1000+ Theory of Machines MCQ for XAT [Solved]

1. The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
A. 12
B. 14
C. 18
D. 24
Answer : C

2. The tractive force is maximum or minimum when the angle of inclination of crank with the line of stroke (?) is equal to
A. 0° and 90°
B. 90° and 180°
C. 135° and 315°
D. 270° and 360°
Answer : B

3. In a cone pulley, if the sum of radii of the pulleys on the driving and driven shafts is Constant, then
A. Open belt drive is recommended
B. Crossed belt drive is recommended
C. Both open belt drive and crossed belt drive is recommended
D. The drive is recommended depending upon the torque transmitted
Answer : B

4. 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

5. The maximum fluctuation of energy is the
A. Difference between the maximum and minimum energies
B. Sum of the maximum and minimum energies
C. Variations of energy above and below the mean resisting torque line
D. Ratio of the mean resisting torque to the workdone per cycle
Answer : A

6. A spring controlled governor is said to be stable if the controlling force line when produced intersects the Y-axis
A. At the origin
B. Below the origin
C. Above the origin
D. Any one of these
Answer : B

7. Power 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 : D

8. The coriolis component of acceleration exists whenever a point moves along a path that has
A. Linear displacement
B. Rotational motion
C. Gravitational acceleration
D. Tangential acceleration
Answer : B

9. The secondary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, ? = Angular speed of crank, r = Radius of crank, ? = Angle of inclination of crank with the line of stroke, and n = Ratio of the length of connecting rod to radius of crank)
A. m.?².r sin?
B. m.?².r cos?
C. m.?².r (sin 2?/n)
D. m.?².r (cos 2?/n)
Answer : D

10. Relationship between the number of links (L) and number of pairs (P) is
A. P = 2L - 4
B. P = 2L + 4
C. P = 2L + 2
D. P = 2L - 2
Answer : C

11. In a steam engine, the link constitutes a
A. Piston, piston rod and crosshead
B. Connecting rod with big and small end brasses, caps and bolts
C. Crank pin, crankshaft and flywheel
D. All of the above
Answer : D

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

13. 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

14. The minimum periodic time of a compound pendulum is
A. (1/2?). ?(k_G/g)
B. (1/2?). ?(2k_G/g)
C. 2?. ?(k_G/g)
D. 2?. ?(2k_G/g)
Answer : D

15. The amplitude of vibration is always __________ the radius of the circle.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

16. Oldhams coupling is an inversion of the kinematic chain used in
A. Whitworth quick return mechanism
B. Elliptical trammels
C. Rotary engine
D. Universal joint
Answer : B

17. When the belt is stationary, it is subjected to some tension known as initial tension. The value of this tension is equal to the
A. Tension in the tight side of the belt
B. Tension in the slack side of the belt
C. Sum of the tensions on the tight side and slack side of the belt
D. Average tension of the tight side and slack side of the belt
Answer : D

18. The steering of a ship means
A. Movement of a complete ship up and down in vertical plane about transverse axis
B. Turning of a complete ship in a curve towards right or left, while it moves forward
C. Rolling of a complete ship sideways
D. None of the above
Answer : B

19. 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

20. Pulley in a belt drive acts as
A. Cylindrical pair
B. Turning pair
C. Rolling pair
D. Sliding pair
Answer :

21. For dynamic balancing of a shaft
A. The net dynamic force acting on the shaft is equal to zero
B. The net couple due to the dynamic forces acting on the shaft is equal to zero
C. Both (A) and (B)
D. None of the above
Answer : C

22. The ratio of the driving tensions for V-belts is __________ times that of flat belts. (Where ? = Semi-angle of the groove)
A. sin?
B. cos?
C. cosec?
D. sec?
Answer : C

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

24. A simple spring-mass vibrating system has a natural frequency of fn. If the spring stiffness is halved and the mass is doubled, then the natural frequency will become
A. f_n/2
B. 2 f_n
C. 4 f_n
D. 8 f_n
Answer : A

25. The transmissibility, for all values of damping factor, will be less than unity, if ?/?_n is
A. Equal to 1
B. Less than 2
C. Equal to 2
D. Greater than 2
Answer : D

26. Which of the following mechanism is an approximate straight line motion mechanism?
A. Watt's mechanism
B. Grasshopper mechanism
C. Robert's mechanism
D. All of these
Answer : D

27. The size of cam depends upon
A. Base circle
B. Pitch circle
C. Prime circle
D. Pitch curve
Answer : A

28. The acceleration of the particle moving with simple harmonic motion is _________ at the mean position.
A. Zero
B. Minimum
C. Maximum
D. None of these
Answer : A

29. 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

30. Klein's construction is useful to determine
A. Velocity of various parts
B. Acceleration of various parts
C. Displacement of various parts
D. Angular acceleration of various parts
Answer : B

31. 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

32. A kinematic chain is known as a mechanism when
A. None of the links is fixed
B. One of the links is fixed
C. Two of the links are fixed
D. None of these
Answer : B

33. 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

34. The equation of motion for a vibrating system with viscous damping is (d²x/dt²) + (c/m).(dx/dt) + (s/m).x = 0, if the roots of the equation are __________ then the system will be under damped.
A. Equal
B. Real
C. Complex conjugate
D. None of these
Answer : C

35. 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

36. 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

37. 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

38. In automobiles the power is transmitted from gear box to differential through
A. Bevel gear
B. Universal joint
C. Hooke's joint
D. Knuckle joint
Answer : C

39. For the brake to be self locking, the force P at C shown in the below figure, should
A. Be zero
B. Act in upward direction
C. Act in downward direction
D. None of these
Answer : A

40. 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

41. 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

42. Which of the following is an open pair?
A. Ball and socket joint
B. Journal bearing
C. Lead screw and nut
D. Cam and follower
Answer : A

43. 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

44. Which of the following is a spring controlled governor?
A. Hartnell governor
B. Hartung governor
C. Wilson-Hartnell governor
D. All of these
Answer : D

45. 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

46. The frictional torque transmitted in a conical pivot bearing, considering uniform wear, is
A. (1/2) ? W R cosec ?
B. (2/3) ? W R cosec ?
C. (3/4) ? W R cosec ?
D. ? W R cosec ?
Answer : A

47. The Klein's diagram is useful to find
A. Displacement of various parts
B. Velocity of various parts
C. Acceleration of various parts
D. Angular acceleration of various parts
Answer : C

48. Which of the following statement is correct?
A. The primary unbalanced force is less than the secondary unbalanced force.
B. The primary unbalanced force is maximum twice in one revolution of the crank.
C. The unbalanced force due to reciprocating masses varies in magnitude and direction both.
D. The magnitude of swaying couple in locomotives is inversely proportional to the distance between the two cylinder centre lines
Answer : B

49. In a pantograph, all the pairs are
A. Turning pairs
B. Sliding pairs
C. Spherical pairs
D. Self-closed pairs
Answer : A

50. 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