Theory of Machines 1000+ MCQ with answer for UPSC CSE

1. The moment on the pulley which produces rotation is called
A. Inertia
B. Momentum
C. Moment of momentum
D. Torque
Answer : D

2. When two links are connected by a pin joint, their instantaneous centre lies
A. On their point of contact
B. At the centre of curvature
C. At the centre of circle
D. At the pin joint
Answer : D

3. When a body is subjected to transverse vibrations, the stress induced in a body will be
A. Shear stress
B. Bending stress
C. Tensile stress
D. Compressive stress
Answer : B

4. 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

5. A spring controlled governor is said to be isochronous when the controlling force
A. Increases as the radius of rotation decreases
B. Increases as the radius of rotation increases
C. Decreases as the radius of rotation increases
D. Remain constant for all radii of rotation
Answer : D

6. In a shaper mechanism, the Coriolis component of acceleration will
A. Not exist
B. Exist
C. Depend on position of crank
D. None of the above
Answer : B

7. When the pitching of a ship is __________ the effect of gyroscopic couple acting on it will be to move the ship towards port side.
A. Upward
B. Downward
C. Forward
D. Backward
Answer : B

8. 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

9. When the sleeve of a Porter governor moves downwards, the governor speed
A. Increases
B. Decreases
C. Remain unaffected
D. First increases and then decreases
Answer : B

10. 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

11. The example of rolling pair is
A. Bolt and nut
B. Lead screw of a lathe
C. Ball and socket joint
D. Ball bearing and roller bearing
Answer : D

12. In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where ? = Coefficient of friction between the blocks and the drum, ? = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)
A. T?/T? = ?. ?. n
B. T?/T? = [(1 - ? tan?)/(1 + ? tan?)]n
C. T?/T? = (? ?)n
D. T?/T? = [(1 + ? tan?)/(1 - ? tan?)]n
Answer : D

13. The efficiency of a screw jack is maximum, when (where ? = Helix angle, and ? = Angle of friction)
A. ? = 45° + ?/2
B. ? = 45° - ?/2
C. ? = 90° + ?
D. ? = 90° - ?
Answer : B

14. The balancing of a rigid rotor can be achieved by appropriately placing balancing masses in
A. A single plane
B. Two planes
C. Three planes
D. Four planes
Answer : B

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

16. 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

17. When a point moves along a straight line, its acceleration will have
A. Radial component only
B. Tangential component only
C. Coriolis component only
D. Radial and tangential components both
Answer : B

18. The centrifugal tension in belts
A. Increases power transmitted
B. Decreases power transmitted
C. Have no effect on power transmitted
D. Increases power transmitted upto a certain speed and then decreases
Answer : C

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

20. Which of the following is a higher pair?
A. Turning pair
B. Screw pair
C. Belt and pulley
D. None of the above
Answer : C

21. The velocity of the rubbing surface __________ with the distance from the axis of the bearing.
A. Increases
B. Decreases
C. Remain same
D. None of these
Answer : A

22. The frictional torque transmitted in a flat pivot bearing, considering uniform pressure, 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 : B

23. 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

24. To obviate axial thrust, following gear drive is used
A. Double helical gears having opposite teeth
B. Double helical gears having identical teeth
C. Single helical gear in which one of the teeth of helix angle a is more
D. Mutter gears
Answer : A

25. Which of the following is an example of sliding pair?
A. Piston and cylinder of a reciprocating steam engine
B. Shaft with collars at both ends fitted into a circular hole
C. Lead screw of a lathe with nut
D. Ball and a socket joint
Answer : A

26. The maximum efficiency of a screw jack is
A. (1 - sin?)/(1 + sin?)
B. (1 + sin?)/(1 - sin?)
C. (1 - tan?)/(1 + tan?)
D. (1 + tan?)/(1 - tan?)
Answer : A

27. A kinematic chain requires at least
A. 2 links and 3 turning pairs
B. 3 links and 4 turning pairs
C. 4 links and 4 turning pairs
D. 5 links and 4 turning pairs
Answer : C

28. 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

29. With usual notations for different parameters involved, the maximum fluctuations of energy for a flywheel is given by
A. 2EC_S
B. EC_S/2
C. 2EC_S²
D. 2E²C_S
Answer : A

30. Two systems shall be dynamically equivalent when
A. The mass of two are same
B. C.G. of two coincides
C. M.I. of two about an axis through e.g. is equal
D. All of the above
Answer : D

31. An eccentric sheave pivoted at one point rotates and transmits oscillatory motion to a link whose one end is pivoted and other end is connected to it. This mechanism has
A. 2 links
B. 3 links
C. 4 links
D. 5 links
Answer : C

32. The sense of Coriolis component is such that it
A. Leads the sliding velocity vector by 90°
B. Lags the sliding velocity vector by 90°
C. Is along the sliding velocity vector
D. Leads the sliding velocity vector by 180°
Answer : A

33. For S.H.M. cam, the acceleration of the follower at the ends of the stroke and aimed stroke respectively, is
A. Maximum and zero
B. Zero and maximum
C. Minimum and maximum
D. Zero and minimum
Answer : A

34. 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

35. The instantaneous centres which vary with the configuration of mechanism are called
A. Permanent instantaneous centres
B. Fixed instantaneous centres
C. Neither fixed nor permanent instantaneous centres
D. None of the above
Answer : C

36. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
A. Static friction
B. Dynamic friction
C. Limiting friction
D. Coefficient of friction
Answer : C

37. In a Hartnell governor, the compression of the spring is __________ the lift of the sleeve.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

38. 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

39. A point on a link connecting double slider crank chain traces a
A. Ellipse
B. Circle
C. Parabola
D. Hyperbola
Answer : A

40. The Hooke's joint consists of:
A. Two forks
B. One fork
C. Three forks
D. Four forks
Answer : A

41. The relative velocity of B with respect to A in a rigid link AB is
A. Parallel to AB
B. Perpendicular to AB
C. Along AB
D. At 45° to AB
Answer : B

42. The maximum fluctuation of speed is the
A. Difference of minimum fluctuation of speed and the mean speed
B. Difference of the maximum and minimum speeds
C. Sum of maximum and minimum speeds
D. Variations of speed above and below the mean resisting torque line
Answer : B

43. The ratio of the number of teeth to the pitch circle diameter in millimetres, is called
A. Circular pitch
B. Diametral pitch
C. Module
D. None of these
Answer : B

44. The type of coupling used to join two shafts whose axes are neither in same straight line nor parallel, but intersect is
A. Flexible coupling
B. Universal coupling
C. Chain coupling
D. Oldham's coupling
Answer : B

45. 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

46. According to Kennedy's theorem, if three bodies have plane motions, their instantaneous centers lie on
A. A triangle
B. A point
C. Two lines
D. A straight line
Answer : D

47. In a drag link quick return mechanism, the shortest link is always fixed. The sum of the shortest and longest link is
A. Equal to sum of other two
B. Greater than sum of other two
C. Less than sum of other two
D. There is no such relationship
Answer : C

48. 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

49. The cam follower generally used in aircraft engines is
A. Knife edge follower
B. Flat faced follower
C. Spherical faced follower
D. Roller follower
Answer : D

50. 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