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Current Affairs January 2024

What is the correct answer?

4

The maximum fluctuation of energy is the

A. Difference between the maximum and minimum energies

B. Sum of the maximum and minimum energies

C. Variations of energy above and below the mean resisting torque line

D. Ratio of the mean resisting torque to the workdone per cycle

Correct Answer :

A. Difference between the maximum and minimum energies


Related Questions

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4

The type of pair formed by two elements which are so connected that one is constrained to turn or revolve about a fixed axis of another element is known as

A. Turning pair

B. Rolling pair

C. Sliding pair

D. Spherical pair

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4

A typewriter mechanism has 7 numbers of binary joints, six links and none of higher pairs. The mechanism is

A. Kinematically sound

B. Not sound

C. Soundness would depend upon which link is kept fixed

D. Data is not sufficient to determine same

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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

Frequency of vibrations is usually expressed in

A. Number of cycles per hour

B. Number of cycles per minute

C. Number of cycles per second

D. None of these

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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

3.The retardation of a flat faced follower when it has contact at the apex of the nose of a circular arc cam, is given by (where OQ = Distance between the centre of circular flank and centre of nose)

A. ω² × OQ

B. ω² × OQ sinθ

C. ω² × OQ cosθ

D. ω² × OQ tanθ

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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

A thin circular disc is rolling with a uniform linear speed, along a straight path on a plane surface. Which of the following statement is correct in this regard?

A. All points of the disc have the same velocity

B. The centre of the disc has zero acceleration

C. The centre of the disc has centrifugal acceleration

D. The point on the disc making contact with the plane surface has zero acceleration

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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

A point B on a rigid link AB moves with respect to A with angular velocity ω rad/s. The radial component of the acceleration of B with respect to A, is (where vBA = Linear velocity of B with respect to A)

A. vBA × AB

B. vBA /AB

C. BA

D. BA /AB

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4

The lower pair is a

A. Open pair

B. Closed pair

C. Sliding pair

D. Point contact pair

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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

A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is

A. 5,367 r.p.m.

B. 6,000 r.p.m.

C. 9,360 r.p.m.

D. 12,000 r.p.m.

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4

In a differential band brake as shown in the below figure, the drum rotates anticlockwise and the greater tension T₁ acts at A and smaller tension T₂ at B. Length OA is greater than length OB. In order to apply the brake, the force P at C should

A. Be zero

B. Act in upward direction

C. Act in downward direction

D. None of the above

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4

A mechanism __________ for transmitting or transforming motion.

A. Can be used

B. Cannot be used

C. Unpredictable

D. None of these

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4

The frictional torque transmitted in a flat pivot bearing, assuming uniform wear, is (Where μ = Coefficient of friction, W=Load over the bearing, R=Radius of bearing)

A. μwr

B. ¾μWR

C. (2/3) μWR

D. ½μWR

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4

The coriolis component of acceleration is taken into account for

A. Slider crank mechanism

B. Four bar chain mechanism

C. Quick return motion mechanism

D. All of these

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4

Which of the following statements regarding laws governing the friction between dry surfaces are correct?

A. The friction force is dependent on the materials of the contact surfaces.

B. The friction force is directly proportional to the normal force.

C. The friction force is independent of me area of contact.

D. All of the above

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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

For two governors A and B, the lift of sleeve of governor A is more than that of governor B, for a given fractional change in speed. It indicates that

A. Governor A is more sensitive than governor B

B. Governor B is more sensitive than governor A

C. Both governors A and B are equally sensitive

D. None of the above

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4

In a Hartnell governor, if a spring of greater stiffness is used, then the governor will be

A. Less sensitive

B. More sensitive

C. Unaffected of sensitivity

D. Isochronous

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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

A body in motion will be subjected to coriolis acceleration when that body is

A. In plane rotation with variable velocity

B. In plane translation with variable velocity

C. In plane motion which is a resultant of plane translation and rotation

D. Restrained to rotate while sliding over another body

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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

In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where μ = Coefficient of friction between the blocks and the drum, θ = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)

A. T₁/T₂ = μ. θ. n

B. T₁/T₂ = [(1 - μ tanθ)/(1 + μ tanθ)]n

C. T₁/T₂ = (μ θ)n

D. T₁/T₂ = [(1 + μ tanθ)/(1 - μ tanθ)]n

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4

A rigid body, under the action of external forces, can be replaced by two masses placed at a fixed distance apart. The two masses form an equivalent dynamical system, if

A. The sum of the two masses is equal to the total mass of body

B. The centre of gravity of the two masses coincides with that of the body

C. The sum of mass moment of inertia of the masses about their centre of gravity is equal to the mass moment of inertia of the body

D. All of the above

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4

The height of a Watt's governor is

A. Directly proportional to speed

B. Directly proportional to (speed)²

C. Inversely proportional to speed

D. Inversely proportional to (speed)²

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4

For an isochronous Hartnell governor (where r₁ and r₂ = Maximum and minimum radius of rotation of balls respectively, S₁ and S₂ = Maximum and minimum force exerted on the sleeve respectively, and M = Mass on the sleeve)

A. (m.g + S₁)/(m.g + S₂) = r₁/r₂

B. (m.g - S₁)/(m.g - S₂) = r₂/r₁

C. S₁/S₂ = r₁/r₂

D. S₂/S₁ = r₁/r₂

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4

In a turning moment diagram, the variations of energy above and below the mean resisting torque line is called

A. Fluctuation of energy

B. Maximum fluctuation of energy

C. Coefficient of fluctuation of energy

D. None of these

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4

In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be (where ω = Angular speed of the system, ωn = Natural frequency of vibration of the system)

A. Less than unity

B. Equal to unity

C. Greater than unity

D. Zero