Quiznetik

Mechatronics | Set 1

1. Which of the following is incorrect regarding inertia force?

Correct : D. same direction as of accelerating force

2. Inertia torque acts in the same direction as the accelerating couple?

Correct : B. false

3. If a force has a line of action at a distance h from the centre of gravity, then the value of h is given by

Correct : A. i. α/f

4. D-Alembert’s principle is used for which of the following?

Correct : B. change dynamic problem to static problem

5. 2 D ALEMBERT'S PRINCIPLE - DYNAMIC ANALYSIS IN RECIPROCATING ENGINES

Correct : A. reversed effective force

6. A body remains in equilibrium if

Correct : B. inertia force is applied in the direction opposite to the resultant force

7. Inertia force and the reversed effective force are the same.

Correct : A. true

8. In the following picture the G is the center of gravity, the quantity h is known as the “offset”. I is the moment of inertia and k is the radius of gyration. Offset’s value is given by?

Correct : A. i.α/f

9. Considering a four bar chain with each link having linear and angular acceleration, applying D-Alembert’s principle will never result in which of the following member?

Correct : A. 2- force member

10. Piston effort acts along the line of stroke.

Correct : A. true

11. In a horizontal engine, reciprocating parts are accelerated when the piston moves from

Correct : A. tdc to bdc

12. In a horizontal engine, reciprocating parts are retarded when the piston moves from

Correct : B. bdc to tdc

13. When the piston is accelerated, the piston effort is given by which of the following the equation?

Correct : B. f(l) + f(i)

14. In the presence of frictional resistance, the expression for piston effort is

Correct : C. f(l) ± f(i) – r(f)

15. Crank effort is the product of crank pin radius and

Correct : B. crankpin effort

16. In a horizontal engine, the weight of the reciprocating parts also add/subtract to the piston effort.

Correct : B. false

17. For the given data of an Internal combustion engine : Mass of parts = 180 kg bore = 175 mm, length of stroke = 200 mm, engine speed = 500 r.p.m., length of connecting rod = 400 mm and crank angle = 60° from T.D.C, find the inertia force.

Correct : C. 18.53 n

18. 45 N/mm2. The connecting rod length between centres is 1.2 m and the cylinder bore is 0.5 m. If the engine runs at 250 r.p.m. and if the effect of piston rod diameter is neglected, calculate the net load on piston.

Correct : D. 88357 n

19. Multi cylinder engines are usually placed at an equal inclination to each other.

Correct : A. true

20. For a multicylinder engine, the coefficient of fluctuation of speed would vary with

Correct : B. remains unaffected

21. In the turning moment diagram of a multicylinder engine, the work done during exhaust stroke is by

Correct : B. on the gases

22. For a 4 cylinder engine, when the pressure inside the cylinders exceeds the atmospheric pressure then.

Correct : A. work is done by the gases

23. In a punching press, which of the following quantity is constant?

Correct : B. torque

24. In a punching press, load is 0 at the time of punching.

Correct : B. false

25. The maximum shear force required for punching depends on

Correct : A. sheared area

26. A machine punching 38 mm holes in 32 mm thick plate requires 7 N-m of energy per sq. mm of sheared area, find the maximum shear force required.

Correct : A. 26.7 kn

27. The relation between stroke punch s and radius of crank r is

Correct : B. s=2r

28. If the stroke punch is 100mm, find the radius of the crank in mm.

Correct : C. 50

29. Energy during actual punching operation is same as the energy supplied by the motor.

Correct : B. false

30. The balance energy required for punching is supplied by the flywheel by

Correct : B. decrease in its kinetic energy

31. When the length of the connecting rod is unknown then the value (θ2 –θ1)/2π is equal to

Correct : B. t/2s

32. The size of a cam depends upon

Correct : A. base circle

33. The angle between the direction of the follower motion and a normal to the pitch curve is called

Correct : D. pressure angle

34. The cam follower generally used in automobile engines is

Correct : C. spherical faced follower

35. The cam follower extensively used in air- craft engines is

Correct : D. roller follower

36. In a radial cam, the follower moves

Correct : A. in a direction perpendicular to the cam axis

37. A radial follower is one

Correct : A. that reciprocates in the guides

38. Ofset is provided to a cam follower mechanism to

Correct : A. minimise the side thrust

39. For low and moderate speed engines, the cam follower should move with

Correct : B. simple harmonic motion

40. For high speed engines, the cam follower should move with

Correct : D. cycloidal motion

41. Which of the following displacement diagrams should be chosen for better dynamic performance of a cam-follower mechanism ?

Correct : C. cycloidal motion

42. The displacement of a flat faced follower when it has contact with the flank of a circular arc cam, is given by

Correct : C. (r-r1)(1-cosθ)

43. The retardation of a flat faced follower when it has contact at the apex of the nose of a circular arc cam, is given by

Correct : A. ω2×oq

44. Centre of masses of the system lies on the axis of rotation.

Correct : D. 1, 3 and 4 only

45. Which of the following statements is correct about the balancing of a mechanical system?

Correct : C. both static as well as dynamic balance have to be achieved separately

46. In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large in order to

Correct : B. minimize the effect of secondary forces

47. Multi-cylinder engines are desirable because

Correct : C. both (a) and (b)

48. Secondary forces in reciprocating mass on engine frame are

Correct : B. twice the frequency as of primary forces

49. Work produced by the 4-stroke engine is less because

Correct : A. one power stroke per 2 revolutions

50. When the work is done on the gases, which of the following effect is observed on the turning moment diagram?

Correct : A. formation of negative loop

51. Compression stroke results in

Correct : A. formation of negative loop

52. 4 strokes engine have a lower thermal efficiency than 2 stroke engine.

Correct : B. false

53. 3 BALANCING MACHINES-FIELD BALANCING OF DISCS AND ROTORS.

Correct : D. inertia forces

54. Balancing of single rotating mass by balancing masses in same plane and in different planes cannot take place.

Correct : B. false

55. Which of the following is true for centrifugal force causing unbalance?

Correct : A. direction changes with rotation

56. In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of the rotor lies

Correct : B. on the axis of the shaft

57. If the unbalanced system is not set right then.

Correct : A. static forces develop

58. What is not the effect of unbalanced forces?

Correct : D. violation of conservation of mass principle

59. The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in

Correct : A. transverse vibrations

60. In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be

Correct : C. greater than unity

61. The accelerometer is used as a transducer to measure earthquake in Richter scale. Its design is based on the principle that

Correct : C. its natural frequency is equal to the frequency of vibration

62. Critical speed is expressed as

Correct : D. natural frequency of the shaft

63. The first critical speed of an automobile running on a sinusoidal road is calculated by (modeling it as a single degree of freedom system)

Correct : A. resonance

64. The natural frequency of a spring-mass system on earth is ωn. The natural frequency of this system on the moon (gmoon = gearth/6) is

Correct : A. ωn

65. 6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural frequency (fn), respectively, are

Correct : A. 0.471 and 1.19 hz

66. 5 m/s.

Correct : C. 3.49

67. Which of the following expression represent the angular acceleration α of the connecting rod?

Correct : A. −ω2 . sin θ/n

68. While calculating angular acceleration of the connecting rod, sin2(θ) term is neglected.

Correct : A. true

69. In a slider crank mechanism, the length of the crank and connecting rod are 180 mm and 540 mm respectively. The crank position is 45° from inner dead centre. The crank shaft speed is 450 r.p.m. (clockwise), calculate angular velocity of the connecting rod in rad/s.

Correct : B. 11.1

70. When a body is subjected to transverse vibrations, the stress induced in a body will be

Correct : B. bending stress

71. Longitudinal vibrations are said to occur when the particles of a body moves

Correct : B. parallel to its axis

72. When a body is subjected to transverse vibrations, the stress induced in a body will be

Correct : B. tensile stress

73. The factor which affects the critical speed of a shaft is

Correct : D. all of the mentioned

74. The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as

Correct : D. magnification factor

75. Which of the following systems produce a vibration in the foundation?

Correct : A. unbalanced machine

76. When a periodic disturbing force is applied to a machine, the force is transmitted to the foundation by the means of spring.

Correct : A. true

77. Which of the following is a type of transmitted force to the foundation?

Correct : A. damping force

78. If the damper is not provided and the system is in resonance, which of the following is the correct isolation factor?

Correct : D. infinity

79. If isolation factor is negative, then what is the phase difference between transmitted and disturbing force?

Correct : A. 180°

80. Which of the following is true regarding Ɛ>1?

Correct : A. transmitted force is greater than applied force

81. Isolation factor is twice the transmissibility ratio.

Correct : B. false

82. The height of a Watt’s governor is

Correct : D. inversely proportional to (speed)

83. A Watt’s governor can work satisfactorily at speeds from

Correct : C. 100 to 200 r.p.m

84. When the sleeve of a Porter governor moves downwards, the governor speed

Correct : B. decreases

85. In a Porter governor, the balls are attached to the extension of lower links.

Correct : A. true

86. A Hartnell governor is a

Correct : C. spring loaded governor

87. A Watt’s governor is a spring loaded governor.

Correct : B. false

88. Which of the following is a pendulum type governor?

Correct : A. watt’s governor

89. A disc is a spinning with an angular velocity ω rad/s about the axis of spin. The couple applied to the disc causing precession will be

Correct : D. iωωp

90. The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be

Correct : C. to raise the nose and dip of the tail

91. The steering of a ship means

Correct : B. turning of a complete ship in a curve towards right or left, while it moves forward

92. The rolling of a complete ship side-ways is known as pitching of a ship.

Correct : B. false

93. The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a right turn. The effect of gyroscopic couple acting on it will be to raise the stern and lower the bow.

Correct : A. true

94. The pitching of a ship is assumed to take place with simple harmonic motion.

Correct : A. true

95. Power is transmitted by an electric motor to a machine by using a belt drive. The tensions on the tight and slack side of the belt are 2200 N and 1000 N respectively and diameter of the pulley is 600 mm. If speed of the motor is 1500 r.p.m, find the power transmitted.

Correct : B. 56.548 kw

96. 6 x 10 = 6 rad/s.

Correct : A. 2.055 m

97. Calculate the work done per minute by a punch tool making 20 working strokes per min when a 30 mm diametre hole is punched in 5 mm thick plate with ultimate shear strength og 450 Mpa in each stroke.

Correct : A. 10.69 knm

98. In latitude 25.0 S, SA (spin axis) of a FG (free gyro) is in position S40E and horizontal. Find the tilt after 6 hours.

Correct : A. 61.16 up

99. The steering of a ship means

Correct : B. turning of a complete ship in a curve towards right r left, while it moves forward

100. When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be

Correct : A. to move the ship towards starboard