Efficiency of the screw _______ with increase of coefficient of friction. a) decreases b) increases c) has no effect d) cannot be determined

Efficiency of the screw _______ with increase of coefficient of friction.

a) decreases

b) increases

c) has no effect

d) cannot be determined
by

1 Answer

Answer :

a) decreases
by

Related questions

In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing. [IES-1995] (a) Remains constant at all speeds. (b) is minimum at zero speed and increases monotonically with increase in speed. (c) is maximum at zero speed and decreases monotonically with increase in speed. (d) becomes minimum at an optimum speed and then increases with further increase in speed.

Description : In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing. [IES-1995] (a) Remains constant at all speeds. (b) is minimum at zero speed and increases ... speed. (d) becomes minimum at an optimum speed and then increases with further increase in speed.

Last Answer : (d) becomes minimum at an optimum speed and then increases with further increase in speed.

Efficiency of the screw depends upon helix angle but does not depend on friction angle. a) True b) False

Description : Efficiency of the screw depends upon helix angle but does not depend on friction angle. a) True b) False

Last Answer : b) False

Use of multiple notches in a V shaped flat plate will a) Reduce the stress concentration b) Increase the stress concentration c) No effect d) Cannot be determined

Description : Use of multiple notches in a V shaped flat plate will a) Reduce the stress concentration b) Increase the stress concentration c) No effect d) Cannot be determined

Last Answer : a) Reduce the stress concentration

Increase in values of which of the following results in an increase of the coefficient of friction in a hydrodynamic bearing? [IES 2007] 1. Viscosity of the oil. 2. Clearance between shaft and bearing. 3. Shaft speed. Select the using the code given below: (a) 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Description : Increase in values of which of the following results in an increase of the coefficient of friction in a hydrodynamic bearing? [IES 2007] 1. Viscosity of the oil. 2. Clearance between shaft and bearing. 3. Shaft speed. Select the ... 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Last Answer : (b) 1 and 3 only

Jam nut is a locking device in which (A) A smaller nut is tightened against main nut creating friction at the contacting surface (B) A split pin is passed through diametrically opposite slots in nut and a hole in bolt and the two ends of split pin are separated and bent back on nut (C) A slot is cut in the middle of nut along the length and a cap screw is provided to tighten the two parts of nut separated by slot (D) An elastic piece is tightened in the nut by a setscrew

Description : Jam nut is a locking device in which (A) A smaller nut is tightened against main nut creating friction at the contacting surface (B) A split pin is passed through diametrically opposite slots in nut and ... parts of nut separated by slot (D) An elastic piece is tightened in the nut by a setscrew

Last Answer : (A) A smaller nut is tightened against main nut creating friction at the contacting surface

Castle nut is a locking device in which (A) A smaller nut is tightened against main nut creating friction at the contacting surface (B) A split pin is passed through diametrically opposite slots in nut and a hole in bolt and the two ends of split pin are separated and bent back on nut (C) A slot is cut in the middle of nut along the length and a cap screw is provided to tighten the two parts of nut separated by slot (D) An elastic piece is tightened in the nut by a setscrew

Description : Castle nut is a locking device in which (A) A smaller nut is tightened against main nut creating friction at the contacting surface (B) A split pin is passed through diametrically opposite slots in nut and ... of nut separated by slot (D) An elastic piece is tightened in the nut by a setscrew

Last Answer : (B) A split pin is passed through diametrically opposite slots in nut and a hole in bolt and the two ends of split pin are separated and bent back on nut

Maximum possible efficiency of a self-locking screw is a) 50% b) 75% c) 66% d) 33%

Description : Maximum possible efficiency of a self-locking screw is a) 50% b) 75% c) 66% d) 33%

Last Answer : a) 50%

Efficiency of screw depends upon lead of the screw. a) True b) False

Description : Efficiency of screw depends upon lead of the screw. a) True b) False

Last Answer : a) True

Threads used in screw fasteners are ______ a. having high strength b. having low efficiency c. single start type d. all of the above

Description : Threads used in screw fasteners are ______ a. having high strength b. having low efficiency c. single start type d. all of the above

Last Answer : d. all of the above

The maximum efficiency of a square threaded screw is (A) (1 - sinφ)/ (1 + sinφ) (B) (1 + sinφ)/ (1 - sinφ)s (C) (1 - sinφ)/ (1 + cosφ) (D) (1 + cosφ)/ (1 - sinφ)

Description : The maximum efficiency of a square threaded screw is (A) (1 - sinφ)/ (1 + sinφ) (B) (1 + sinφ)/ (1 - sinφ)s (C) (1 - sinφ)/ (1 + cosφ) (D) (1 + cosφ)/ (1 - sinφ)

Last Answer : (A) (1 - sinφ)/ (1 + sinφ)

Partial bearing is preferred over journal bearing. a) True b) No c) More friction losses d) Can’t be determined

Description : Partial bearing is preferred over journal bearing. a) True b) No c) More friction losses d) Can’t be determined

Last Answer : a) True

In a journal bearings, the radius of the friction circle increases with the increase in- [IES-1997] (a) Load (b) Radius of the journal (c) Speed of the journal (d) Viscosity of the lubricant

Description : In a journal bearings, the radius of the friction circle increases with the increase in- [IES-1997] (a) Load (b) Radius of the journal (c) Speed of the journal (d) Viscosity of the lubricant

Last Answer : (b) Radius of the journal

Assertion (A): Oil as a cutting fluid result in a lower coefficient of friction. Reason (R): Oil forms a thin liquid film between the tool face and chip, and it provides 'hydrodynamic lubrication'. [IES- 2000] (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true

Description : Assertion (A): Oil as a cutting fluid result in a lower coefficient of friction. Reason (R): Oil forms a thin liquid film between the tool face and chip, and it provides 'hydrodynamic lubrication'. [IES- 2000] (a ... explanation of A (c) A is true but R is false (d) A is false but R is true

Last Answer : (c) A is true but R is false

Satisfactory hydrodynamic film in a journal bearing is formed when (a) Journal speed is low; unit pressure on the bearing is high and viscosity of lubricant used is low [IES-2006] (b) Journal speed is low; unit pressure on the bearing is low and viscosity of lubricant used is low (c) Journal speed is high; unit pressure on the bearing is high and viscosity of lubricant used is high (d) Appropriate combination of journal speed, unit pressure on bearing and lubricant viscosity exists resulting in low coefficient of friction

Description : Satisfactory hydrodynamic film in a journal bearing is formed when (a) Journal speed is low; unit pressure on the bearing is high and viscosity of lubricant used is low [IES-2006] ... journal speed, unit pressure on bearing and lubricant viscosity exists resulting in low coefficient of friction

Last Answer : (c) Journal speed is high; unit pressure on the bearing is high and viscosity of lubricant used is high

Consider tile following statements: [IES-1993; 2002; 2006] Radius of friction circle for a journal bearing depends upon 1. Coefficient of friction 2. Radius of the journal 3. Angular speed of rotation of the shaft Which of the statements given above are correct? (a) 1,2 and 3 (b) Only 1 and 2 (c) Only 2 and 3 (d) Only 1 and 3

Description : Consider tile following statements: [IES-1993; 2002; 2006] Radius of friction circle for a journal bearing depends upon 1. Coefficient of friction 2. Radius of the journal 3. Angular speed of rotation of the shaft Which of the ... ) 1,2 and 3 (b) Only 1 and 2 (c) Only 2 and 3 (d) Only 1 and 3

Last Answer : (b) Only 1 and 2

Which of the following are not true for petroff’s equation? a) Shaft is considered concentric with the bearing b) Bearing is subjected to light load c) Is used to find coefficient of friction d) Frictional torque is given by fpr2l

Description : Which of the following are not true for petroff’s equation? a) Shaft is considered concentric with the bearing b) Bearing is subjected to light load c) Is used to find coefficient of friction d) Frictional torque is given by fpr2l

Last Answer : d) Frictional torque is given by fpr2l

In trapezoidal threads, f (coefficient of friction) can be taken as a) f sec θ b) f cos θ c) f sin θ d) f cosec θ

Description : In trapezoidal threads, f (coefficient of friction) can be taken as a) f sec θ b) f cos θ c) f sin θ d) f cosec θ

Last Answer : a) f sec θ

Self-locking takes place when a) Coefficient of friction is equal to or greater than the tangent of the helix angle b) Coefficient of friction is lesser than or equal to the tangent of the helix angle c) Coefficient of friction is equal to or greater than the tangent of the helix angle d) None of the mentioned

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Last Answer : c) Coefficient of friction is equal to or greater than the tangent of the helix angle

If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the diameter of each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. Permissible tensile stress is 80N/mm2. a) 27mm b) 25mm c) 23mm d) 21mm

Description : If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the diameter of each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. Permissible tensile stress is 80N/mm2. a) 27mm b) 25mm c) 23mm d) 21mm

Last Answer : a) 27mm

If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the tensile force on each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. a) 51234.4N b) 45968.3N c) 41666.7N d) None of the listed

Description : If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the tensile force on each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. a) 51234.4N b) 45968.3N c) 41666.7N d) None of the listed

Last Answer : c) 41666.7N

When comes down to stress reduction, which one is preferred? a) Solid flywheel b) Split flywheel c) Both have equal stresses d) Cannot be determined

Description : When comes down to stress reduction, which one is preferred? a) Solid flywheel b) Split flywheel c) Both have equal stresses d) Cannot be determined

Last Answer : b) Split flywheel

If we exclude the cost factor, which bearing is preferred? a) Hydrostatic b) Hydrodynamic c) Both are equally preferred d) Cannot be determined

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If spring index=2.5, what can be concluded about stresses in the wire? a) They are high b) They are negligible c) They are moderate d) Cannot be determined

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Last Answer : a) They are high

Among gas and electric arc welding, which has the higher rate of heating? a) Gas welding b) Electric arc welding c) Gas welding and electric arc welding have equal rate of heating d) Cannot be determined

Description : Among gas and electric arc welding, which has the higher rate of heating? a) Gas welding b) Electric arc welding c) Gas welding and electric arc welding have equal rate of heating d) Cannot be determined

Last Answer : b) Electric arc welding

Which threads have greater resistance to unscrewing? a) Coarse b) Fine c) They have equal resistance d) Cannot be determined

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For an elliptical hole on a flat plate, if width of the hole in direction of the load decrease, Stress Concentration Factor will______ a) Increase b) Decrease c) Remains constant d) Can’t be determined. Varies from material to material

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If the centre distance of the mating gears having involute teeth is varied within limits, the velocity ratio (A) Increases (B) Decreases (C) Remains unchanged (D) None of these

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If the lateral force acting on the set screw is large and tends to displace one part with respect to other than which point is recommended? a) Dog Point b) Cone Point c) Window Point d) Cut Point

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If a fastener is threaded into a tapped hole, then the fastener is likely to be called as a) Screw b) Bolt c) Washer d) Screw or bolt

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Nominal diameter of the screw thread is the same as core diameter. a) True b) False

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Which type of screw fasteners are threaded through out its length? a. Cap screws b. Set screws c. Studs d. Tap bolt

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Allen key is used to tighten (A) Cap screw with hexagonal head (B) Cap screw with fillister head (C) Cap screw with hexagonal socket head (D) Cap screw with flat head

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A screw is specified by (A) Major diameter (B) Minor diameter (C) Pitch diameter (D) Mean diameter

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The largest diameter of external or internal screw thread is called (A) Major diameter (B) Minor diameter (C) Pitch diameter (D) None of the above

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Last Answer : (C) Used to prevent relative motion between parts

While designing screw threads, adequate length of engaged threads between the screw and nut is provided so as to prevent failure of threads due to (A) Direct shear stress (B) Torsional shear stress (C) Tensile stress (D) Compressive stress

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Last Answer : (A) Direct shear stress

In manual assembly, cost of screw is higher than the cost of driving a screw. a) True b) False

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Coefficient of consolidation for clays normally (A) Decreases with increase in liquid limit (B) Increases with increase in liquid limit (C) First increases and then decreases with increase in liquid limit (D) Remains constant at all liquid limits

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Pick out the correct statement. (A) The slope of the stripping line is always less than unity (B) For a given separation in a binary distillation column, with increase in reflux ratio (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases (C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower

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Last Answer : C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux

Ice skating is possible and practical because of a unique property of water. Is it because: w) The coefficient of kinetic friction of steel on frozen water decreases with decreasing temperature x) Ice readily sublimes y) The melting point decreases with increasing pressure z) Ice is a good thermal insulator

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Set screws are subjected to tensile forces only. a) Yes b) No, they are subjected to compressive forces only c) Both compressive and tensile d) Can’t be determined

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Last Answer : b) No, they are subjected to compressive forces only

Volumetric efficiency of a compressor without clearance volume A. Increases with increase in compression ratio B. Decreases wit increase in compression ratio C. Not dependent upon compression ratio D. Unpredictable

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Which one of the following statement is not correct for the volumetric efficiency of a reciprocating air compressor? A. It decreases with increase in ambient temperature B. It increases with decrease in pressure ratio C. It increases with decrease in clearance ratio D. It decreases with increases in delivery pressure

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Last Answer : ANSWER : A

How the efficiency of the SI engine is affected by the specific heat ratio (γ) of the working fluid? a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working fluid b. the efficiency of the engine decreases with increase in specific heat ratio (γ) of the working fluid c. the efficiency of the engine does not affected by change in specific heat ratio (γ) of the working fluid d. none of the above

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With increase in compression ratio, the efficiency of the otto engine (A) Increases (B) Decreases (C) Remain constant (D) Increases linearly

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