mcq unit 3

1. Shaft is rotating element which is use to transmit power from one point to another point.

A. TrueB. False C. Both a & bD. None of above

2. Axle is ……………

A. Non rotating machine elementB. Rotating machine elementC. Revolving elementD. Both a & b

3. Torsional formula is …………….

A. T/IP = ζ/r = GƟ/LB. IP/T = r/ ζ = L/GƟC. Tmax/ GƟ = r/ ζD. All of above

4. Find diameter of solid shaft to transmit 30 kW at 300 r.p.m. The ultimate shear stress for steel is 60 MPa.

A. 45 mmB. 55 mmC. 56 mmD. 65 mm


A. 41.109 mmB. 42.109 mmC. 52.109 mmD. 55 mm


A. 40 mmB. 50mmC. 60mmD. 70mm


A. 50 mmB. 73.80 mmC. 37.80 mmD. 79 mm

8. A cylindrical shaft made of steel is subjected to a bending moment of 20 kN-m and torsional moment of 40kN-m Find the equivalent twisting moment?

A. 44.72 kN-mB. 54.72 kN-mC. 55.72 kN-mD. 64.72 kN-m

9. A cylindrical shaft made of steel is subjected to a bending moment of 20kN-m and torsional moment of 40kN-m Find the equivalent twisting moment and equivalent bending moment?

A. 55 kN-m and 67 kN-mB. 44.72 kN-m and 32.36 kN-mC. 55.72 kN-m and 42.72 kN-mD. 66.84 kN-m and 45.89 kN-m


A. 55.455 kN-m and 56.455 kN-mB. 66.566 kN-m and 65.678 kN-mC. 63.245 kN-m and 41.622 kN-mD. 73.245 kN-m and 41.245 kN-m


A. 68.30 kN-m and 54.15 kN-mB. 58.30 kN-m and 44.15 kN-mC. 78.30 kN-m and 64.15 kN-mD. 88.30 kN-m and 74.15 kN-m

11. A cylindrical shaft made of steel is subjected to a bending moment of 30kN-m and torsional moment of 50kN-m Find the equivalent twisting moment?

A. 58.30 kN-m

B. 68.30 kN-mC. 78.30 kN-mD. None of above

12. A cylindrical shaft made of steel is subjected to a bending moment of 50kN-m and torsional moment of 70kN-m Find the equivalent twisting moment?

A. 55.08 kN-mB. 86.023 kN-mC. 96.55 kN-mD. 76.023 kN-m

13. A shaft diameter is required to transmit 100 kW power at 240 r.p.m.

If maximum permissible 15d length is 10 , diameter of the shaft?

A. 76.46 mmB. 86.55 mmC. 96.55 mmD. None of above

14. Key is device use for connecting two machine parts for preventing relative motion of rotation with respect to each other.

A. True B. FalseC. NoneD. All option wrong

15.sunk keys are designed to fit in sunk keyway which is…………..to the axis of the shaft.

A. ParallelB. SeriesC. InclineD. All of above

16. Sunk key has ………………….cross- section

A. Square B. RectangularC. ParallelD. Cubic

17. Parallel sunk key is a ……………… key.

A. Taper B. Taper lessC. RoundD. None of above

18. According Moore formula the shaft strength factor is given by……….

A. e =1-0.3(w/d)-1.1(h/d)B. e =1-0.2(w/d)-1.1(h/d)C. e =1-0.5(w/d)-1.1(h/d)D. e =1-0.7(w/d)-0.1(h/d)

19. Shear strength of the key ……………..

A. Tk =ζk (w/2)( l/2) (d/2)B. σTk =ζk w l (d/2)C. Tk =ζk l (d/2)D. Tk =ζk w (d/2)

20. Crushing strength of key………..

A. T= σc× (l/2) × (t/2) × (d/2)B. T= (σc/2)× l × (t/2) × (d/2)C. T= σc× l × (t/2) × (d/2)D. None of above

21. Ultimate permissible stress in tension…………….

A. σu /F.O.S.B. T= σc× l × (t/2) × (d/2)C. σu /F.O.S. (d/2)D. none of above

22. A shaft diameter is 80 mm transmits power at maximum shear stress of 60 MPa. Find length at a 20 mm wide square key to mount a pulley on shaft so that normal and shear stress not exceed 80 MPa and 40 MPa.

A. 120mmB. 188.43mmC. 260mmD. 138.34mm

23. A shaft diameter is 80 mm transmits power at maximum shear stress of 60 MPa. Find power transmission by shaft at a 20 mm wide square key to mount a pulley on shaft so that normal and shear stress not exceed 80 MPa and 40 MPa.

A. 8.03 kN-mB. 6.03 kN-mC. 7.05 kN-m

D. 6.73

24. Usually assumed that the strength of the keyed shaft is………….

A. 67%B. 77%C. 75%D. 8%

25.In case of keyway is too long and key is of sliding type, then the angle of twist is increased In ratio kƟ as given by……………….

A. kƟ =1.5+0.3(w/d)+0.7(h/d)B. kƟ =1+0.4(w/d)+0.7(h/d)C. kƟ =2+0.5(w/d)+0.7(h/d)D. kƟ =0.7(w/d)+0.7(h/d

26. Design a clamp coupling to transmit 30kW at 100r.p.m. calculate the torque transmitted by shaft?

A. 5682×103 N-mmB. 8265×103 N-mmC. 2568×103 N-mmD. 2865×103 N-mm

27. Design a clamp coupling to transmit 40kW at 100r.p.m. calculate the torque transmitted by shaft?

A. 310×103 N-mmB. 381×103 N-mmC. 3810×103 N-mmD. 3780×103 N-mm

28. Designs a clamp coupling to transmit 40kW at 150r.p.m. calculate the torque transmitted by shaft?

A. 2546.47 N-mmB. 2546.47×103 N-mmC. 2645.47×103 N-mmD. 2456.47×103 N-mm


A. 2291.83×103 N-mmB. 2291.83 N-mC. 2921.83 N-mD. Both a & b

30. Crank shaft is an example of………………….

A. Machine shaft B. TRANSMISSAION shaftC. Rotating shaftD. None of above

31. Shaft is subjected to………..

A. Twisting momentB. Bending momentC. Both a & bD. None of above

32. A solid shaft is transmitting 1MW at 240r.p.m. Determine torque transmitted by the shaft?

A. 38764 N-mmB. 39784 N-mmC. 39784×103 N-mmD. 37694×103 N-mm

33. A line shaft rotating at 200r.p.m. is to transmit 20kW. The shaft may be assumed to be made of mild steel with allowable shear stress 42MPa determine diameter of shaft?

A. 50 mmB. 60mmC. 70mmD. None of above

34. Coupling is used to join two shafts so as to get longer shaft greater than …………… length

A. 8 m.B. 7 m.C. 9 m.D. 6 m.

35. The torsional strength is given by……….

A. T/IP ≠ ζ max /rB. T/IP = ζ max /rC. T/IP ≥ ζ max /rD. None of above

36. In bending or flexural strength formula M/I = σ b max /y at σ max at

y =………..

A. DB. D/2C. D/3D. D2/2

37. In case of square sunk key width W = …………….

A. d/4B. d/2C. d/3D. d/6

38. If shaft transmit torque T in clockwise direction, then tangential force F at the shaft diameter is ……………

A. F = T/DB. F = 3T/D C. F = 2T/D D. F = T/2D

39. In case of square key, crushing stress is exactly ……………. Of shearing stress.

A. ThriceB. Four timesC. TwiceD. Eight times

40. Rigid coupling are used to connect …………… shaft.

A. CollinearB. Non collinearC. Parallel

D. Antiparallel

41. sleeve coupling also called as ……..

A. ClampB. FlangeC. MuffD. Rigid

42. ……………. Is/ are flexible coupling.

1. Bushed pin 2.Bucked pin 3.universal 4.Oddham

A. Only 1B. 1,3&4C. 2,3 and 4D. All the above

43. Clamp coupling is ……………….. Coupling

A. RigidB. FlexibleC. FlangeD. None

44.In flange coupling the forces of flanges are …………. to axis of shaft.

A. Right angleB. Inclined to 450

C. Inclined to 600

D. At 1800

45. If diameter of flange coupling is 160mm then no. of bolts needed are

A. 2B. 3C. 4D. 6


A. 1765.85N-mB. 1909.85N-mC. 1678.85N-mD. 1678.85N-m

46. What is equation of equivalent twisting moment in shaft is combined with twisting moment and bending moment?

A. M2 + T2

B. (M2 + T2)1/3

C. (M2 + T2)1/2

D. M+D

47. A shaft is required to torque is 2883 N-m. The supported length of shaft is 3 m its force acts 1000N and distance of 1 m from end respectively find twisting moment?

A. 3051.50 N-mB. 3541.50 N-mC. 3678.50 N-mD. 3681.50 N-m

48. The shaft is required maximum bending moment 85N-m and its dia meter is 15 cm what is a bending stress?

A. 25.65 N-mB. 25.65 kN-mC. 21.65kN-mD. 20.65 N-m

49. According to Rankin theory d3 =……………..

A. d3 =32Me/π σb

B. d3 =42Me/σb

C. d3 =62Me/πσb

D. d3 =12Me/πσb

50. A hollow steel shaft maximum bend moment is 65 N-m. Its circumference of circle is 120 mm thickness of shaft 9.28 mm what is bending stress?

A. 125kN-mB. 0.12511×105kN-mC. 0.125N-mD. 0.125×108kN-m

51. If in case of square key width is equal to thickness then shear in…………..of crushing stress.

A. TwiceB. HalvedC. QuadrupledD. Eight times

52. A hollow shaft is 2m long and has outer and inner diameter 200 mm and 150 mm respectively. If maximum shear stress is limited to 50 MPa hence find maximum power that can be transmitted at 200 r.p.m.

A. 5.368kN-mB. 53.68 kN-mC. 53.68 MN-mD. 53.68 N-m

53. If a shaft is simply supported beam with central point load then maximum B.M is M =………….

A. WL/2B. WL/4C. 2WL/3D. WL/6

54. It is good shaft coupling follows………..

A. perfect alignment B. connected or disconnectedC. Both a & bD. None

55. Length of muff coupling ……….

A. 3.5dB. 0.35dC. 35dD. 0.035d

mcq unit 3

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