Theory of Machines MCQ Solved Paper for SSC CPO

1. The velocity of the belt for maximum power is (where m = Mass of the belt in kg per metre length)
A. T/3
B. (T.g)/3
C. ?(T/3m)
D. ?(3m/T)
Answer : C

2. Maximum fluctuation of energy in a flywheel is equal to [where I = Mass moment of inertia of the flywheel, E = Maximum fluctuation of energy, CS = Coefficient of fluctuation of speed, and ? = Mean angular speed = (?? + ??)/2]
A. I.?.(?? - ??)
B. I.?².C_S
C. 2.E.C_S
D. All of these
Answer : D

3. Creep in belt drive is due to
A. Weak material of the belt
B. Weak material of the pulley
C. Uneven extensions and contractions of the belt when it passes from tight side to slack side
D. Expansion of the belt
Answer : C

4. 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

5. Klein's construction gives a graphic construction for
A. Slider-crank mechanism
B. Velocity polygon
C. Acceleration polygon
D. Four bar chain mechanism
Answer : C

6. The contact ratio is given by
A. (Length of the path of approach)/(Circular pitch)
B. (Length of path of recess)/(Circular pitch)
C. (Length of the arc of contact)/(Circular pitch)
D. (Length of the arc of approach)/cos?
Answer : C

7. In a simple harmonic motion, the velocity vector with respect to displacement vector
A. Is in phase
B. Leads by 90°
C. Leads by 180°
D. Lags by 90°
Answer : D

8. The two parallel and coplanar shafts are connected by gears having teeth parallel to the axis of the shaft. This arrangement is known as
A. Spur gearing
B. Helical gearing
C. Bevel gearing
D. Spiral gearing
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. A typewriter mechanism has 7 numbers of binary joints, six links and none of higher pairs. The mechanism is
A. Kinematically sound
B. Not sound
C. Soundness would depend upon which link is kept fixed
D. Data is not sufficient to determine same
Answer : A

11. The velocity of sliding __________ the distance of the point of contact from the pitch point.
A. Is directly proportional to
B. Is inversely proportional to
C. Is equal to cos ? multiplied by
D. Does not depend upon
Answer : A

12. Module of a gear is
A. D/T
B. T/D
C. 2D/T
D. 2T/D
Answer : A

13. A body in motion will be subjected to coriolis acceleration when that body is
A. In plane rotation with variable velocity
B. In plane translation with variable velocity
C. In plane motion which is a resultant of plane translation and rotation
D. Restrained to rotate while sliding over another body
Answer : D

14. 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

15. 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

16. The number of links and instantaneous centers in a reciprocating engine mechanism are
A. 4, 4
B. 4, 5
C. 5, 4
D. 4, 6
Answer : D

17. The static balancing is satisfactory for low speed rotors but with increasing speeds, dynamic balancing becomes necessary. This is because, the
A. Unbalanced couples are caused only at higher speeds
B. Unbalanced forces are not dangerous at higher speeds
C. Effects of unbalances are proportional to the square of the speed
D. Effects of unbalances are directly proportional to the speed
Answer : C

18. When one of the links of a kinematic chain is fixed, the chain is known as a
A. Structure
B. Mechanism
C. Inversion
D. Machine
Answer : B

19. Which of the following is a higher pair?
A. Belt and pulley
B. Turning pair
C. Screw pair
D. Sliding pair
Answer : A

20. 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

21. The maximum efficiency of spiral gears is (where ? = Shaft angle, and ? = Friction angle)
A. sin (? + ?) + 1/ cos (? - ?) + 1
B. cos (? - ?) + 1/ sin (? + ?) + 1
C. cos (? + ?) + 1/ cos (? - ?) + 1
D. cos (? - ?) + 1/ cos (? + ?) + 1
Answer : C

22. When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
A. Minimum
B. Zero
C. Maximum
D. None of these
Answer : B

23. Which of the following statement is wrong?
A. A round bar in a round hole form a turning pair
B. A square bar in a square hole form a sliding pair
C. A vertical shaft in a foot step bearing forms a successful constraint
D. All of the above
Answer : C

24. 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

25. 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

26. An imaginary circle which by pure rolling action, gives the same motion as the actual gear, is called
A. Addendum circle
B. Dedendum circle
C. Pitch circle
D. Clearance circle
Answer : C

27. In order to double the period of a simple pendulum, the length of the string should be
A. Halved
B. Doubled
C. Quadrupled
D. None of these
Answer : C

28. In a flat collar pivot bearing, the moment due to friction is proportional to
A. (r?² - r?²)/(r? - r?)
B. (r?² - r?²)/(r? + r?)
C. (r?³ - r?³)/(r?² - r?²)
D. (r?³ - r?³)/(r? - r?)
Answer : C

29. An automobile steering gear is an example of
A. Sliding pair
B. Rolling pair
C. Lower pair
D. Higher pair
Answer : C

30. In a Hartnell governor, if a spring of greater stiffness is used, then the governor will be
A. Less sensitive
B. More sensitive
C. Unaffected of sensitivity
D. Isochronous
Answer : A

31. If there are L number of links in a mechanism, then number of possible inversions is equal to
A. L + 1
B. L - 1
C. L
D. L + 2
Answer : C

32. In a locomotive, the resultant unbalanced force due to the two cylinders along the line of stroke, is known as
A. Tractive force
B. Swaying couple
C. Hammer blow
D. None of these
Answer : A

33. One end of a helical spring is fixed while the other end carries the load W which moves with simple harmonic motion. The frequency of motion is given by (where ? = Deflection of the spring)
A. 2?. ?(g/?)
B. 1/2?. ?(g/?)
C. 2?. ?(?/g)
D. 1/2?. ?(?/g)
Answer : B

34. 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

35. Torsional vibrations are said to occur when the particles of a body moves
A. Perpendicular to its axis
B. Parallel to its axis
C. In a circle about its axis
D. None of these
Answer : C

36. 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

37. A mechanism __________ for transmitting or transforming motion.
A. Can be used
B. Cannot be used
C. Unpredictable
D. None of these
Answer : A

38. A disturbing mass m? attached to the rotating shaft may be balanced by a single mass m? attached in the same plane of rotation as that of m?, such that (where r? and r? are the radii of rotation of m? and m? respectively)
A. m?r? = m?r?
B. m?r? = m?r?
C. m?m? = r?r?
D. None of these
Answer : B

39. When a ship travels in a sea, which of the effect is more dangerous
A. Steering
B. Pitching
C. Rolling
D. All of the above
Answer : B

40. Rectangular bar in a rectangular hole is the following type of pair
A. Completely constrained motion
B. Partially constrained motion
C. Incompletely constrained motion
D. Freely constrained motion
Answer : A

41. The maximum velocity of a particle moving with simple harmonic motion is
A. ?
B. ?r
C. ?²r
D. ?/r
Answer : B

42. Which of the following is false statement in respect of differences between machine and structure?
A. Machines transmit mechanical work, whereas structures transmit forces
B. In machines, relative motion exists between its members, whereas same does not exist in case of structures
C. Machines modify movement and work, whereas structures modify forces
D. Efficiency of machines as well as structures is below 100%
Answer : D

43. The coriolis component of acceleration depends upon
A. Velocity of slider
B. Angular velocity of the link
C. Both (A) and (B)
D. None of these
Answer : C

44. In its simplest form, a cam mechanism consists of following number of links
A. 1
B. 2
C. 3
D. 4
Answer : C

45. In which of the following type of gear train the first gear and the last gear are co-axial.
A. Simple gear train
B. Compound gear train
C. Reverted gear train
D. None of the above
Answer : C

46. In a spring controlled governor, when the controlling force ________ as the radius of rotation increases, it is said to be a stable governor.
A. Remains constant
B. Decreases
C. Increases
D. None of these
Answer : C

47. A mechanism consisting of four links is called a __________ mechanism.
A. Simple
B. Compound
C. Binary
D. None of these
Answer : A

48. Which of the following is an inversion of a single slider crank chain?
A. Pendulum pump
B. Oscillating cylinder engine
C. Rotary internal combustion engine
D. All of these
Answer : D

49. When the nature of contact between the elements of a pair is such that one element can turn about the other by screw threads, the pair is known as a
A. Screw pair
B. Spherical pair
C. Turning pair
D. Sliding pair
Answer : A

50. The load cup of a screw jack is made separate from the head of the spindle to
A. Enhance the load carrying capacity of the jack
B. Reduce the effort needed for lifting the working load
C. Reduce the value of frictional torque required to be countered for lifting the load
D. Prevent the rotation of load being lifted
Answer : D