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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

Correct Answer :

D. ½μWR


Related Questions

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4

In an open pair, the two elements of a pair

A. Have a surface contact when in motion

B. Have a line or point contact when in motion

C. Are kept in contact by the action of external forces, when in motion

D. Are not held together mechanically

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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

Which of the following is an example of a higher pair?

A. Toothed gearing

B. Belt and rope drive

C. Ball and roller bearing

D. All of these

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4

The example of completely constrained motion is a

A. Motion of a piston in the cylinder of a steam engine

B. Motion of a square bar in a square hole

C. Motion of a shaft with collars at each end in a circular hole

D. All of the above

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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

In a ball bearing, ball and bearing forms a

A. Turning pair

B. Rolling pair

C. Screw pair

D. Spherical pair

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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

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

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

The frictional torque transmitted in a truncated conical pivot bearing, considering uniform pressure, is

A. (1/2). μ W cosecα (r₁ + r₂)

B. (2/3). μ W cosecα (r₁ + r₂)

C. (1/2). μ W cosecα [(r₁³ - r₂³)/(r₁² - r₂²)]

D. (2/3). μ W cosecα [(r₁³ - r₂³)/(r₁² - r₂²)]

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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

Maximum fluctuation of energy in a flywheel is equal to [where I = Mass moment of inertia of the flywheel, E = Maximum fluctuation of energy, CS = Coefficient of fluctuation of speed, and ω = Mean angular speed = (ω₁ + ω₂)/2]

A. I.ω.(ω₁ - ω₂)

B. I.ω².CS

C. 2.E.CS

D. All of these

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4

The factor which affects the critical speed of a shaft is

A. Diameter of disc

B. Span of shaft

C. Eccentricity

D. All of these

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4

In a kinematic chain, a quaternary joint is equivalent to

A. One binary joint

B. Two binary joints

C. Three binary joints

D. Four binary joints

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4

In a reciprocating engine, usually __________ of the reciprocating masses are balanced.

A. One-half

B. Two-third

C. Three-fourth

D. Whole

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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 size of a gear is usually specified by

A. Pressure angle

B. Circular pitch

C. Diametral pitch

D. Pitch circle diameter

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4

Which of the following statement is correct?

A. The primary unbalanced force is less than the secondary unbalanced force.

B. The primary unbalanced force is maximum twice in one revolution of the crank.

C. The unbalanced force due to reciprocating masses varies in magnitude and direction both.

D. The magnitude of swaying couple in locomotives is inversely proportional to the distance between the two cylinder centre lines

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4

Which type of gearing is used in steering system of an automobile?

A. Rack and pinion

B. Worm and wheel

C. Spiral gears

D. None of the above

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4

In the two rotor system as shown in the below figure (I₁ < I₂), a node of vibration is situated

A. Between I₁, and I₂ but nearer I₁

B. Between I₁, and I₂ but nearer to I₂

C. Exactly in the middle of the shaft

D. Nearer to I₁ but outside

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4

The component of the acceleration, parallel to the velocity of the particle, at the given instant is called

A. Radial component

B. Tangential component

C. Coriolis component

D. None of these

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4

The frictional torque transmitted by a disc or plate clutch is same as that of

A. Flat pivot bearing

B. Flat collar bearing

C. Conical pivot bearing

D. Truncated conical pivot bearing

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4

The frequency of oscillation of a torsional pendulum is

A. 2πk/r. √(g/l)

B. r/2πk. √(l/g)

C. 2πr/k. √(g/l)

D. r/2πk. √(g/l)

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4

The relation between number of pairs (p) forming a kinematic chain and the number of links (l) is

A. l = 2p - 2

B. l = 2p - 3

C. l = 2p - 4

D. l = 2p - 5

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4

The following is the inversion of slider crank chain mechanism

A. Whitworth quick return mechanism

B. Hand pump

C. Oscillating cylinder engine

D. All of the above

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4

In a differential band brake as shown in the below figure, if the length OB is greater than OA, then the force P at C should act in the downward direction.

A. Yes

B. No

C. Unpredictable

D. None of these

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4

The acceleration of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by

A. ω². (r₁ r₂). (1 - cos² θ)

B. ω². (r₁ + r₂). (1 + cos² θ)

C. ω². (r₁ + r₂). [(2 - cos² θ)/cos³ θ]

D. ω². (r₁ - r₂). (1 - sin² θ)

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4

When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be

A. To move the ship towards starboard

B. To move the ship towards port side

C. To raise the bow and lower the stern

D. To raise the stern and lower the bow

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4

The centre of gravity of a coupler link in a four bar mechanism will experience

A. No acceleration

B. Only linear acceleration

C. Only angular acceleration

D. Both linear and angular acceleration

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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