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4

A Hartnell governor has its controlling force (Fc) given by Fc = ar + b, where r is the radius of rotation and a and b are constants. The governor becomes isochronous when

A. a is +ve and b = 0

B. a = 0 and b is +ve

C. a is +ve and b is -ve

D. a is +ve and b is also +ve

Correct Answer :

A. a is +ve and b = 0


Related Questions

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4

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 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

In full depth involute system, the smallest number of teeth in a pinion which meshes with rack without interference is

A. 12

B. 16

C. 25

D. 32

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4

When brakes are applied to all the four wheels of a moving car, the distance travelled by the car before it is brought to rest, will be

A. Maximum

B. Minimum

C. Zero

D. None of these

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4

Sense of tangential acceleration of a link

A. Is same as that of velocity

B. Is opposite to that of velocity

C. Could be either same or opposite to velocity

D. Is perpendicular to that of velocity

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4

The contact ratio is the ratio of

A. Length of pair of contact to the circular pitch

B. Length of arc of contact to the circular pitch

C. Length of arc of approach to the circular pitch

D. Length of arc of recess to the circular pitch

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4

In a simple harmonic motion, the velocity vector with respect to displacement vector

A. Is in phase

B. Leads by 90°

C. Leads by 180°

D. Lags by 90°

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4

The face of the tooth is the

A. Surface of the top of tooth

B. Surface of tooth above the pitch surface

C. Width of tooth below the pitch surface

D. Width of tooth measured along the pitch circle

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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

When a point moves along a straight line, its acceleration will have

A. Radial component only

B. Tangential component only

C. Coriolis component only

D. Radial and tangential components both

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4

The periodic time of a compound pendulum is __________ when the distance between the point of suspension and the centre of gravity is equal to the radius of gyration of the body about its centre of gravity.

A. Zero

B. Minimum

C. Maximum

D. None of these

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4

Klein's construction can be used when

A. Crank has a uniform angular velocity

B. Crank has non-uniform velocity

C. Crank has uniform angular acceleration

D. Crank has uniform angular velocity and angular acceleration

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4

The equation of free vibrations of a system is (d²x/dt²) +36 π²x, its natural frequency is

A. 3 Hz

B. 3π Hz

C. 6 Hz

D. 6π Hz

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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

The size of cam depends upon

A. Base circle

B. Pitch circle

C. Prime circle

D. Pitch curve

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4

In a cam drive with uniform velocity follower, the sharp corners of the displacement diagram are rounded off at the beginning and at the end of each stroke. This is done

A. Because of difficulty in manufacturing cam profile

B. Because of loose contact of follower with cam surface

C. In order to have acceleration in beginning and retardation at the end of stroke within the finite limits

D. Because the uniform velocity motion is a partial parabolic motion

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4

The Ackermann steering mechanism is preferred to the Davis type in automobiles because

A. The former is mathematically accurate

B. The former is having turning pair

C. The former is most economical

D. The former is most rigid

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4

The coriolis component of acceleration exists whenever a point moves along a path that has

A. Linear displacement

B. Rotational motion

C. Gravitational acceleration

D. Tangential acceleration

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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

A spring controlled governor is said to be isochronous when the controlling force

A. Increases as the radius of rotation decreases

B. Increases as the radius of rotation increases

C. Decreases as the radius of rotation increases

D. Remain constant for all radii of rotation

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4

The gears are termed as medium velocity gears, if their peripheral velocity is

A. 1-3 m/s

B. 3-15 m/s

C. 15-30 m/s

D. 30-50 m/s

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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

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4

The maximum fluctuation of speed is the

A. Difference of minimum fluctuation of speed and the mean speed

B. Difference of the maximum and minimum speeds

C. Sum of maximum and minimum speeds

D. Variations of speed above and below the mean resisting torque line

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4

If the number of links in a mechanism is equal to l, then the numbers of possible inversions are equal to

A. l - 2

B. l - 1

C. l

D. l + 1

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4

With single Hooke's joint it is possible to connect two shafts, the axes of which have an angular misalignment up to

A. 10°

B. 20°

C. 30°

D. 40°

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4

In order to give a complete secondary balance of a multi-cylinder inline engine,

A. The algebraic sum of the secondary forces must be equal to zero

B. The algebraic sum of the couples about any point in the plane of the secondary forces must be equal to zero

C. Both (A) and (B)

D. None of these

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4

The instantaneous centres which vary with the configuration of mechanism are called

A. Permanent instantaneous centres

B. Fixed instantaneous centres

C. Neither fixed nor permanent instantaneous centres

D. None of the above

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4

Two pulleys of radii r₁ and r₂ and at distance x apart are connected by means of an open belt drive. The length of the belt is

A. π (r₁ + r₂) + (r₁ + r₂)²/x + 2x

B. π (r₁ + r₂) + (r₁ - r₂)²/x + 2x

C. π (r₁ - r₂) + (r₁ - r₂)²/x + 2x

D. π (r₁ - r₂) + (r₁ + r₂)²/x + 2x

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4

The danger of breakage and vibration is maximum

A. Below the critical speed

B. Near the critical speed

C. Above the critical speed

D. None 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