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4

Which is the false statement about the properties of instantaneous centre?

A. At the instantaneous center of rotation, one rigid link rotates instantaneously relative to another for the configuration of mechanism considered

B. The two rigid links have no linear velocities relative to each other at the instantaneous centre

C. The two rigid links which have no linear velocity relative to each other at this center have the same linear velocity to the third rigid link

D. The double centre can be denoted either by O2 or O12, but proper selection should be made

Correct Answer :

D. The double centre can be denoted either by O2 or O12, but proper selection should be made


Related Questions

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The absolute acceleration of any point P in a link about center of rotation O is

A. Along PO

B. Perpendicular to PO

C. At 45° to PO

D. None of the above

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4

The component of the acceleration, parallel to the velocity of the particle, at the given instant is called

A. Radial component

B. Tangential component

C. Coriolis component

D. None of these

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4

The velocity of a body moving with simple harmonic motion is __________ at the mean position.

A. Zero

B. Minimum

C. Maximum

D. None of these

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4

The ratio of maximum fluctuation of speed to the mean speed is called

A. Fluctuation of speed

B. Maximum fluctuation of speed

C. Coefficient of fluctuation of speed

D. None of these

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4

The unbalanced primary forces in a reciprocating engine are

A. Balanced completely

B. Balanced partially

C. Balanced by secondary forces

D. Not balanced

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4

A watt's governor can work satisfactorily at speeds from

A. 60 to 80 r.p.m.

B. 80 to 100 r.p.m.

C. 100 to 200 r.p.m.

D. 200 to 300 r.p.m.

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4

For low and moderate speed engines, the cam follower should move with

A. Uniform velocity

B. Simple harmonic motion

C. Uniform acceleration and retardation

D. Cycloidal motion

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4

The acceleration of a particle at any instant has two components i.e. radial component and tangential component. These two components will be

A. Parallel to each other

B. Perpendicular to each other

C. Inclined at 45°

D. Opposite to each other

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4

The approximate straight line mechanism is a

A. Four bar linkage

B. 6 bar linkage

C. 8 bar linkage

D. 3 bar linkage

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4

In a steam engine, the link constitutes a

A. Piston, piston rod and crosshead

B. Connecting rod with big and small end brasses, caps and bolts

C. Crank pin, crankshaft and flywheel

D. All of the above

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4

Transmission of power from the engine to the rear axle of an automobile is by means of

A. Compound gears

B. Worm and wheel method

C. Hooke's joint

D. Crown gear

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4

The velocity of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by (where ω = Angular velocity of the cam shaft)

A. ω (r₁ r₂) sinθ

B. ω (r₁ + r₂) sinθ sec2θ

C. ω (r₁ r₂) cosθ

D. ω (r₁ + r₂) cosθ cosec2θ

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4

When the nature of contact between the elements of a pair is such that it can only slide relative to the other, the pair is known as a

A. Screw pair

B. Spherical pair

C. Turning pair

D. Sliding pair

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4

The cam follower generally used in aircraft engines is

A. Knife edge follower

B. Flat faced follower

C. Spherical faced follower

D. Roller follower

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Which of the following is a turning pair?

A. Piston and cylinder of a reciprocating steam engine

B. Shaft with collars at both ends fitted into a circular hole

C. Lead screw of a lathe with nut

D. Ball and a socket joint

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4

The ratio of maximum fluctuation of energy to the workdone per cycle is called

A. Fluctuation of energy

B. Maximum fluctuation of energy

C. Coefficient of fluctuation of energy

D. None of these

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4

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

A. Increases

B. Decreases

C. Remain unaffected

D. First increases and then decreases

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4

Pitch point of a cam is

A. A point on the pitch curve having minimum pressure angle

B. A point on the pitch curve having maximum pressure angle

C. Any point on the pitch curve

D. Any point on the pitch circle

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4

When two pulleys are connected by means of a cross belt drive, then both the pulleys will rotate in __________ directions.

A. Same

B. Opposite

C. Perpendicular

D. None of these

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Kinematic pairs are those which have two elements that

A. Have line contact

B. Have surface contact

C. Permit relative motion

D. Are held together

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The relation between the controlling force (Fc) and radius of rotation (r) for a stable spring controlled governor is

A. Fc = ar + b

B. Fc = ar - b

C. Fc = ar

D. Fc = a/r + b

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4

The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as

A. Damping factor

B. Damping coefficient

C. Logarithmic decrement

D. Magnification factor

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Frequency of vibrations is usually expressed in

A. Number of cycles per hour

B. Number of cycles per minute

C. Number of cycles per second

D. None of these

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Open pairs are those which have

A. Point or line contact between the two elements when in motion

B. Surface contact between the two elements when in motion

C. Elements of pairs not held together mechanically

D. Two elements that permit relative motion

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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

The radial distance of a tooth from the pitch circle to the bottom of the tooth is called

A. Dedendum

B. Addendum

C. Clearance

D. Working depth

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4

Which of the following statement is correct as regard to the difference between a machine and a structure?

A. The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another

B. The links of a machine may transmit both power and motion, whereas the members of a structure transmit forces only

C. A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work

D. All of the above

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4

Which one of the following is an exact straight line mechanism using lower pairs?

A. Watts mechanism

B. Grasshopper mechanism

C. Roberts mechanism

D. Peaucelliers mechanism

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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

In a turning moment diagram, the variations of energy above and below the mean resisting torque line is called

A. Fluctuation of energy

B. Maximum fluctuation of energy

C. Coefficient of fluctuation of energy

D. None of these