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Current Affairs January 2024

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The ratio of the driving tensions for V-belts is __________ times that of flat belts. (Where β = Semi-angle of the groove)

A. sinβ

B. cosβ

C. cosecβ

D. secβ

Correct Answer :

C. cosecβ


Related Questions

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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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Which of the following property of the instantaneous centre is correct?

A. A rigid link rotates instantaneously relative to another link at the instantaneous centre for the configuration of the mechanism considered.

B. The two rigid links have no linear velocity relative to each other at the instantaneous centre.

C. The velocity of the instantaneous centre relative to any third rigid link is same whether the instantaneous centre is regarded as a point on the first rigid link or on the second rigid link.

D. All of the above

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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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The cam follower generally used in automobile engines is

A. Knife edge follower

B. Flat faced follower

C. Spherical faced follower

D. Roller follower

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When the body is suspended at the point of suspension, its periodic time and frequency will be ________ as compared to the body suspended at the point of percussion.

A. Same

B. Two times

C. Four times

D. None of these

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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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Scotch yoke mechanism is used to generate

A. Sine functions

B. Square roots

C. Logarithms

D. Inversions

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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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If two moving elements have surface contact in motion, such pair is known as

A. Sliding pair

B. Rolling pair

C. Surface pair

D. Higher pair

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In a system subjected to damped forced vibrations, the ratio of maximum displacement to the static deflection is known as

A. Critical damping ratio

B. Damping factor

C. Logarithmic decrement

D. Magnification factor

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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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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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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

Which of the following statement is correct?

A. The power absorbed in operating the piston valve is less than D-slide valve

B. The wear of the piston valve is less than the wear of the D-slide valve

C. The D-slide valve is also called outside admission valve.

D. All of the above

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4

If the radius of gyration of a compound pendulum about an axis through e.g. is more, then its frequency of oscillation will be

A. Less

B. More

C. Same

D. Data are insufficient to determine same

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The centre of percussion is below the centre of gravity of the body and is at a distance equal to

A. h/kG

B. h²/kG

C. kG²/h

D. h × kG

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4

The frictional torque transmitted in a flat pivot bearing, considering uniform pressure, is (where μ = Coefficient of friction, W = Load over the bearing, and R = Radius of bearing surface)

A. (1/2) μ W R

B. (2/3) μ W R

C. (3/4) μ W R

D. μ W R

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4

The natural frequency of free transverse vibrations due to a point load acting over a simply supported shaft is equal to (where δ = Static deflection of a simply supported shaft due to the point load)

A. 0.4985/√δ

B. 0.5615/√δ

C. 0.571/√δ

D. 0.6253/√δ

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4

For the same lift and same angle of ascent, a smaller base circle will give

A. A small value of pressure angle

B. A large value of pressure angle

C. There is no such relation with pressure angle

D. Something else

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4

Idler pulley is used

A. For changing the direction of motion of the belt

B. For applying tension

C. For increasing velocity ratio

D. All of the above

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Kinematic pairs are those which have

A. Two elements held together mechanically

B. Two elements having relative motion

C. Two elements having Coriolis component

D. Minimum of two instantaneous centres

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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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The natural frequency of free torsional vibrations of a shaft is equal to (where q = Torsional stiffness of the shaft, and I = Mass moment of inertia of the disc attached at the end of a shaft)

A. 2π. √(q/I)

B. 2π qI

C. (1/2π). √(q/I)

D. 1/2π

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Which of the following has sliding motion?

A. Crank

B. Connecting rod

C. Crank pin

D. Crosshead

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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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When a ship travels in a sea, which of the effect is more dangerous

A. Steering

B. Pitching

C. Rolling

D. All of the above

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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

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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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The example of rolling pair is

A. Bolt and nut

B. Lead screw of a lathe

C. Ball and socket joint

D. Ball bearing and roller bearing

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Which of the following is a spring controlled governor?

A. Hartnell governor

B. Hartung governor

C. Wilson-Hartnell governor

D. All of these