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What is the correct answer?

4

When the belt is transmitting maximum power, the belt speed should be

A. √(Pmax / 2m)

B. √(Pmax / 3m)

C. √(Pmax / m)

D. √(3m /Pmax) Where m = mass of belt per metre (kg/m) Pmax = maximum permissible tension in belt (N)

Correct Answer :

B. √(Pmax / 3m)


Related Questions

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4

According to Rankine's theory, the failure occurs at a point in a member

A. When the maximum shear stress in a biaxial stress system reaches the shear stress at elastic limit in a simple tension test

B. When the maximum principal stress in a biaxial stress system reaches the elastic limit of the material in a simple tension test

C. When the strain energy per unit volume in a biaxial stress system reaches the strain energy at the elastic limit per unit volume as determined from a simple tension test

D. When the maximum principal strain in a biaxial stress system reaches the strain at the elastic limit as determined from a simple tension test

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4

The resultant axial load on a bolt depends upon

A. External load applied

B. Initial tension due to tightening of the bolt

C. Relative elastic yielding of the bolt and the connected members

D. All of the above

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4

Which of the following formula is used in designing a connecting rod?

A. Euler's formula

B. Rankine's formula

C. Johnson's straight line formula

D. Johnson's parabolic formula

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4

For unequal width of butt straps, the thicknesses of butt straps are

A. 0.75 t for narrow strap on the inside and 0.625 t for wide strap on the outside

B. 0.75 t for wide strap on the inside and 0.625 t for narrow strap on the outside

C. 0.75 t for both the straps on the inside and outside

D. 0.625 t for both the straps on the inside and outside

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4

In nitrated parts, the origins of the fatigue cracks will occur at

A. Surface

B. Just below the surface

C. Within the core

D. None of the above

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4

The velocity factor for precision metallic gears cut with high accuracy and operating at velocities upto 20 m/s is equal to

A. 0.75/ (0.75 + √v)

B. 3/ (3 + v)

C. 4.5/ (4.5 + v)

D. 6/ (6 + v)

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4

Crowning on pulley helps

A. In decreasing the slip of the belt

B. In increasing the slip of the belt

C. To keep the belt in centre on a pulley while it is in motion

D. To increase pulley life

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4

Factor of safety for fatigue loading is the ratio of

A. Elastic limit to the working stress

B. Elastic limit to the yield point

C. Endurance limit to the working stress

D. Young's modulus to the ultimate tensile strength

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4

According to Indian standards, total numbers of tolerance grades are

A. 8

B. 12

C. 18

D. 20

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4

A crankshaft is a __________ shaft.

A. Transmission

B. Machine

C. Machine frame

D. None of these

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4

The pitch of threads on a Jock nut in comparison to pitch of nut is

A. Same

B. Coarser

C. Finer

D. Very fine

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4

Which of the following is a permanent fastening?

A. Bolts

B. Keys

C. Cotters

D. Rivets

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4

At low temperatures (say 75°C) the notched bar impact value of steel

A. Increases markedly

B. Decreases markedly

C. Remain same

D. Depends on heat treatment carried out

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4

In most machine members, the damping capacity of the material should be

A. Low

B. Zero

C. High

D. Could be anything

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4

The maximum normal stress theory is used for

A. Plastic materials

B. Brittle materials

C. Non-ferrous materials

D. Ductile materials

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4

The distribution of the forces along the length of key fitted in a shaft

A. Varies linearly

B. Is uniform throughout

C. Varies exponentially, being more near the torque-input end

D. Varies exponentially, being less near the torque-input end

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4

When two non-parallel or intersecting but coplanar shafts are connected by gears, the arrangement is known as,

A. Bevel gearing

B. Helical gearing

C. Worm gearing

D. None of these

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4

In hydrodynamic bearings

A. The oil film pressure is generated only by the rotation of the journal

B. The oil film is maintained by supplying oil under pressure

C. Do not require external supply of lubricant

D. Grease is used for lubrication

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4

When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be

A. Knuckle threads

B. Square threads

C. Acme threads

D. Buttress threads

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4

The static tooth load should be __________ the dynamic load.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The shear stress in a beam varies from zero at the outer fibres to a maximum at the________.

A. Neutral surface

B. Upper surface

C. Lower surface

D. None of these

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4

The steel pulleys are __________ in weight than cast iron pulleys of the same capacity.

A. Heavier

B. Lighter

C. Moderate

D. None of these

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4

When the belt speed increases

A. Power transmitted increases

B. Power transmitted decreases

C. Power transmitted increases to a maximum value and then decreases

D. Power transmitted remains the same

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4

According to maximum shear stress theory, the maximum shear stress in the shaft is

A. (1/2) × √(σ² + 4τ²)

B. √(σ² + 4τ²)

C. (1/2) × [σ + √(σ² + 4τ²)]

D. σ + √(σ² + 4τ²)

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4

A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is

A. 2000 N-m

B. 2050 N-m

C. 2100 N-m

D. 2136 N-m

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4

An elastic bar is fixed at the upper end and loaded at the lower end by a falling weight. The shock load produced can be reduced by

A. Increasing the length of bar

B. Decreasing the cross-sectional area of the bar

C. Decreasing the modulus of elasticity of the bar

D. All of the above

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4

The radial distance of a tooth from the pitch circle to the top of the tooth is called

A. Addendum

B. Dedendum

C. Clearance

D. Working depth

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4

The ball bearings are provided with a cage

A. To reduce friction

B. To facilitate slipping of balls

C. To prevent the lubricant from flowing out

D. To maintain the balls at a fixed distance apart

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4

The acme threads are usually found on

A. Spindles of bench vices

B. Railway carriage couplings

C. Feed mechanism of machine tools

D. Screw cutting lathes

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4

The ratio of the ultimate stress to the design stress is known as

A. Elastic limit

B. Strain

C. Factor of safety

D. Bulk modulus