Machine Design MCQ Objective Question and Answers Part 1

Machine Design Multiple choice Objective Question useful for technical Aptitude test.

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1.钢的强度极限公司的紧张局势mparison to shear is in the ratio of
(a) 1 : l
(b) 2:1
(c) 3 : 2
(d) 2 : 3
(e) 1 : 2
Ans: c

2. The permissible stress for carbon steel under static loading is generally taken as
(a) 2000-3000 kg/cm2
(b) 3000-4000 kg/cm2
(c) 4000-4500 kg/cm2
(d) 7500-10,000 kg/cm2
(e) 10,000-15,000 kg/cm2.
Ans: c

3. The property of a material which enables it to resist fracture due to high impact loads is known as
(a) elasticity
(b) endurance
(c) strength
(d) toughness
(e) resilience.
Ans: d

4. A hot short metal is
(a) brittle when cold
(b) brittle when hot
(c) brittle under all conditions
(d) ductile at high temperature
(e) hard when hot.
Ans: b

5. Guest’s theory of failure is applicable for following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: b

6. Rankine’s theory of failure is applicable for following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: a

7. 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
(a) vpE
(b) vVvF
(c) WpE/2
(d) IvHpE
(e) none of the above, where E = modulus of elasticity and p = mass density.
Ans: a

8. Tensile strength of a mild steel specimen can be roughly predicted from following hardness test
(a) Brinell
(b) Rockwell
(c) Vicker
(d) Shore’s sceleroscope
(e) none of the above.
Ans: a

9. Resilience of a material is important, when it is subjected to
(a) combined loading
(b) fatigue
(c) thermal stresses
(d) wear and tear
(e) shock loading.
Ans: e

10. In the case of an elastic bar fixed at upper end and loaded by a falling weight at lower end, the shock load produced can be decreased by
(a) decreasing the cross-section area of’ bar
(b) increasing the cross-section area of bar
(c) remain unaffected with cross-section area
(d) would depend upon other factors
(e) none of the above.
Ans: a

11. .Other method of reducing shock load in the above case can be
(a) to decrease length
(b) to increase length
(c) unaffected by length
(d) other factors would decide same
(e) none of the above.
Ans: b

12. If a load W is applied instantaneously on a bar; then the stress induced in bar will
(a) be independent of ratio of mass of load W to mass of bar (y)
(b) increase with increase in y
(c) decrease with decrease in y
(d) depend on other considerations
(e) none of the above.
Ans: a

13.用于脆性涂层技术
(a) determining brittleness
(b) protecting metal against corrosion
(c) protecting metal against wear and tear
(d) experimental stress analysis
(e) non-destructive testing of metals.
Ans: d

14. Stress concentration is caused due to
(a) variation in properties of material from point to point in a member
(b) pitting at’points or areas at which loads on a member are applied
(c) abrupt change of section
(d) all of the above
(e) none of the above.
Ans: d

15. The endurance limit of a material with finished surface in comparison to rough surface is
(a) more
(b) less
(c) same
(d) more or less depending on quantum of load
(e) unpredictable.
Ans: a

16. Plastic flow in ductile materials
(a) increases the seriousness of static loading stress concentration
(b) lessens the seriousness of static loading stress concentration
(c) has no effect on it
(d) depends on other considerations
(e) none of the above.
Ans: b

17. The maximum stress due to stress concentration in a bar having circular transverse hole, as compared to its staticstress without hole will be
(a) same in both cases
(b) 2 times more
(c) 3 times more
(d) 4 times more
(e) unpredictable.
Ans: c

18. The fatigue life of a part can be improved by
(a) electroplating
(b) polishing
(c) coating
(d) shot peening
(e) heat treating.
Ans: d

19. Stress concentration in static loading is more serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: b 20. Stress concentration in cyclic loading is more serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: a

21. Endurance limit or fatigue limit is the maximum stress that a member can withstand for an infinite number of load applications without failure when subjected to
(a) dynamic loading
(b) static loading
(c) combined static and dynamic loading
(d) completely reversed loading
(e) all of the above.
Ans: d

22. Pick up wrong statement. Fatigue strength can be increased by
(a) cold working
(b) shot peening
(c) grinding and lapping surface
(d) hot working
(e) using gradual changes of section.
Ans: d

23. Which of the following is not correct procedure to increase the fatigue limit
(a) cold working
(b) shot peening
(c) surface decarburisation
(d) under-stressing
(e) all of the above.
Ans: c

24. Coaxing is the procedure of increasing
(a) metal strength by cycling
(b) metal hardness by surface treatment
(c) metal resistance to corrosion by coating
(d) fatigue limit by overstressing the metal by successively increasing loadings
(e) none of the above.
Ans: d

25. Which is correct statement ?
Stress concentration in static loading is
(a) very serious in brittle materials and less serious in ductile materials
(b) very serious in ductile materials and less serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: a

26. The notch angle of the Izod impact test specimen is
(a) 10°
(b) 20°
(c) 30°
(d) 45°
(e) 60°.
Ans: d

27. In Vicker’s hardness testing, the pyramid indentor apex is
(a) 40°
(b) 122°
(c) 136°
(d) 152°
(e) 161°.
Ans: c

28. Which is correct statement ?
Stress concentration in cyclic loading is
(a) very serious in brittle materials and less serious in ductile materials
(b) very serious in ductile materials and less serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: c

29. In testing a material for endurance strength, it is subjected to
(a) static load
(b) dynamic load
(c) impact load
(d) static as well as dynamic load
(e) completely reversed load.
Ans: e

30. If a material fails below its yield point, failure would be due to
(a) straining
(b) fatigue
(c) creep
(d) sudden loading
(e) impact loading.
Ans: b

31. The fatigue limit of a material
(a) is greatly decreased by poor surface conditions
(b) remains same irrespective of surface conditions
(c) depends mainly on core composition
(d) is dependent upon yield strength of material
(e) none of the above.
Ans: a

32. Cold working
(a) increases the fatigue strength
(b) decreases the fatigue strength
(c) has no influence on fatigue strength
(d) alone has no influence on fatigue strength
(e) none of the above.
Ans: a

33. Yield point in fatigue loading as compared to static loading is
(a) same
(b) higher
(c) lower
(d) depends on other factors
(e) none of the above.
Ans: c

34. Residual stress in materials
(a) acts when external load is applied
(b) becomes zero when external load is removed
(c) is independent of external loads
(d) is always harmful
(e) is always beneficial.
Ans: c

35. The building up of worn and uridersized parts, subjected to repeated loads by electroplating is
(a) best method
(b) extremely hazardous
(c) has no effect as regards fatigue strength
(d) cheapest method
(e) all of the above.
Ans: a

36. In nitrated parts, the origins of the fatigue cracks will occur at
(a) surface
(b) just below the surface
(c) within the core
(d) could occur anywhere
(e) none of the above.
Ans: e

37. Which process will increase the fatigue duration of parts ?
(a) finishing and polishing
(b) shot-peening
(c) decarburisation
(d) electroplating
(e) all of the above”.
Ans: b

38. Which is correct statement ?
(a) a member made of steel will generally be more rigid than a member of equal load-carrying ability made of cast iron
(b) a member made of cast iron will generally be. more rigid than a member of equal load carrying ability made of steel
(c) both will be equally rigid
(d) which one is rigid will depend on several other factors
(e) none of the above.
Ans: b

39. Resistance to fatigue of a material is measured by
(a) Young’s modulus
(b) coefficient of elasticity
(c) elastic limit
(d) ultimate tensile strength
(e) endurance limit.
Ans: e

Machine Design MCQ :Part 1|Part 2|Part 3|Part 4