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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

Correct Answer :

C. Neither fixed nor permanent instantaneous centres


Related Questions

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4

The length of a simple pendulum which gives the same frequency as the compound pendulum, is

A. kG + l₁

B. kG² + l₁

C. (kG² + l₁²)/ l₁

D. (kG + l₁²)/ l₁

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4

The minimum force required to slide a body of weight W on a rough horizontal plane is

A. W sinθ

B. W cosθ

C. W tanθ

D. W cosecθ

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4

The secondary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, θ = Angle of inclination of crank with the line of stroke, and n = Ratio of the length of connecting rod to radius of crank)

A. m.ω².r sinθ

B. m.ω².r cosθ

C. m.ω².r (sin 2θ/n)

D. m.ω².r (cos 2θ/n)

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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

The contact ratio is given by

A. (Length of the path of approach)/(Circular pitch)

B. (Length of path of recess)/(Circular pitch)

C. (Length of the arc of contact)/(Circular pitch)

D. (Length of the arc of approach)/cosφ

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4

The coriolis component of acceleration depends upon

A. Velocity of slider

B. Angular velocity of the link

C. Both (A) and (B)

D. None of these

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4

In order to give the primary balance of the reciprocating parts of a multi-cylinder inline engines,

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

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

C. Both (A) and (B)

D. None of these

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4

Sensitiveness of the governor is defined as the ratio of the

A. Mean speed to the maximum equilibrium speed

B. Mean speed to the minimum equilibrium speed

C. Difference of the maximum and minimum equilibrium speeds to the mean speed

D. Sum of the maximum and minimum equilibrium speeds to the mean speed

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4

In a screw jack, the effort required to lower the load W is given by

A. P = W tan(α - φ)

B. P = W tan(α + φ)

C. P = W tan(φ - α)

D. P = W cos(α + φ)

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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

Typewriter constitutes

A. Machine

B. Structure

C. Mechanism

D. Inversion

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4

In the below figure, PC is the connecting rod and OC is the crank making an angle θ with the line of stroke PO and rotates with uniform angular velocity at ω rad/s. The Klien's acceleration diagram for determining the acceleration of the piston P is shown by quadrilateral CQNO, if N coincides with O, then

A. Acceleration and velocity of the piston P is zero

B. Acceleration and velocity of the piston P is maximum

C. Acceleration of the piston P is zero and its velocity is maximum

D. Acceleration of the piston P is maximum and its velocity is zero

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4

The purpose of a link is to

A. Transmit motion

B. Guide other links

C. Act as a support

D. All of the above

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4

Cam size depends upon

A. Base circle

B. Pitch circle

C. Prime circle

D. Outer circle

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4

The dynamic friction is the friction experienced by a body, when the body

A. Is in motion

B. Is at rest

C. Just begins to slide over the surface of the other body

D. None of the above

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4

In a Hartnell governor, the stiffness of the spring is given by (where S1 and S2 = Spring forces exerted on the sleeve at max. and min. radii of rotation, and h = Compression of the spring)

A. (S₁ + S₂)/h

B. (S₁ - S₂)/h

C. (S₁ + S₂)/2h

D. (S₁ - S₂)/2h

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4

Flexible coupling is used because

A. It is easy to disassemble

B. It is easy to engage and disengage

C. It transmits shocks gradually

D. It prevents shock transmission and eliminates stress reversals

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4

The product of the diametral pitch and circular pitch is equal to

A. 1

B. 1/π

C. π

D. 2 π

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4

Effort of a governor is the

A. Mean force exerted at the sleeve for a given percentage change of speed

B. Workdone at the sleeve for maximum equilibrium speed

C. Mean force exerted at the sleeve for maximum equilibrium speed

D. None of the above

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4

The method of direct and reverse cranks is used in engines for

A. The control of speed fluctuations

B. Balancing of forces and couples

C. Kinematic analysis

D. Vibration analysis

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4

A body is said to be under forced vibrations, when

A. There is a reduction in amplitude after every cycle of vibration

B. No external force acts on a body, after giving it an initial displacement

C. A body vibrates under the influence of external force

D. None of the above

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4

Whirling speed of the shaft is the speed at which

A. Shaft tends to vibrate in longitudinal direction

B. Torsional vibrations occur

C. Shaft tends to vibrate vigorously in transverse direction

D. Combination of transverse and longitudinal vibration occurs

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4

The centrifugal tension in belts

A. Increases power transmitted

B. Decreases power transmitted

C. Have no effect on power transmitted

D. Increases power transmitted upto a certain speed and then decreases

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4

The balancing weights are introduced in planes parallel to the plane of rotation of the disturbing mass. To obtain complete dynamic balance, the minimum number of balancing weights to be introduced in different planes is

A. 1

B. 2

C. 3

D. 4

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4

The type of gears used to connect two non parallel and non intersecting shafts is

A. Spur gear

B. Helical gear

C. Bevel gear

D. Spiral gear

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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

The sensitiveness of the governor __________ as the speed range decreases.

A. Remains unaffected

B. Decreases

C. Increases

D. None of these

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4

The ratio of height of Porter governor (when length of arms and links are equal) to the height of Watt's governor is (where m = Mass of the ball, and M = Mass on the sleeve)

A. m/(m + M)

B. M/(m + M)

C. (m + M)/m

D. (m + M)/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

Governor is used in automobile to

A. Decrease the variation of speed

B. Maximize the fuel economy

C. Limit the vehicle speed

D. Maintain constant engine speed