Theory of Machines 1000+ MCQ with answer for UPSC CDS

1. The periodic time is given by (where ? = Angular velocity of the particle in rad/s)
A. ?/2?
B. 2?/?
C. ? × 2?
D. ?/?
Answer : B

2. For a kinematic chain to be considered as mechanism
A. Two links should be fixed
B. One link should be fixed
C. None of the links should be fixed
D. There is no such criterion
Answer : B

3. The coefficient of fluctuation of speed is __________ of maximum fluctuation of speed and the mean speed.
A. Sum
B. Difference
C. Product
D. Ratio
Answer : D

4. When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as a
A. Lower pair
B. Higher pair
C. Self-closed pair
D. Force-closed pair
Answer : A

5. The Coriolis component of acceleration acts
A. Along the sliding surface
B. Perpendicular to the sliding surface
C. At 45° to the sliding surface
D. Parallel to the sliding surface
Answer : B

6. If the number of links in a mechanism is equal to l, then the numbers of possible inversions are equal to
A. l - 2
B. l - 1
C. l
D. l + 1
Answer : C

7. The instantaneous centre of a rigid thin disc rolling on a plane rigid surface is located at
A. The centre of the disc
B. The point of contact
C. An infinite distance on the plane surface
D. The point on the circumference situated vertically opposite to the contact point
Answer : B

8. Which of the following is an open pair?
A. Journal bearing
B. Ball and Socket joint
C. Leave screw and nut
D. None of the above
Answer : C

9. A system in dynamic balance implies that
A. The system is critically damped
B. There is no critical speed in the system
C. The system is also statically balanced
D. There will absolutely no wear of bearings
Answer : C

10. Which type of gear train is used in clock mechanism to join hour hand and minute hand?
A. Simple gear train
B. Compound gear train
C. Reverted gear train
D. Epicyclic gear train
Answer : D

11. When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be
A. To move the ship towards starboard
B. To move the ship towards port side
C. To raise the bow and lower the stern
D. To raise the stern and lower the bow
Answer : A

12. The motion of a shaft in a circular hole is an example of
A. Completely constrained motion
B. Incompletely constrained motion
C. Successfully constrained motion
D. None of these
Answer : B

13. In a screw jack, the effort required to lower the load W is given by
A. P = W tan(? - ?)
B. P = W tan(? + ?)
C. P = W tan(? - ?)
D. P = W cos(? + ?)
Answer : C

14. 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

15. The partial balancing means
A. Balancing partially revolving masses
B. Balancing partially reciprocating masses
C. Best balancing of engines
D. All of these
Answer : B

16. When the two elements of a pair have __________ when in motion, it is said to a lower pair.
A. Line or point contact
B. Surface contact
C. Body contact
D. None of these
Answer : B

17. The condition for correct steering of a Davis steering gear is (where ? = Angle of inclination of the links to the vertical)
A. sin? = b/c
B. cos? = c/b
C. tan? = c/2b
D. cot? = c/2b
Answer : C

18. The centre of gravity of a coupler link in a four bar mechanism will experience
A. No acceleration
B. Only linear acceleration
C. Only angular acceleration
D. Both linear and angular acceleration
Answer : D

19. The gears are termed as medium velocity gears, if their peripheral velocity is
A. 1-3 m/s
B. 3-15 m/s
C. 15-30 m/s
D. 30-50 m/s
Answer : B

20. A circular bar moving in a round hole is an example of
A. Incompletely constrained motion
B. Partially constrained motion
C. Completely constrained motion
D. Successfully constrained motion
Answer : A

21. Inertia force acts
A. Perpendicular to the acceleration force
B. Along the direction of acceleration force
C. Opposite to the direction of acceleration force
D. None of the above
Answer : C

22. Which of the following statement is wrong?
A. The difference between the maximum and minimum energies is called maximum fluctuation of energy
B. The coefficient of fluctuation of speed is the ratio of maximum fluctuation of speed to the mean speed
C. The variations of energy above and below the mean resisting torque line is known as fluctuation of energy
D. None of the above
Answer : D

23. The frequency of oscillation of a torsional pendulum is
A. 2?k/r. ?(g/l)
B. r/2?k. ?(l/g)
C. 2?r/k. ?(g/l)
D. r/2?k. ?(g/l)
Answer : D

24. The frictional torque transmitted in a conical pivot bearing with assumption of uniform pressure is __________ as compared to uniform wear.
A. Less
B. More
C. Same
D. None of these
Answer : B

25. 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

26. Whirling speed of the shaft is the speed at which
A. Shaft tends to vibrate in longitudinal direction
B. Torsional vibrations occur
C. Shaft tends to vibrate vigorously in transverse direction
D. Combination of transverse and longitudinal vibration occurs
Answer : C

27. The Ackerman steering gear mechanism is preferred to the Davis steering gear mechanism, because
A. Whole of the mechanism in the Ackerman steering gear is on the back of the front wheels
B. The Ackerman steering gear consists of turning pairs
C. The Ackerman steering gear is most economical
D. Both (A) and (B)
Answer : D

28. The natural frequency of free longitudinal vibrations is equal to (where m = Mass of the body, s = Stiffness of the body, and ? = Static deflection of the body)
A. 1/2? × ?(s/m)
B. 1/2? × ?(g/?)
C. 0.4985/??
D. Any one of these
Answer : D

29. If D? and D? be the diameters of driver and driven pulleys, then belt speed is proportional to
A. D?/D?
B. D?/D?
C. D?.D?
D. D?
Answer : D

30. In a mechanism, usually one link is fixed. If the fixed link is changed in a kinematic chain, then relative motion of other links
A. Will remain same
B. Will change
C. Could change or remain unaltered depending on which link is fixed
D. Will not occur
Answer : A

31. The contact ratio is the ratio of
A. Length of pair of contact to the circular pitch
B. Length of arc of contact to the circular pitch
C. Length of arc of approach to the circular pitch
D. Length of arc of recess to the circular pitch
Answer : B

32. The balancing weights are introduced in planes parallel to the plane of rotation of the disturbing mass. To obtain complete dynamic balance, the minimum number of balancing weights to be introduced in different planes is
A. 1
B. 2
C. 3
D. 4
Answer : B

33. The acceleration of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by
A. ?². (r? r?). (1 - cos² ?)
B. ?². (r? + r?). (1 + cos² ?)
C. ?². (r? + r?). [(2 - cos² ?)/cos³ ?]
D. ?². (r? - r?). (1 - sin² ?)
Answer : C

34. Sensitiveness of the governor is defined as the ratio of the
A. Mean speed to the maximum equilibrium speed
B. Mean speed to the minimum equilibrium speed
C. Difference of the maximum and minimum equilibrium speeds to the mean speed
D. Sum of the maximum and minimum equilibrium speeds to the mean speed
Answer : C

35. The product of the diametral pitch and circular pitch is equal to
A. 1
B. 1/?
C. ?
D. 2 ?
Answer : C

36. Cylindrical cams can be classified as
A. Circular
B. Tangent
C. Reciprocating
D. None of the above
Answer : D

37. Klein's construction can be used when
A. Crank has a uniform angular velocity
B. Crank has non-uniform velocity
C. Crank has uniform angular acceleration
D. Crank has uniform angular velocity and angular acceleration
Answer : A

38. The secondary unbalanced force is __________ the primary unbalanced force.
A. One-half
B. Two-third
C. n times
D. 1/n times
Answer : D

39. The centre distance between two meshing involute gears is equal to
A. Sum of base circle radii/cos?
B. Difference of base circle radii/ cos?
C. Sum of pitch circle radii/ cos?
D. Difference of pitch circle radii/ cos?
Answer : A

40. A slider crank chain consists of following numbers of turning and sliding pairs
A. 1, 3
B. 2, 2
C. 3, 1
D. 4, 0
Answer : C

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

42. The relation between the controlling force (Fc) and radius of rotation (r) for a stable spring controlled governor is
A. F_c = ar + b
B. F_c = ar - b
C. Fc = ar
D. F_c = a/r + b
Answer : B

43. For an isochronous Hartnell governor (where r? and r? = Maximum and minimum radius of rotation of balls respectively, S? and S? = Maximum and minimum force exerted on the sleeve respectively, and M = Mass on the sleeve)
A. (m.g + S?)/(m.g + S?) = r?/r?
B. (m.g - S?)/(m.g - S?) = r?/r?
C. S?/S? = r?/r?
D. S?/S? = r?/r?
Answer : A

44. When the particles of a body moves perpendicular to its axis, then the body is said to have
A. Longitudinal vibration
B. Transverse vibration
C. Torsional vibration
D. None of these
Answer : B

45. The dynamic friction is the friction experienced by a body, when the body
A. Is in motion
B. Is at rest
C. Just begins to slide over the surface of the other body
D. None of the above
Answer : A

46. When the elements of a pair are kept in contact by the action of external forces, the pair is said to be a
A. Lower pair
B. Higher pair
C. Self-closed pair
D. Force-closed pair
Answer : D

47. The swaying couple is due to the
A. Primary unbalanced force
B. Secondary unbalanced force
C. Two cylinders of locomotive
D. Partial balancing
Answer : A

48. Cam size depends upon
A. Base circle
B. Pitch circle
C. Prime circle
D. Outer circle
Answer : A

49. The essential condition of placing the two masses, so that the system becomes dynamically equivalent, is (where l? and l? = Distance of two masses from the centre of gravity of the body, and kG = Radius of gyration of the body)
A. l? = k_G
B. l? = k_G
C. l?l? = k_G
D. l?l? = k_G²
Answer : D

50. In a Hartnell governor, the stiffness of the spring is given by (where S1 and S2 = Spring forces exerted on the sleeve at max. and min. radii of rotation, and h = Compression of the spring)
A. (S? + S?)/h
B. (S? - S?)/h
C. (S? + S?)/2h
D. (S? - S?)/2h
Answer : B