1000+ Theory of Machines Multiple Choice Question Answer [Solved]

1. Angle of action of cam is defined as the angle
A. Of rotation of the cam for a definite displacement of the follower
B. Through which the cam rotates during the period in which the follower remains in the highest position
C. Moved by the cam from the instant the follower begins to rise, till it reaches its highest position
D. Moved by the cam from beginning of ascent to the termination of descent
Answer : D

2. When the radius of rotation of balls __________ as the equilibrium speed increases, the governor is said to be unstable.
A. Remains constant
B. Decreases
C. Increases
D. None of these
Answer : B

3. The driving and driven shafts connected by a Hooke's joint will have equal speeds, if
A. cos? = sin?
B. sin? = ± tan?
C. tan? = ± cos?
D. cot? = cos?
Answer : C

4. The purpose of a link is to
A. Transmit motion
B. Guide other links
C. Act as a support
D. All of the above
Answer : D

5. A pantograph is a mechanism with
A. Lower pairs
B. Higher pairs
C. Rolling pairs
D. Turning pairs
Answer : A

6. The flank of the tooth is the surface of the tooth __________ the pitch surface.
A. Above
B. Below
C. At
D. None of these
Answer : B

7. Whitworth quick return mechanism is obtained by inversion of
A. Slider crank mechanism
B. Kinematic chain
C. Five link mechanism
D. Roller cam mechanism
Answer : A

8. The mechanism forms a structure, when the number of degrees of freedom (n) is equal to
A. 0
B. 1
C. 2
D. -1
Answer : A

9. When the load on the engine increases, it becomes necessary to increase the supply of working fluid and when the load decreases, less working fluid is required. The supply of the working fluid to the engine is controlled by a
A. D-slide valve
B. Governor
C. Meyer's expansion valve
D. Flywheel
Answer : B

10. Kinematic 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 : D

11. The frictional torque transmitted in a flat collar bearing, considering uniform pressure, is (where r? and r? = External and internal radii of collar respectively)
A. (1/2). ? W (r? + r?)
B. (2/3). ? W (r? + r?)
C. (1/2). ? W [(r?³ - r?³)/(r?² - r?²)]
D. (2/3). ? W [(r?³ - r?³)/(r?² - r?²)]
Answer : D

12. Longitudinal 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 : B

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

14. In an ideal machine, the output as compared to input is
A. Less
B. More
C. Equal
D. May be less or more depending on efficiency
Answer : C

15. The following is the inversion of slider crank chain mechanism
A. Whitworth quick return mechanism
B. Hand pump
C. Oscillating cylinder engine
D. All of the above
Answer : D

16. Which of the following is an inversion of a double slider crank chain?
A. Oldham's coupling
B. Elliptical trammel
C. Scotch yoke mechanism
D. All of these
Answer : D

17. When a body moves with simple harmonic motion, the product of its periodic time and frequency is equal to
A. Zero
B. One
C. ?/2
D. ?
Answer : B

18. With single Hooke's joint it is possible to connect two shafts, the axes of which have an angular misalignment up to
A. 10°
B. 20°
C. 30°
D. 40°
Answer : D

19. The secondary unbalanced force is maximum __________ in one revolution of the crank.
A. Two times
B. Four times
C. Eight times
D. Sixteen times
Answer : B

20. The Kutzbach criterion for determining the number of degrees of freedom (n) is (where l = number of links, j = number of joints and h = number of higher pairs)
A. n = 3(l - 1) - 2j - h
B. n = 2(l - 1) -2j - h
C. n = 3(l - 1) - 3j - h
D. n = 2(l - 1) - 3j - h
Answer : A

21. The velocity of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by (where ? = Angular velocity of the cam shaft)
A. ? (r? r?) sin?
B. ? (r? + r?) sin? sec2?
C. ? (r? r?) cos?
D. ? (r? + r?) cos? cosec2?
Answer : B

22. 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

23. In a four-bar chain it is required to give an oscillatory motion to the follower for a continuous rotation of the crank. For the lengths of 50 mm of crank and 70 mm of the follower, determine theoretical maximum length of coupler. The minimum length of the coupler will be
A. 45 mm
B. Slightly less than 45 mm
C. Slightly more than 45 mm
D. 95 mm
Answer : C

24. Which of the following property of the instantaneous centre is correct?
A. A rigid link rotates instantaneously relative to another link at the instantaneous centre for the configuration of the mechanism considered.
B. The two rigid links have no linear velocity relative to each other at the instantaneous centre.
C. The velocity of the instantaneous centre relative to any third rigid link is same whether the instantaneous centre is regarded as a point on the first rigid link or on the second rigid link.
D. All of the above
Answer : D

25. The main disadvantage of the sliding pair is that it is
A. Bulky
B. Wears rapidly
C. Difficult to manufacture
D. Both (A) and (B) above
Answer : D

26. 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

27. 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

28. 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

29. 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

30. 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

31. The equation of free vibrations of a system is (d²x/dt²) +36 ?²x, its natural frequency is
A. 3 Hz
B. 3? Hz
C. 6 Hz
D. 6? Hz
Answer : A

32. A completely constrained motion can be transmitted with.
A. 1 link with pin joints
B. 2 links with pin joints
C. 3 links with pin joints
D. 4 links with pin joints
Answer : D

33. 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

34. Which one of the following can completely balance several masses revolving in different planes on a shaft?
A. A single mass in different planes
B. Two masses in any two planes
C. A single mass in one of the planes of the revolving masses
D. Two equal masses in any two planes
Answer : B

35. The natural frequency of free transverse vibrations due to uniformly distributed load acting over a simply supported shaft is (where ?S = Static deflection of simply supported shaft due to uniformly distributed load)
A. 0.4985/ ??S
B. 0.5615/ ??S
C. 0.571/ ??S
D. 0.6253/ ??S
Answer : B

36. When the addenda on pinion and wheel is such that the path of approach and path of recess are half of their maximum possible values, then the length of the path of contact is given by (where r = Pitch circle radius of pinion, R = Pitch circle radius of wheel, and ? = Pressure angle)
A. [(r² + R²) cos?]/2
B. [(r² + R²) sin?]/2
C. [(r + R) cos?]/2
D. [(r + R) sin?]/2
Answer : D

37. The frequency of damped vibrations with viscous damping is ________ the frequency of undamped vibrations.
A. More than
B. Less than
C. Same as
D. None of these
Answer : B

38. The Bifilar suspension method is used to determine
A. Natural frequency of vibration
B. Position of balancing weights
C. Moment of inertia
D. Centripetal acceleration
Answer : C

39. Two pulleys of radii r? and r? and at distance x apart are connected by means of an open belt drive. The length of the belt is
A. ? (r? + r?) + (r? + r?)²/x + 2x
B. ? (r? + r?) + (r? - r?)²/x + 2x
C. ? (r? - r?) + (r? - r?)²/x + 2x
D. ? (r? - r?) + (r? + r?)²/x + 2x
Answer : B

40. 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 throghout the teeth engagement.
Answer : D

41. The height of a Watt's governor (in metres) is equal to (where N = Speed of the arm and ball about the spindle axis)
A. 8.95/N²
B. 89.5/N²
C. 895/N²
D. 8950/N²
Answer : C

42. A watt's governor can work satisfactorily at speeds from
A. 60 to 80 r.p.m.
B. 80 to 100 r.p.m.
C. 100 to 200 r.p.m.
D. 200 to 300 r.p.m.
Answer : A

43. An exact straight line motion mechanism is a
A. Scott-Russell's mechanism
B. Hart's mechanism
C. Peaucellier's mechanism
D. All of these
Answer : D

44. The relation l = (2/3).(j + 2) apply only to kinematic chains in which lower pairs are used. This may be used to kinematic chains in which higher pairs are used, but each higher pair may be taken as equivalent to
A. One lower pair and two additional links
B. Two lower pairs and one additional link
C. Two lower pairs and two additional links
D. Any one of these
Answer : B

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

46. Which gear train is used for higher velocity ratios in a small space?
A. Simple gear train
B. Compound gear train
C. Reverted gear train
D. Epicyclic gear train
Answer : D

47. Which of the following is an inversion of Single slider crank chain?
A. Beam engine
B. Rotary engine
C. Oldhams coupling
D. Elliptical trammel
Answer : B

48. 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

49. Which gear is used for connecting two coplanar and intersecting shafts?
A. Spur gear
B. Helical gear
C. Bevel gear
D. None of the above
Answer : C

50. 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