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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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4

The velocity of a particle moving with simple harmonic motion, at any instant is given by (where ω = Displacement of the particle from mean position)

A. ω √(x² - r²)

B. ω √(r² - x²)

C. ω² √(x² - r²)

D. ω² √(r² - x²)

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4

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 type of gearing is used in steering system of an automobile?

A. Rack and pinion

B. Worm and wheel

C. Spiral gears

D. None of the above

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4

The amplitude of vibration is always __________ the radius of the circle.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

At the nodal point in a shaft, the amplitude for torsional vibration will be

A. Minimum

B. Maximum

C. Zero

D. Infinity

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4

Shaft revolving in a bearing is the following type of pair

A. Lower pair

B. Higher pair

C. Spherical pair

D. Cylindrical pair

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4

Which of the following disciplines provides study of the relative motion between the parts of a machine and the forces acting on the parts?

A. Theory of machines

B. Applied mechanics

C. Mechanisms

D. Kinetics

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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

A completely constrained motion can be transmitted with.

A. 1 link with pin joints

B. 2 links with pin joints

C. 3 links with pin joints

D. 4 links with pin joints

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4

The velocity of piston in a reciprocating steam engine is given by (where ω = Angular velocity of crank, r = Radius of crank pin circle, θ = Angle turned by crank from inner dead centre, and n = Ratio of length of connecting rod to the radius of crank)

A. ωr [sin θ + (sin 2θ/n)]

B. ωr [cos θ + (cos 2θ/n)]

C. ω²r [sin θ + (sin 2θ/n)]

D. ω²r [cos θ + (cos 2θ/n)]

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4

A slider crank chain consists of following numbers of turning and sliding pairs

A. 1, 3

B. 2, 2

C. 3, 1

D. 4, 0

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4

A combination of kinematic pairs, joined in such a way that the relative motion between the links is completely constrained, is called a

A. Structure

B. Mechanism

C. Kinematic chain

D. Inversion

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4

In order to balance the reciprocating masses,

A. Primary forces and couples must be balanced

B. Secondary forces and couples must be balanced

C. Both (A) and (B)

D. None of these

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4

The maximum efficiency of spiral gears is (where θ = Shaft angle, and φ = Friction angle)

A. sin (θ + φ) + 1/ cos (θ - φ) + 1

B. cos (θ - φ) + 1/ sin (θ + φ) + 1

C. cos (θ + φ) + 1/ cos (θ - φ) + 1

D. cos (θ - φ) + 1/ cos (θ + φ) + 1

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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

In a reciprocating steam engine, which of the following forms a kinematic link?

A. Cylinder and piston

B. Piston rod and connecting rod

C. Crankshaft and flywheel

D. Flywheel and engine frame

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4

Creep in belt drive is due to

A. Material of the pulley

B. Material of the belt

C. Larger size of the driver pulley

D. Uneven extensions and contractions due to varying tension

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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 Hooke's joint consists of:

A. Two forks

B. One fork

C. Three forks

D. Four forks

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4

The centre distance between two meshing involute gears is equal to

A. Sum of base circle radii/cosφ

B. Difference of base circle radii/ cosφ

C. Sum of pitch circle radii/ cosφ

D. Difference of pitch circle radii/ cosφ

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4

Which of the following statement is correct?

A. The primary unbalanced force is less than the secondary unbalanced force.

B. The primary unbalanced force is maximum twice in one revolution of the crank.

C. The unbalanced force due to reciprocating masses varies in magnitude and direction both.

D. The magnitude of swaying couple in locomotives is inversely proportional to the distance between the two cylinder centre lines

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4

Elements of pairs held together mechanically is known as

A. Closed pair

B. Open pair

C. Mechanical pair

D. Rolling pair

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4

The mechanism forms a structure, when the number of degrees of freedom (n) is equal to

A. 0

B. 1

C. 2

D. -1

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4

In gears, interference takes place when

A. The tip of a tooth of a mating gear digs into the portion between base and root circles

B. Gears do not move smoothly in the absence of lubrication

C. Pitch of the gears is not same

D. Gear teeth are undercut

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4

A point on a link connecting double slider crank chain traces a

A. Ellipse

B. Circle

C. Parabola

D. Hyperbola

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4

Kinematic 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

In a steam engine, one method of obtaining the earlier cut-off with a simple slide valve is by increasing the angle of advance of the eccentric while the throw of the eccentric, steam lap and exhaust lap are kept constant. This method will

A. Cause withdrawing or throttling of steam

B. Reduce length of effective stroke of piston

C. Reduce maximum opening of port to steam

D. All of these

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4

The maximum or minimum value of the swaying couple is

A. ± c.m.ω².r

B. ± a (1 - c) m.ω².r

C. ± (a/√2) (1 - c) m.ω².r

D. ± 2a (1 - c) m.ω².r

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4

The size of a gear is usually specified by

A. Pressure angle

B. Circular pitch

C. Diametral pitch

D. Pitch circle diameter

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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