor moves upwards, the governor speed

A. Increases

B. Decreases

C. Remain unaffected

D. First increases and then decreases

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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)

A. sinα = b/c

B. cosα = c/b

C. tanα = c/2b

D. cotα = c/2b

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4

When the elements of a pair are kept in contact by the action of external forces, the pair is said to be a

A. Lower pair

B. Higher pair

C. Self-closed pair

D. Force-closed pair

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4

The indicator using Watt mechanism is known as

A. Thompson indicator

B. Richard indicator

C. Simplex indicator

D. Thomson indicator

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4

A Hartnell governor is a

A. Dead weight governor

B. Pendulum type governor

C. Spring loaded governor

D. Inertia governor

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4

The dynamic friction is the friction experienced by a body, when the body

A. Is in motion

B. Is at rest

C. Just begins to slide over the surface of the other body

D. None of the above