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4

A disc is a spinning with an angular velocity ω rad/s about the axis of spin. The couple applied to the disc causing precession will be (where I = Mass moment of inertia of the disc, and ωP = Angular velocity of precession of the axis of spin)

A. (1/2).Iω²

B. Iω²

C. (1/2). I ω ωP

D. I ω ωP

Correct Answer :

D. I ω ωP


Related Questions

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4

The power of a Porter governor is equal to

A. [c²/(1 + 2c)] (m + M) g.h

B. [2c²/(1 + 2c)] (m + M) g.h

C. [3c²/(1 + 2c)] (m + M) g.h

D. [4c²/(1 + 2c)] (m + M) g.h

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4

To transmit power from one rotating shaft to another whose axes are neither parallel nor intersecting, use?

A. Spur gear

B. Spiral gear

C. Bevel gear

D. Worm gear

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4

The frictional torque transmitted in a flat pivot bearing with assumption of uniform pressure is _________ as compared to uniform wear.

A. Less

B. More

C. Same

D. None of these

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4

Which of the following is a higher pair?

A. Turning pair

B. Screw pair

C. Belt and pulley

D. None of the above

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4

A rotor supported at A and B carries two masses as shown in the below figure. The rotor is

A. Dynamically balanced

B. Statically balanced

C. Statically and dynamically balanced

D. Not balanced

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4

Which of the following would constitute a link?

A. Piston, piston rod and cross head

B. Piston and piston rod

C. Piston rod and cross head

D. Piston, crank pin and crank shaft

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4

Ball and a Socket forms a

A. Turning pair

B. Rolling pair

C. Screw pair

D. Spherical pair

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4

The acceleration of a particle moving with simple harmonic motion, at any instant is given by

A. ωx

B. ω²x

C. ω²/x

D. ω³/x

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4

The moment on the pulley which produces rotation is called

A. Inertia

B. Momentum

C. Moment of momentum

D. Torque

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4

For fluctuating loads, well suited bearing is

A. Ball bearing

B. Roller bearing

C. Needle roller bearing

D. Thrust bearing

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4

Which of the following is a spring controlled governor?

A. Hartnell governor

B. Hartung governor

C. Wilson-Hartnell governor

D. All of these

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4

The main disadvantage of the sliding pair is that it is

A. Bulky

B. Wears rapidly

C. Difficult to manufacture

D. Both (A) and (B) above

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4

The velocity of the rubbing surface __________ with the distance from the axis of the bearing.

A. Increases

B. Decreases

C. Remain same

D. None of these

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4

The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in

A. Transverse vibrations

B. Torsional vibrations

C. Longitudinal vibrations

D. All of these

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4

The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω₁ rad/s in the clockwise direction and the link OB turns with angular velocity ω₂ rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)

A. ω₁.ω₂.r

B. (ω₁ - ω₂)r

C. (ω₁ + ω₂)r

D. (ω₁ - ω₂)2r

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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

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

In a vibrating system, if the actual damping coefficient is 40 N/m/s and critical damping coefficient is 420 N/m/s, then logarithmic decrement is equal to

A. 0.2

B. 0.4

C. 0.6

D. 0.8

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4

In automobiles the power is transmitted from gear box to differential through

A. Bevel gear

B. Universal joint

C. Hooke's joint

D. Knuckle joint

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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 coupling rod of a locomotive, each of the four pairs is a ________ pair.

A. Sliding

B. Turning

C. Rolling

D. Screw

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4

In Meyer's expansion valve, the main valve is driven by an eccentric having an angle of advance from

A. 10°-15°

B. 15°-25°

C. 25°-30°

D. 30°-40°

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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

Under logarithmic decrement, the amplitude of successive vibrations are

A. Constant

B. In arithmetic progression

C. In geometric progression

D. In logarithmic progression

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4

The pitching of a ship produces forces on the bearings which act __________ to the motion of the ship.

A. Vertically and parallel

B. Vertically and perpendicular

C. Horizontally and parallel

D. Horizontally and perpendicular

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4

The relation between number of pairs (p) forming a kinematic chain and the number of links (l) is

A. l = 2p - 2

B. l = 2p - 3

C. l = 2p - 4

D. l = 2p - 5

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4

A circular bar moving in a round hole is an example of

A. Incompletely constrained motion

B. Partially constrained motion

C. Completely constrained motion

D. Successfully constrained motion

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4

Which of the following mechanism is an approximate straight line motion mechanism?

A. Watt's mechanism

B. Grasshopper mechanism

C. Robert's mechanism

D. All of these

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4

For high 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

A torsional system with discs of moment of inertia I₁ and I₂ as shown in the below figure, is gear driven such that the ratio of speed of shaft B to shaft A is 'G'. Neglecting the inertia of gears, the equivalent inertia of disc on shaft B at the speed of shaft A is equal to

A. G.I₂

B. G².I₂

C. I₂/G

D. I₂/G²