mechanical engineering MCQs – Page 81

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

4001. Stress concentration in static loading is more serious in__________________?
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A. ductile materials

B. brittle materials

C. equally serious in both cases

D. depends on other factors

E. unpredictable

4002. If a spring is cut down into two springs, the stiffness of cut springs will be _________________?
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A. unpredictable

B. none of the above

C. half

D. double

E. same

4003. Which process will increase the fatigue duration of parts ?
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A. decarburisation

B. electroplating

C. shot-peening

D. all of the above.

E. finishing and polishing

4004. The pitch of threads on a Jock nut in comparison to pitch of nut is_________________?
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A. very fine

B. same

C. very coarse

D. coarser

E. finer

4005. If an unsupported uniform cross sectional elastic bar is subjected to a longitudinal impact from a rigid bob moving with velocity v, then a compressive wave of intensity sc is propagated through the bar as follows______________________?
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A. none of the above, where E = modulus of elasticity and p = mass density

B. vVvF

C. WpE/2

D. vpE

E. IvHpE

4006. Tensile strength of a mild steel specimen can be roughly predicted from following hardness test_________________?
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A. Vicker

B. Shores sceleroscope

C. Rockwell

D. Brinell

E. none of the above

4007. Eye bolts are used for_________________?
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A. transmission of power

B. absorbing shock and vibrations

C. foundation purposes

D. locking devices *

E. lifting and transportation of machines and cubicles
4008. Stress concentration in cyclic loading is more serious in__________________?
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A. ductile materials

B. brittle materials

C. equally serious in both cases

D. depends on other factors

E. unpredictable

4009. The draw of cotter need not exceed_________________?
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A. 25 mm

B. 10 mm

C. 20 mm

D. 5 mm

E. 3 mm
4010. The connecting rod bolts are tightened up with initial tension greater than the external load so that___________________?
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A. bolts are weakest elements

B. bolts will not loosen during service

C. joint may not open up

D. the resultant load on the bolt would not be affected by the external cyclic load

E. none of the above

4011. In cross or regular lay ropes_________________?
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A. wires are not twisted

B. wires in two adjacent strands are twisted in opposite direction

C. direction of twist of wires and strands are same

D. direction of twist of wires in strands is opposite to the direction of twist of strands

E. none of the above

4012. Cold working________________?
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A. decreases the fatigue strength

B. increases the fatigue strength

C. none of the above

D. alone has no influence on fatigue strength

E. has no influence on fatigue strength

4013. The endurance limit of a material with finished surface in comparison to rough surface is_________________?
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A. more or less depending on quantum of load

B. more

C. less

D. unpredictable

E. same

4014. At low temperatures (say 75C) the notched-bar impact value of steel____________________?
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A. depends on heat treatment carried out

B. none of the above

C. remains same

D. decreases markedly

E. increases markedly

4015. Applications in which stresses are encountered in one direction only uses following type of threads____________________?
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A. BSW

B. metric

C. square

D. buttress

E. acme

4016. Oil in journal bearing should be applied at the point where load is________________?
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A. maximum

B. unpredictable

C. average

D. nil or lightest

E. any one of the above

4017. The edges of the plates for cylindrical vessels are usually bevelled to an angle of 80 for_________________?
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A. reducing stress concentration

B. all of the above

C. safety

D. ease of manufacture

E. fullering and caulking
4018. The connecting rod bolts are tightened up so that tightening stress _________________?
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A. is about yield point divided by safety factor

B. none of the above

C. approaches yield point

D. is just sufficient to hold parts together

E. is 50% of yield point

4019. Resistance to fatigue of a material is measured by________________?
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A. Youngs modulus

B. endurance limit

C. ultimate tensile strength

D. elastic limit

E. coefficient of elasticity

4020. The valve rod in a steam engine is connected to an eccentric rod by_________________?
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A. universal coupling

B. kunckle joint

C. gib and cotter joint

D. cotter joint

E. bolted joint

4021. Fatigue strength can be increased by__________________?
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A. cold working

B. hot working

C. shot peening

D. using gradual changes of section

E. grinding and lapping surface

4022. If d is the diameter of bolt hole then for a flanged pipe joint to be leak proof, the circumferential pitch of the bolts should be_________________?
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A. 20Vdto30Vd

B. 30V5?to40Vd

C. lOVZ

D. 10VZtol5Vd

E. 15Vdto20VZ

4023. Fibrous fracture occurs in_____________?
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A. hard material

B. brittle material

C. ductile material

D. elastic material

E. all of the above

4024. Which of the following pipe joints would be suitable for pipes carrying steam_____________?
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A. threaded

B. flanged

C. compression

D. expansion

E. bell and spigot

4025. Other method of reducing shock load in the above case can be_________________?
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A. unaffected by length

B. to increase length

C. none of the above

D. to decrease length

E. other factors would decide same

4026. Plastic flow in ductile materials_____________________?
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A. depends on other considerations

B. lessens the seriousness of static loading stress concentration

C. none of the above

D. increases the seriousness of static load-ing stress concentration

E. has no effect on it

4027. Turn buckle has____________________?
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A. right hand threads on bout ends

B. left hand threads on both ends

C. left hand threads on one end and right hand threads on other end

D. no threads

E. threads in middle portion

4028. Belt slip may occur due to________________?
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A. loose belt

B. driving pulley too small

C. all of the above

D. none of the above

E. heavy load

4029. Stress concentration in cyclic loading is____________________?
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A. ch is correct statement ?

B. very serious in brittle materials and less serious in ductile materials

C. very serious in ductile materials and less serious in brittle materials

D. equally serious in both types of materials

E. seriousness would depend on other factors

F. none of the above

4030. A bolt___________________?
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A. has a head on one end and a nut fitted to the other

B. has head at one end and other end fits into a tapped hole in the other part to be joined

C. has both the ends threaded

D. is provided with pointed threads

E. requires no nut

4031. Castle nut is a locking device in which__________________?
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A. a hard fiber or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip

B. a slot is cut partly is middle of nut and then slot reduced by tightening a screw

C. one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming

D. through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin spitted and bent in reverse direction at other end

E. none of the above.

4032. Gear box is used___________________?
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A. to obtain variable speeds

B. for speed reduction

C. to damp out vibrations

D. to increase efficiency of system

E. to produce torque

4033. A key made from a cylindrical disc having segmental cross-section, is known as______________?
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A. feather key

B. hollow saddle key

C. flat saddle key

D. gib head key

E. wood-ruff key
4034. Brittle coating technique is used for_________________?
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A. protecting metal against corrosion

B. determining brittleness

C. protecting metal against wear and tear

D. non-destructive testing of metals

E. experimental stress analysis
4035. For standard coarse threads of nut, the threads will be as strong in failure by shear as the bolt in tension, if the height of nut (h) is approximately________________?
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A. 0.7 times

B. 0.8 times

C. 0.4 times

D. 0.6 times

E. 0.9 times the normal diameter of bolt

4036. Form coefficient of spring is _____________________?
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A. load required to produce unit deflection

B. its capability of storing energy

C. concerned With strength of wire of spring

D. ratio of coil diameter to wire diameter

E. nothing

4037. Ball bearing type screws are found in following application_____________________?
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A. aeroplane engines

B. bench vice

C. steering mechanism

D. crane

E. screw jack

4038. The shock absorbing capacity of a bolt can be increased by___________________?
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A. tightening it properly

B. grinding the shank

C. making shank diameter equal to core diameter of thread

D. increasing shank diameter

E. using washer

4039. The property of a material which enables it to resist fracture due to high impact loads is known as__________________?
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A. endurance

B. strength

C. elasticity

D. toughness

E. resilience

4040. Cap screws are___________________?
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A. slotted for a screw driver and generally used with a nut

B. similar to stud

C. used to prevent relative motion be-tween parts

D. similar tosmall size tap bolts except that a greater variety of shapes of heads are available

E. provided with detachable caps

4041. The building up of worn and uridersized parts, subjected to repeated loads by electroplating is_____________________?
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A. best method

B. extremely hazardous

C. cheapest method

D. has no effect as regards fatigue strength

E. all of the above

4042. When a close coiled helical spring is compressed, its wire is subjected to________________?
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A. shear

B. compression

C. all of the above

D. tension

E. none of the above

4043. Stress concentration in static loading is_________________?
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A. ch is correct statement ?

4044. Machine screws are________________?
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A. used to prevent relative motion be-tween two parts

B. none of the above

C. similar to stud

D. slotted for a screw driver and generally used with a nut

E. similar to small size tap bolts except that a greater variety of shapes of heads are available

4045. In order to avoid tearing of the plate at edge, the distance from the center line of the rivet hole to the nearest edge of the plate in terms of dia of rivet d should be equal to__________________?
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A. 1.75 d

B. 2 d.

C. 1.5 d

D. d

E. 1.25 d

4046. The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is_________________?
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A. larger

B. equal

C. smaller

D. larger/smaller depending on diameter of spring coil

E. unpredictable

4047. If d is the normal diameter of a bolt in mm, then the initial tension in kg in a bolt used for making a fluid tight joint as for steam engine cover joint is calculated by the relation_______________?
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A. 138 d

B. 168 d

C. 151 d

D. 124 d

E. 102 d

4048. When two springs are in series (having stiffness K), the equivalent stiffness will be________________?
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A. 2K

B. UK

C. K/2

D. KIA

E. K

4049. Spring stiffness is__________________?
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A. its capability of storing energy

B. ratio of coil diameter to wire diameter

C. none of the above

D. its ability to absorb shocks

E. load required to produce unit deflection
4050. If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to___________________?
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A. 1.25 x diameter of bolt

B. 1.5 x diameter of bolt

C. diameter of bolt

D. 0.5 x diameter of bolt

E. 0.75 x diameter of bolt