Theory of Machines 1000+ MCQ with answer for GRE

1. For two governors A and B, the lift of sleeve of governor A is more than that of governor B, for a given fractional change in speed. It indicates that
A. Governor A is more sensitive than governor B
B. Governor B is more sensitive than governor A
C. Both governors A and B are equally sensitive
D. None of the above
Answer : A

2. The advantage of the piston valve over the slide valve is that in the former case
A. Wear is less
B. Power absorbed is less
C. Both wear and power absorbed are low
D. The pressure developed being high provides tight sealing
Answer : C

3. The size of a gear is usually specified by
A. Pressure angle
B. Circular pitch
C. Diametral pitch
D. Pitch circle diameter
Answer : D

4. The frictional torque transmitted in a flat pivot bearing, considering uniform wear, is (where ? = Coefficient of friction, W = Load over the bearing, and R = Radius of bearing surface)
A. (1/2) ? W R
B. (2/3) ? W R
C. (3/4) ? W R
D. ? W R
Answer : A

5. In an open pair, the two elements of a pair
A. Have a surface contact when in motion
B. Have a line or point contact when in motion
C. Are kept in contact by the action of external forces, when in motion
D. Are not held together mechanically
Answer : D

6. The displacement of the reciprocating roller follower, when it has contact with the straight flanks of the tangent cam, is given by (where r? = Minimum radius of the cam, r? = Radius of the roller follower, and ? = Angle turned by the cam from the beginning of the follower displacement)
A. (r? - r?) (1 - cos?)
B. (r? + r?) (1 + cos?)
C. (r? - r?) [(1 - cos?)/cos ?]
D. (r? + r?) [(1 - cos?)/cos ?]
Answer : D

7. When a shaking force is transmitted through the springs, damping becomes detrimental when the ratio of its frequency to the natural frequency is greater than
A. 0.25
B. 0.5
C. 1
D. 2
Answer : D

8. The periodic time of a compound pendulum is __________ when the distance between the point of suspension and the centre of gravity is equal to the radius of gyration of the body about its centre of gravity.
A. Zero
B. Minimum
C. Maximum
D. None of these
Answer : B

9. The method of obtaining different mechanisms by fixing in turn different links in a kinematic chain, is known as
A. Structure
B. Machine
C. Inversion
D. Compound mechanism
Answer : C

10. Open pairs are those which have
A. Point or line contact between the two elements when in motion
B. Surface contact between the two elements when in motion
C. Elements of pairs not held together mechanically
D. Two elements that permit relative motion
Answer : C

11. A spring controlled governor is found unstable. It can be made stable by
A. Increasing the spring stiffness
B. Decreasing the spring stiffness
C. Increasing the ball mass
D. Decreasing the ball mass
Answer : B

12. The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ?? rad/s in the clockwise direction and the link OB turns with angular velocity ?? rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)
A. ??.??.r
B. (?? - ??)r
C. (?? + ??)r
D. (?? - ??)2r
Answer : B

13. The Klein's diagram is useful to find
A. Displacement of various parts
B. Velocity of various parts
C. Acceleration of various parts
D. Angular acceleration of various parts
Answer : C

14. Which of the following mechanism is an approximate straight line motion mechanism?
A. Watt's mechanism
B. Grasshopper mechanism
C. Robert's mechanism
D. All of these
Answer : D

15. The power from the engine to the rear axle of an automobile is transmitted by means of
A. Worm and worm wheel
B. Spur gears
C. Bevel gears
D. Hooke's joint
Answer : D

16. The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a left turn. The effect of gyroscopic couple acting on it will be
A. To raise the bow and stern
B. To lower the bow and stern
C. To raise the bow and lower the stern
D. To raise the stern and lower the bow
Answer : C

17. In vibration isolation system, if ?/?n > 1, then the phase difference between the transmitted force and the disturbing force is
A. 0°
B. 90°
C. 180°
D. 270°
Answer : C

18. The maximum or minimum value of the swaying couple is
A. ± c.m.?².r
B. ± a (1 - c) m.?².r
C. ± (a/?2) (1 - c) m.?².r
D. ± 2a (1 - c) m.?².r
Answer : C

19. A point B on a rigid link AB moves with respect to A with angular velocity ? rad/s. The total acceleration of B with respect to A will be equal to
A. Vector sum of radial component and coriolis component
B. Vector sum of tangential component and coriolis component
C. Vector sum of radial component and tangential component
D. Vector difference of radial component and tangential component
Answer : C

20. The length of a simple pendulum which gives the same frequency as the compound pendulum, is
A. k_G + l?
B. k_G² + l?
C. (k_G² + l?²)/ l?
D. (k_G + l?²)/ l?
Answer : C

21. The equation of motion for a vibrating system with viscous damping is (d²x/dt²) + (c/m). (dx/dt) + (s/m). x = 0 If the roots of this equation are real, then the system will be
A. Over-damped
B. Under damped
C. Critically damped
D. Without vibrations
Answer : A

22. If the damping factor for a vibrating system is unity, then the system will be
A. Over damped
B. Under damped
C. Critically damped
D. Without vibrations
Answer : C

23. If two moving elements have surface contact in motion, such pair is known as
A. Sliding pair
B. Rolling pair
C. Surface pair
D. Higher pair
Answer : D

24. The radial distance from the top of a tooth to the bottom of a tooth in a meshing gear, is called
A. Dedendum
B. Addendum
C. Clearance
D. Working depth
Answer : C

25. When the speed of the engine fluctuates continuously above and below the mean speed, the governor is said to be
A. Stable
B. Unstable
C. Isochronous
D. Hunt
Answer : D

26. In a differential band brake as shown in the below figure, the drum rotates anticlockwise and the greater tension T? acts at A and smaller tension T? at B. Length OA is greater than length OB. In order to apply the brake, the force P at C should
A. Be zero
B. Act in upward direction
C. Act in downward direction
D. None of the above
Answer : C

27. In elliptical trammels
A. All four pairs are turning
B. Three pairs turning and one pair sliding
C. Two pairs turning and two pairs sliding
D. One pair turning and three pairs sliding
Answer : C

28. Coriolis component is encountered in
A. Quick return mechanism of shaper
B. Four bar chain mechanism
C. Slider crank mechanism
D. Both (A) and (C) above
Answer : A

29. In a steam engine, the distance by which the outer edge of the Dslide valve overlaps the steam port is called
A. Lead
B. Steam lap
C. Exhaust lap
D. None of these
Answer : B

30. The Whitworth quick return motion mechanism is formed in a slider crank chain when the
A. Coupler link is fixed
B. Longest link is a fixed link
C. Slider is a fixed link
D. Smallest link is a fixed link
Answer : A

31. The train value of a gear train is
A. Equal to velocity ratio of a gear train
B. Reciprocal of velocity ratio of a gear train
C. Always greater than unity
D. Always less than unity
Answer : B

32. A Hartnell governor has its controlling force (Fc) given by Fc = ar + b, where r is the radius of rotation and a and b are constants. The governor becomes isochronous when
A. a is +ve and b = 0
B. a = 0 and b is +ve
C. a is +ve and b is -ve
D. a is +ve and b is also +ve
Answer : A

33. A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will
A. Remain same as before
B. Become equal to 2R
C. Become equal to R/2
D. Become equal to R/4
Answer : A

34. The frictional torque transmitted by a disc or plate clutch is same as that of
A. Flat pivot bearing
B. Flat collar bearing
C. Conical pivot bearing
D. Truncated conical pivot bearing
Answer : B

35. In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if ?/?n is
A. Equal to 1
B. Equal to 2
C. Less than 2
D. Greater than 2
Answer : B

36. Effort of a governor is the
A. Mean force exerted at the sleeve for a given percentage change of speed
B. Workdone at the sleeve for maximum equilibrium speed
C. Mean force exerted at the sleeve for maximum equilibrium speed
D. None of the above
Answer : A

37. Critical damping is a function of
A. Mass and stiffness
B. Mass and damping coefficient
C. Mass and natural frequency
D. Damping coefficient and natural frequency
Answer : A

38. The lower pairs are __________ pairs.
A. Self-closed
B. Force-closed
C. Friction closed
D. None of these
Answer : A

39. The direction of linear velocity of any point on a link with respect to another point on the same link is
A. Parallel to the link joining the points
B. Perpendicular to the link joining the points
C. At 45° to the link joining the points
D. None of the above
Answer : B

40. The fundamental equation for correct steering is (where ? and ? = Angle through which the axis of the outer wheel and inner wheel turns respectively, c = Distance between the pivots of the front axles, and d = Wheel base)
A. sin? + sin? = b/c
B. cos? - sin? = c/b
C. cot? - cot? = c/b
D. tan? + cot? = b/c
Answer : C

41. The equivalent length of a simple pendulum which gives the same frequency as a compound pendulum is
A. h/(k_G² + h²)
B. (k_G² + h²)/h
C. h²/(k_G² + h²)
D. (k_G² + h²)/h²
Answer : B

42. Which of the following statement is correct for involute gears?
A. The interference is inherently absent.
B. The variation in centre distance of shafts increases radial force.
C. A convex flank is always in contact with concave flank.
D. The pressure angle is constant throughout the teeth engagement.
Answer : D

43. The Klein's method of construction for reciprocating engine mechanism
A. Is based on acceleration diagram
B. Is a simplified form of instantaneous center method
C. Utilises a quadrilateral similar to the diagram of mechanism for reciprocating engine
D. Enables determination of Carioles component
Answer : C

44. When the crank is at the outer dead centre, in a reciprocating steam engine, then the acceleration of the piston will be
A. ?² r {(n + 1)/n}
B. ?² r {(n - 1)/n}
C. ?² r {n/(n + 1)}
D. ?² r {n/(n - 1)}
Answer : B

45. The critical speed of a shaft in revolution per second is __________ as that of natural frequency of transverse vibration.
A. Same
B. Different
C. Unpredictable
D. None of these
Answer : A

46. The velocity of a flat-faced follower when it has contact with the flank of a circular arc cam, is given by
A. ?R cos?
B. ?(R - r?) cos?
C. ?(R - r?) sin?
D. ?r? sin?
Answer : C

47. TJIE horse power transmitted by a belt is dependent upon
A. Tension on tight side of belt
B. Tension on slack side of belt
C. Radius of pulley
D. All of the above
Answer : D

48. The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in
A. Transverse vibrations
B. Torsional vibrations
C. Longitudinal vibrations
D. All of these
Answer : A

49. The height of a Watt's governor is
A. Directly proportional to speed
B. Directly proportional to (speed)²
C. Inversely proportional to speed
D. Inversely proportional to (speed)²
Answer : D

50. Which of the following statements regarding laws governing the friction between dry surfaces are correct?
A. The friction force is dependent on the materials of the contact surfaces.
B. The friction force is directly proportional to the normal force.
C. The friction force is independent of me area of contact.
D. All of the above
Answer : D