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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

Correct Answer :

A. Closed pair


Related Questions

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4

The critical speed of a shaft in revolution per second is __________ as that of natural frequency of transverse vibration.

A. Same

B. Different

C. Unpredictable

D. None of these

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4

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

A. Minimum

B. Zero

C. Maximum

D. None of these

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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

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

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

The equation of free vibrations of a system is (d²x/dt²) +36 π²x, its natural frequency is

A. 3 Hz

B. 3π Hz

C. 6 Hz

D. 6π Hz

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4

The tractive force is maximum or minimum when the angle of inclination of crank with the line of stroke (θ) is equal to

A. 0° and 90°

B. 90° and 180°

C. 135° and 315°

D. 270° and 360°

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4

A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will

A. Remain same as before

B. Become equal to 2R

C. Become equal to R/2

D. Become equal to R/4

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4

A spring controlled governor is said to be isochronous when the controlling force

A. Increases as the radius of rotation decreases

B. Increases as the radius of rotation increases

C. Decreases as the radius of rotation increases

D. Remain constant for all radii of rotation

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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

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4

The displacement of the reciprocating roller follower, when it has contact with the straight flanks of the tangent cam, is given by (where r₁ = Minimum radius of the cam, r₂ = Radius of the roller follower, and θ = Angle turned by the cam from the beginning of the follower displacement)

A. (r₁ - r₂) (1 - cosθ)

B. (r₁ + r₂) (1 + cosθ)

C. (r₁ - r₂) [(1 - cosθ)/cos θ]

D. (r₁ + r₂) [(1 - cosθ)/cos θ]

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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

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

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

The axis of precession is __________ to the plane in which the axis of spin is going to rotate.

A. Parallel

B. Perpendicular

C. Both A and B

D. None of these

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4

The condition for correct steering of a Davis steering gear is (where α = Angle of inclination of the links to the vertical)

A. sinα = b/c

B. cosα = c/b

C. tanα = c/2b

D. cotα = c/2b

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4

In a flat collar pivot bearing, the moment due to friction is proportional to

A. (r₁² - r₂²)/(r₁ - r₂)

B. (r₁² - r₂²)/(r₁ + r₂)

C. (r₁³ - r₂³)/(r₁² - r₂²)

D. (r₁³ - r₂³)/(r₁ - r₂)

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4

In a steam engine, the earlier cut-off with a simple slide valve may be obtained by increasing the steam lap and the angle of advance of the eccentric but keeping constant the travel and lead of the valve, this method will

A. Cause withdrawing or throttling of steam

B. Reduce length of effective stroke of piston

C. Reduce maximum opening of port to steam

D. All of these

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4

Pitch point of a cam is

A. A point on the pitch curve having minimum pressure angle

B. A point on the pitch curve having maximum pressure angle

C. Any point on the pitch curve

D. Any point on the pitch circle

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4

Creep in belt drive is due to

A. Weak material of the belt

B. Weak material of the pulley

C. Uneven extensions and contractions of the belt when it passes from tight side to slack side

D. Expansion of the belt

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4

The critical speed of a shaft depends upon its

A. Mass

B. Stiffness

C. Mass and stiffness

D. Stiffness and eccentricity

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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

Which gear is used for connecting two coplanar and intersecting shafts?

A. Spur gear

B. Helical gear

C. Bevel gear

D. None of the above

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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

When one of the links of a kinematic chain is fixed, the chain is known as a

A. Structure

B. Mechanism

C. Inversion

D. Machine

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4

The approximate straight line mechanism is a

A. Four bar linkage

B. 6 bar linkage

C. 8 bar linkage

D. 3 bar linkage

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4

Peaucelliers mechanism has

A. Eight links

B. Six links

C. Four links

D. Twelve links

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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

When two pulleys of different diameters are connected by means of an open belt, the angle of contact at the ________ pulley must be taken into consideration.

A. Smaller

B. Larger

C. Either A or B

D. None of these

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4

Any point on a link connecting double slider crank chain will trace a

A. Straight line

B. Circle

C. Ellipse

D. Parabola