1000+ Theory of Machines MCQ for ISRO Recruitment [Solved]

1. 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

2. 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

3. 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

4. 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

5. Which of the following has sliding motion?
A. Crank
B. Connecting rod
C. Crank pin
D. Crosshead
Answer : D

6. Flexible coupling is used because
A. It is easy to disassemble
B. It is easy to engage and disengage
C. It transmits shocks gradually
D. It prevents shock transmission and eliminates stress reversals
Answer : D

7. The primary unbalanced force is maximum _________ in one revolution of the crank.
A. Twice
B. Four times
C. Eight times
D. Sixteen times
Answer : A

8. In a radial cam, the follower moves
A. In a direction perpendicular to the cam axis
B. In a direction parallel to the cam axis
C. In any direction irrespective of the cam axis
D. Along the cam axis
Answer : A

9. For low and moderate speed engines, the cam follower should move with
A. Uniform velocity
B. Simple harmonic motion
C. Uniform acceleration and retardation
D. Cycloidal motion
Answer : B

10. 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

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

12. 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

13. If some links are connected such that motion between them can take place in more than one direction, it is called
A. Incompletely constrained motion
B. Partially constrained motion
C. Completely constrained motion
D. Successfully constrained motion
Answer : A

14. 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

15. The contact ratio for gears is
A. Zero
B. Less than one
C. Greater than one
D. Infinity
Answer : C

16. 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

17. A shaft carrying two rotors at its ends will have
A. No node
B. One node
C. Two nodes
D. Three nodes
Answer : B

18. When two pulleys are connected by means of a cross belt drive, then both the pulleys will rotate in __________ directions.
A. Same
B. Opposite
C. Perpendicular
D. None of these
Answer : B

19. Crowning on pulleys helps
A. In increasing velocity ratio
B. In decreasing the slip of the belt
C. For automatic adjustment of belt position so that belt runs centrally
D. Increase belt and pulley life
Answer : C

20. A single degree of freedom system is given by, m × (d²x/dt²) + c × (dx/dt) + sx = F.cos?.t with usual notations. It represents
A. Free vibration with damping
B. Free vibration without damping
C. Forced vibration with damping
D. Forced vibration without damping
Answer : C

21. The factional torque for square thread at the mean radius r while raising load W is given by
A. T = W.r tan(? - ?)
B. T = W.r tan(? + ?)
C. T = W.r tan?
D. T = W.r tan?
Answer : B

22. Bifilar suspension method is used to find the
A. Angular acceleration of the body
B. Moment of inertia of the body
C. Periodic time of the body
D. Frequency of vibration of the body
Answer : B

23. Which of the following is a turning 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 : B

24. In a locomotive, the maximum magnitude of the unbalanced force along the perpendicular to the line of stroke, is known as
A. Tractive force
B. Swaying couple
C. Hammer blow
D. None of these
Answer : C

25. 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

26. A point on a connecting link (excluding end points) of a double slider crank mechanism traces a
A. Straight line path
B. Hyperbolic path
C. Parabolic path
D. Elliptical path
Answer : D

27. A Hartnell governor is a
A. Dead weight governor
B. Pendulum type governor
C. Spring loaded governor
D. Inertia governor
Answer : C

28. 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

29. Which of the following is a pendulum type governor?
A. Watt governor
B. Porter governor
C. Hartnell governor
D. None of these
Answer : A

30. 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

31. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is ?. The effort applied parallel to the plane is given by (where ? = tan ? = Coefficient of friction between the plane and the body)
A. P = W tan ?
B. P = W tan (? + ?)
C. P = W (sin ? + ? cos ?)
D. P = W (cos ? + ? sin ?)
Answer : C

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

33. 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

34. A governor is said to be stable, if the
A. Radius of rotation of balls increases as the equilibrium speed decreases
B. Radius of rotation of balls decreases as the equilibrium speed decreases
C. Radius of rotation of balls increases as the equilibrium speed increases
D. Radius of rotation of balls decreases as the equilibrium speed increases
Answer : C

35. 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

36. 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

37. In S.H.M., the velocity vector w.r.t. displacement vector
A. Leads by 90°
B. Lags by 90°
C. Leads by 180°
D. Are in phase
Answer : A

38. 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

39. Rectilinear motion of piston is converted into rotary by
A. Cross head
B. Slider crank
C. Connecting rod
D. Gudgeon pin
Answer : B

40. In railway axle boxes, the bearing used is
A. Deep groove ball bearing
B. Double row self aligning ball bearing
C. Double row spherical roller bearing
D. Cylindrical roller bearing
Answer : C

41. The relation between number of pairs (p) forming a kinematic chain and the number of links (l) is
A. l = 2p - 2
B. l = 2p - 3
C. l = 2p - 4
D. l = 2p - 5
Answer : C

42. 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

43. The pair is known as a higher pair, when the relative motion between the elements of a pair is
A. Turning only
B. Sliding only
C. Rolling only
D. Partly turning and partly sliding
Answer : D

44. A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is
A. 5,367 r.p.m.
B. 6,000 r.p.m.
C. 9,360 r.p.m.
D. 12,000 r.p.m.
Answer : A

45. A machine mounted on a single coil spring has a period of free vibration of tp . If the spring is cut into four equal parts and placed in parallel and the machine is mounted on them, then the period of free vibration of the new system will become
A. t_p /16
B. t_p /4
C. 4 t_p
D. 16 t_p
Answer : B

46. 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

47. Any point on a link connecting double slider crank chain will trace a
A. Straight line
B. Circle
C. Ellipse
D. Parabola
Answer : C

48. When the axes of the first and last wheels are coaxial, then the train is known as
A. Simple train of wheels
B. Compound train of wheels
C. Reverted gear train
D. Epicyclic gear train
Answer : C

49. 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

50. 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