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4

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

Correct Answer :

D. Higher pair


Related Questions

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4

In an ideal machine, the output as compared to input is

A. Less

B. More

C. Equal

D. May be less or more depending on efficiency

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4

In a rigid link OA, velocity of A w.r.t. O will be

A. Parallel to OA

B. Perpendicular to OA

C. At 45° to OA

D. Along AO

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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

Instantaneous center of rotation of a link in a four bar mechanism lies on

A. Right side pivot of this link

B. Left side pivot of this link

C. A point obtained by intersection on extending adjoining links

D. Cant occur

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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

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

When the crank is at the inner dead centre, in a reciprocating steam engine, then the acceleration of the piston will be

A. ω²r. (n + 1)/n

B. ω²r. (n - 1)/n

C. ω²r. n/(n + 1)

D. ω²r. n/(n - 1)

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4

In a single slider crank chain

A. Each of the four pairs is a turning pair

B. One is a turning pair and three are sliding pairs

C. Two are turning pairs and two are sliding pairs

D. Three are turning pairs and one is a sliding pair

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4

A single degree of freedom system is given by, m × (d²x/dt²) + c × (dx/dt) + sx = F.cosω.t with usual notations. It represents

A. Free vibration with damping

B. Free vibration without damping

C. Forced vibration with damping

D. Forced vibration without damping

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4

Torsional vibrations are said to occur when the particles of a body moves

A. Perpendicular to its axis

B. Parallel to its axis

C. In a circle about its axis

D. None of these

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4

Which of the following disciplines provides study of relative motion between the parts of a machine?

A. Theory of machines

B. Applied mechanics

C. Mechanisms

D. Kinematics

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4

According to Kennedy's theorem, if three bodies have plane motions, their instantaneous centers lie on

A. A triangle

B. A point

C. Two lines

D. A straight line

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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

If ω/ωn = 2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will the

A. 0.5

B. 1

C. 1.5

D. 2

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4

Kinematic pairs are those which have

A. Point or line contact between the two elements when in motion

B. Surface contact between the two elements when in motion

C. Elements of pairs not held together mechanically

D. Two elements that permit relative motion

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4

ABCD is a four bar mechanism in which AB = 310 mm and CD = 450 mm. AB and CD are both perpendicular to the fixed link AD, as shown in the below figure. If the velocity of B at this condition is v. Then the velocity of C is

A. v

B. (2/3). v

C. (3/2). v

D. (9/4). v

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4

Cam angle is defined as the angle

A. During which the follower returns to its initial position

B. Of rotation of the cam for a definite displacement of the follower

C. Through which, the cam rotates during the period in which the follower remains in the highest position

D. Moved by the cam from the instant the follower begins to rise, till it reaches its highest position

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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 radius of a friction circle for a shaft rotating inside a bearing is (where r = Radius of shaft, and tan φ = Coefficient of friction between the shaft and bearing)

A. r sinφ

B. r cosφ

C. r tanφ

D. (r/2) cosφ

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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

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4

When two links are connected by a pin joint, their instantaneous centre lies

A. On their point of contact

B. At the centre of curvature

C. At the centre of circle

D. At the pin joint

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4

In a four-bar chain it is required to give an oscillatory motion to the follower for a continuous rotation of the crank. For the lengths of 50 mm of crank and 70 mm of the follower, determine theoretical maximum length of coupler. The minimum length of the coupler will be

A. 45 mm

B. Slightly less than 45 mm

C. Slightly more than 45 mm

D. 95 mm

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4

In a screw jack, the effort required to lift the load W is given by (where α = Helix angle, and φ = Angle of friction)

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

Creep in belt drive is due to

A. Material of the pulley

B. Material of the belt

C. Larger size of the driver pulley

D. Uneven extensions and contractions due to varying tension

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4

In a Hartnell governor, the lift of the sleeve is given by (where r₁ and r₂ = Max. and min. radii of rotation, x = Length of ball arm of the lever, and y = Length of sleeve arm of the lever)

A. (r₁ + r₂) (y/x)

B. (r₁ + r₂) (x/y)

C. (r₁ - r₂) (y/x)

D. (r₁ - r₂) (x/y)

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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

An exact straight line motion mechanism is a

A. Scott-Russell's mechanism

B. Hart's mechanism

C. Peaucellier's mechanism

D. All of these

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4

A shaft carrying two rotors at its ends will have

A. No node

B. One node

C. Two nodes

D. Three nodes

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4

The displacement of a flat faced follower when it has contact with the flank of a circular arc cam, is given by (where R = Radius of flank, r₁ = Minimum radius of the cam, and θ = Angle turned through by the cam)

A. R (1 - cosθ)

B. (R - r₁) (1 - cosθ)

C. R (1 - sinθ)

D. (R - r₁) (1 - sinθ)

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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.