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4

In a screw jack, the effort required to lower the load W is given by

A. P = W tan(α - φ)

B. P = W tan(α + φ)

C. P = W tan(φ - α)

D. P = W cos(α + φ)

Correct Answer :

C. P = W tan(φ - α)


Related Questions

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4

In a cone pulley, if the sum of radii of the pulleys on the driving and driven shafts is Constant, then

A. Open belt drive is recommended

B. Crossed belt drive is recommended

C. Both open belt drive and crossed belt drive is recommended

D. The drive is recommended depending upon the torque transmitted

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4

The contact ratio is the ratio of

A. Length of pair of contact to the circular pitch

B. Length of arc of contact to the circular pitch

C. Length of arc of approach to the circular pitch

D. Length of arc of recess to the circular pitch

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4

Angle of action of cam is defined as the angle

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

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

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

D. Moved by the cam from beginning of ascent to the termination of descent

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4

In a drag link quick return mechanism, the shortest link is always fixed. The sum of the shortest and longest link is

A. Equal to sum of other two

B. Greater than sum of other two

C. Less than sum of other two

D. There is no such relationship

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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

If some links are connected such that motion between them can take place in more than one direction, it is called

A. Incompletely constrained motion

B. Partially constrained motion

C. Completely constrained motion

D. Successfully constrained motion

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4

The velocity of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by (where ω = Angular velocity of the cam shaft)

A. ω (r₁ r₂) sinθ

B. ω (r₁ + r₂) sinθ sec2θ

C. ω (r₁ r₂) cosθ

D. ω (r₁ + r₂) cosθ cosec2θ

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4

In a multiple V-belt drive, when a single belt is damaged, it is preferable to change the complete set to

A. Reduce vibration

B. Reduce slip

C. Ensure uniform loading

D. Ensure proper alignment

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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

The relation between number of links (l) and number of joints (j) in a kinematic chain is

A. l = (1/2).(j + 2)

B. l = (2/3).(j + 2)

C. l = (3/4).(j + 3)

D. l = j + 4

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4

In locomotives, the ratio of the connecting rod length to me crank radius is kept very large in order to

A. Minimise the effect of primary forces

B. Minimise the effect of secondary forces

C. Have perfect balancing

D. To start the locomotive quickly

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4

In under damped vibrating system, the amplitude of vibration

A. Decreases linearly with time

B. Increases linearly with time

C. Decreases exponentially with time

D. Increases exponentially with time

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4

The tractive force in a locomotive with two cylinders is given by (where c = Fraction of reciprocating parts per cylinder, m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, and θ = Angle of inclination of crank to the line of stroke)

A. m.ω².r cosθ

B. c.m.ω².r sinθ

C. (1 - c).m.ω².r (cosθ - sinθ)

D. m.ω².r (cosθ - sinθ)

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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

Crowning on pulleys helps

A. In increasing velocity ratio

B. In decreasing the slip of the belt

C. For automatic adjustment of belt position so that belt runs centrally

D. Increase belt and pulley life

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4

Under logarithmic decrement, the amplitude of successive vibrations are

A. Constant

B. In arithmetic progression

C. In geometric progression

D. In logarithmic progression

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4

The power transmitted by a belt is maximum when the maximum tension in the belt is _________ of centrifugal tension.

A. One-third

B. Two-third

C. Double

D. Three times

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4

A circular bar moving in a round hole is an example of

A. Incompletely constrained motion

B. Partially constrained motion

C. Completely constrained motion

D. Successfully constrained motion

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4

To obviate axial thrust, following gear drive is used

A. Double helical gears having opposite teeth

B. Double helical gears having identical teeth

C. Single helical gear in which one of the teeth of helix angle a is more

D. Mutter gears

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4

There are six gears A, B, C, D, E and F in a compound train. The numbers of teeth in the gears are 20, 60, 30, 80, 25 and 75 respectively. The ratio of angular speeds of the driven (F) to the driver (A) of the drive is

A. 1/24

B. 1/8

C. 4/15

D. 12

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4

In a disc clutch, if there are n₁ number of discs on the driving shaft and n₂ number of discs on the driven shaft, then the number of pairs of contact surfaces will be

A. n₁ + n₂

B. n₁ + n₂ + 1

C. n₁ + n₂ - 1

D. n₁ + n₂ - 2

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4

Kinematic pairs are those which have two elements that

A. Have line contact

B. Have surface contact

C. Permit relative motion

D. Are held together

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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

The example of higher pair is

A. Belt, rope and chain drives

B. Gears, cams

C. Ball and roller bearings

D. All of the above

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4

Balancing of rotating and reciprocating parts of an engine is necessary when it runs at

A. Slow speed

B. Moderate speed

C. Highs peed

D. Any one of these

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4

Pulley in a belt drive acts as

A. Cylindrical pair

B. Turning pair

C. Rolling pair

D. Sliding pair

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4

Klein's construction is useful to determine

A. Velocity of various parts

B. Acceleration of various parts

C. Displacement of various parts

D. Angular acceleration of various parts

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4

Which of the following mechanisms produces mathematically an exact straight line motion?

A. Grasshopper mechanism

B. Watt mechanism

C. Peaucellier's mechanism

D. Tchebicheff mechanism

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4

What is the number of instantaneous centres for an eight link mechanism?

A. 15

B. 28

C. 30

D. 8

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4

Critical damping is a function of

A. Mass and stiffness

B. Mass and damping coefficient

C. Mass and natural frequency

D. Damping coefficient and natural frequency