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4

If ω/ωn is very low for a body vibrating under steady state vibrations, the phase angle for all values of damping factors, will tend to approach

A.

B. 90°

C. 180°

D. 360°

Correct Answer :

A. 0°


Related Questions

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4

The brake commonly used in railway trains is

A. Shoe brake

B. Band brake

C. Band and block brake

D. Internal expanding brake

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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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4

When the nature of contact between the elements of a pair is such that one element can turn about the other by screw threads, the pair is known as a

A. Screw pair

B. Spherical pair

C. Turning pair

D. Sliding pair

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4

The periodic time is given by (where ω = Angular velocity of the particle in rad/s)

A. ω/2π

B. 2π/ω

C. ω × 2π

D. π/ω

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4

A mass of 1 kg is attached to the end of a spring with a stiffness of 0.7 N/mm. The critical damping coefficient of this system is

A. 1.4 N-s/m

B. 18.52 N-s/m

C. 52.92 N-s/m

D. 529.2 N-s/m

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4

The displacement of a flat faced follower when it has contact with the flank of a circular arc cam, is given by (where R = Radius of flank, r₁ = Minimum radius of the cam, and θ = Angle turned through by the cam)

A. R (1 - cosθ)

B. (R - r₁) (1 - cosθ)

C. R (1 - sinθ)

D. (R - r₁) (1 - sinθ)

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4

The gear train usually employed in clocks is a

A. Simple gear train

B. Reverted gear train

C. Sun and planet gear

D. Differential gear

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4

When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a

A. D-slide valve

B. Governor

C. Meyer's expansion valve

D. Flywheel

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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 of the following is false statement in respect of differences between machine and structure?

A. Machines transmit mechanical work, whereas structures transmit forces

B. In machines, relative motion exists between its members, whereas same does not exist in case of structures

C. Machines modify movement and work, whereas structures modify forces

D. Efficiency of machines as well as structures is below 100%

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4

When the crank is at the inner dead centre, in a reciprocating steam engine, then the acceleration of the piston will be

A. ω²r. (n + 1)/n

B. ω²r. (n - 1)/n

C. ω²r. n/(n + 1)

D. ω²r. n/(n - 1)

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4

The direction of linear velocity of any point on a link with respect to another point on the same link is

A. Parallel to the link joining the points

B. Perpendicular to the link joining the points

C. At 45° to the link joining the points

D. None of the above

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4

A governor is said to be stable, if the

A. Radius of rotation of balls increases as the equilibrium speed decreases

B. Radius of rotation of balls decreases as the equilibrium speed decreases

C. Radius of rotation of balls increases as the equilibrium speed increases

D. Radius of rotation of balls decreases as the equilibrium speed increases

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4

When the relation between the controlling force (Fc) and radius of rotation (r) for a spring controlled governor is Fc = ar + b, then the governor will be

A. Stable

B. Unstable

C. Isochronous

D. None of these

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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

The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

A. Static friction

B. Dynamic friction

C. Limiting friction

D. Coefficient of friction

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4

The displacement of the reciprocating roller follower, when it has contact with the straight flanks of the tangent cam, is given by (where r₁ = Minimum radius of the cam, r₂ = Radius of the roller follower, and θ = Angle turned by the cam from the beginning of the follower displacement)

A. (r₁ - r₂) (1 - cosθ)

B. (r₁ + r₂) (1 + cosθ)

C. (r₁ - r₂) [(1 - cosθ)/cos θ]

D. (r₁ + r₂) [(1 - cosθ)/cos θ]

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4

When one of the links of a kinematic chain is fixed, the chain is known as a

A. Structure

B. Mechanism

C. Inversion

D. Machine

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4

A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by (where μ = tan φ = Coefficient of friction between the plane and the body)

A. P = W tan α

B. P = W tan (α + φ)

C. P = W (sin α + μ cos α)

D. P = W (cos α + μ sin α)

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4

Which of the following is a pendulum type governor?

A. Watt governor

B. Porter governor

C. Hartnell governor

D. None of these

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4

The example of successfully constrained motion is a

A. Motion of an I.C. engine valve

B. Motion of the shaft between a footstep bearing

C. Piston reciprocating inside an engine cylinder

D. All of the above

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4

If the rotating mass of a rim type flywheel is distributed on another rim type flywheel whose mean radius is half the mean radius of the former, then energy stored in the latter at the same speed will be

A. Four times the first one

B. Same as the first one

C. One fourth of the first one

D. One and a half times the first one

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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

In locomotives, the ratio of the connecting rod length to me crank radius is kept very large in order to

A. Minimise the effect of primary forces

B. Minimise the effect of secondary forces

C. Have perfect balancing

D. To start the locomotive quickly

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4

When a body is subjected to transverse vibrations, the stress induced in a body will be

A. Shear stress

B. Bending stress

C. Tensile stress

D. Compressive stress

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4

A chain comprises of 5 links having 5 joints. Is it kinematic chain?

A. Yes

B. No

C. It is a marginal case

D. Data are insufficient to determine it

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4

The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be

A. To dip the nose and tail

B. To raise the nose and tail

C. To raise the nose and dip the tail

D. To dip the nose and raise the tail

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4

The efficiency of a screw jack is maximum, when (where α = Helix angle, and φ = Angle of friction)

A. α = 45° + φ/2

B. α = 45° - φ/2

C. α = 90° + φ

D. α = 90° - φ

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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

Which of the following governor is used to drive a gramophone?

A. Watt governor

B. Porter governor

C. Pickering governor

D. Hartnell governor