JEE Main - Machine Design 1000+ MCQ [Solved] PDF Download

1. Wire ropes as compared to cotton ropes
A. Are lighter in weight
B. Offer silent operation
C. Can withstand shock loads
D. All of these
Answer : D

2. In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to the teeth, is called
A. Normal pitch
B. Axial pitch
C. Diametral pitch
D. Module
Answer : A

3. When the connected members are very yielding (soft gasket) as compared to the bolt, then the resultant load on the bolt will be equal to the
A. Initial tension
B. External load applied
C. Sum of the initial tension and external load applied
D. Initial tension or external load, whichever is greater
Answer : C

4. For tight leakage joints, following type of thread is best suited
A. Metric
B. Buttress
C. Square
D. NPT (national pipe threads)
Answer : D

5. When the length of the journal is equal to the diameter of the journal, then the bearing is said to be a
A. Short bearing
B. Long bearing
C. Medium bearing
D. Square bearing
Answer : D

6. The connecting rod bolts are tightened up with initial tension greater than the external load so that
A. Joint may not open up
B. Bolts are weakest elements
C. The resultant load on the bolt would not be affected by the external cyclic load
D. Bolts will not loosen during service
Answer : C

7. When a close coiled helical spring is compressed, its wire is subjected to
A. Tension
B. Shear
C. Compression
D. All of the above
Answer : A

8. When the shaft rotates in anticlockwise direction at slow speed in a bearing, it will
A. Have contact at the bottom most of the bearing
B. Move towards right of the bearing making no metal to metal contact
C. Move towards right of the bearing making the metal to metal contact
D. Move towards left of the bearing making metal to metal contact
Answer : D

9. The lower deviation is the algebraic difference between the
A. Actual size and the corresponding basic size
B. Maximum limit and the basic size
C. Minimum limit and the basic size
D. None of the above
Answer : C

10. The spring mostly used in gramophones is
A. Helical spring
B. Conical spring
C. Flat spiral spring
D. Volute spring
Answer : C

11. The stress in the threaded part of the bolt will be __________ as compared to the shank.
A. Same
B. Higher
C. Lower
D. None of these
Answer : B

12. Which of the following statement is wrong?
A. A key is used as a temporary fastening
B. A key is subjected to tensile stresses
C. A key is always inserted parallel to the axis of the shaft
D. A key prevents relative motion between the shaft and boss of the pulley
Answer : B

13. 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
Answer : C

14. In worm, gears, pitch lead angle is
A. Half the angle between two inclined faces in axial plane
B. The angle between the tangent to the pitch helix and the plane of rotation
C. The angle between the tangent to the pitch helix and an element of the cylinder
D. None of the above
Answer : B

15. Gear box is used
A. To produce torque
B. For speed reduction
C. To obtain variable speeds
D. To increase efficiency of system
Answer : C

16. The crest diameter of a screw thread is same as
A. Major diameter
B. Minor diameter
C. Pitch diameter
D. Core diameter
Answer : A

17. The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is
A. Larger
B. Smaller
C. Equal
D. Larger/smaller depending on diameter of spring coil
Answer : A

18. In block brakes, the ratio of shoe width to wheel diameter is taken between
A. 0.1 and 0.25
B. 0.25 and 0.50
C. 0.50 and 0.75
D. 0.75 and 1
Answer : B

19. The belt slip occurs due to
A. Heavy load
B. Loose belt
C. Driving pulley too small
D. Any one of the above
Answer : D

20. The pitch of threads on a Jock nut in comparison to pitch of nut is
A. Same
B. Coarser
C. Finer
D. Very fine
Answer : A

21. The constant factor in case of R10 series of preferred numbers is
A. 1.06
B. 1.12
C. 1.26
D. 1.58
Answer : C

22. When a material is subjected to fatigue loading, the ratio of the endurance limit to the ultimate tensile strength is
A. 0.20
B. 0.35
C. 0.50
D. 0.65
Answer : C

23. According to I.B.R., the factor of safety of riveted joint should not be less than
A. 1
B. 2
C. 3
D. 4
Answer : D

24. In helical gears, the right hand helixes on one gear will mesh __________ helixes on the other gear.
A. Right hand
B. Left hand
C. Both A and B
D. None of these
Answer : B

25. Fabric belts are used in industrial applications because
A. They are cheap
B. They can work at high temperature
C. They are unaffected by moisture and humidity
D. None of the above
Answer : A

26. During hot working of metals,
A. Porosity of the metal is largely eliminated
B. Grain structure of the metal is refined
C. Mechanical properties are improved due of refinement of grains
D. All of the above
Answer : D

27. Elastic nut is a locking device in which
A. One small nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
B. A slot is cut partly in middle of nut and then slot reduced by tightening a screw
C. Hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is stewed on the bolt causing a tight grip
D. Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at other end
Answer : C

28. Which of the following material has the maximum ductility?
A. Copper
B. Mild steel
C. Aluminium
D. Zinc
Answer : B

29. When the bearing is subjected to large fluctuations of load and heavy impacts, the bearing characteristic number should be _________ the bearing modulus.
A. 10 times
B. 5 times
C. 15 times
D. 20 times
Answer : C

30. The maximum efficiency of a square threaded screw is
A. (1 - sin?)/ (1 + sin?)
B. (1 + sin?)/ (1 - sin?)
C. (1 - sin?)/ (1 + cos?)
D. (1 + cos?)/ (1 - sin?)
Answer : A

31. When two nonintersecting and non-coplanar shafts are connected by gears, the arrangement is known as
A. Spur gearing
B. Helical gearing
C. Bevel gearing
D. Spiral gearing
Answer : D

32. In the levers of third type, the mechanical advantage is __________ one.
A. Less than
B. Equal to
C. More than
D. None of these
Answer : A

33. The shock resistance of steel is increased by adding
A. Nickel
B. Chromium
C. Nickel and chromium
D. Cobalt and molybdenum
Answer : C

34. In order to have a connecting rod equally strong in buckling about X-axis and Y-axis, the moment of inertia about X-axis should be __________ the moment of inertia about Y-axis.
A. Equal to
B. Twice
C. Three times
D. Four times
Answer : D

35. When a nut is tightened by placing a washer below it, the bolt will be subjected to following type of loads
A. Compression
B. Tension
C. Shear
D. Combined loads
Answer : B

36. The washer is generally specified by its
A. Outer diameter
B. Hole diameter
C. Thickness
D. Mean diameter
Answer : B

37. For general industrial machinery, the ratio of the length of journal to its diameter is taken as
A. 0.5 to 1
B. 1 to 2
C. 3 to 5
D. 5 to 10
Answer : B

38. The endurance limit in shear of carbon steel can be obtained by multiplying the endurance limit in flexure by a factor of
A. 0.45
B. 0.55
C. 0.65
D. 0.75
Answer : D

39. The helix angle for single helical gears ranges from
A. 10° to 15°
B. 15° to 20°
C. 20° to 35°
D. 35° to 50°
Answer : C

40. In case of pressure vessels having closed ends, the fluid pressure induces
A. Longitudinal stress
B. Shear stress
C. Circumferential stress
D. None of these
Answer : D

41. The connecting rod bolts are tightened up so that tightening stress
A. Is just sufficient to hold parts together
B. Approaches yield point
C. Is 50% of yield point
D. Is about yield point divided by safety factor
Answer : B

42. Which of the following cotter joint will be used to connect strap end of a connecting rod?
A. Spigot and socket cotter joint
B. Sleeve and cotter joint
C. Gib and cotter joint
D. Any one of these
Answer : C

43. According to Indian standard specifications, 100 H6/g5 means that the
A. Basic size is 100 mm
B. Actual size is 100 mm
C. Difference between the actual size and basic size is 100 mm
D. None of the above
Answer : A

44. Lewis equation in gears is used to find the
A. Tensile stress in bending
B. Shear stress
C. Compressive stress in bending
D. Fatigue stress
Answer : C

45. The objective of caulking in a riveted joint is to make the joint
A. Free from corrosion
B. Stronger in tension
C. Free from stress
D. Leak-proof
Answer : D

46. A steel containing __________ 0.8% carbon is known as hypoeutectoid steel.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : B

47. If a material fails below its yield point, failure would be due to
A. Straining
B. Fatigue
C. Creep
D. Sudden loading
Answer : B

48. The smallest diameter of an external or internal screw thread is known as
A. Minor diameter
B. Major diameter
C. Pitch diameter
D. None of these
Answer : A

49. The flank of the tooth is the
A. Surface of the top of the tooth
B. Surface of the tooth above the pitch surface
C. Width of the tooth measured along the pitch circle
D. Surface of the tooth below the pitch surface
Answer : D

50. The dedendum is the radial distance from the
A. Pitch circle to the top of a tooth
B. Pitch circle to the bottom of a tooth
C. Top of a tooth to the bottom of a tooth
D. Addendum circle to the clearance circle
Answer : B