Theory of Machines 1000+ MCQ with answer for LSAT

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

2. The acceleration of a flat-faced follower when it has contact with the flank of a circular arc cam, is given by
A. ?² R cos?
B. ?² (R - r?) cos?
C. ?² (R - r?) sin?
D. ?² r? sin?
Answer : B

3. If ?/?_n is very high for a body vibrating under steady state vibrations, the phase angle for all values of damping factors, will tend to approach
A. 0°
B. 90°
C. 180°
D. 360°
Answer : C

4. Ball and a Socket forms a
A. Turning pair
B. Rolling pair
C. Screw pair
D. Spherical pair
Answer : D

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. 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

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

8. 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

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. For an involute gear, the ratio of base circle radius and pitch circle radius is equal to
A. sin?
B. cos?
C. sec?
D. cosec?
Answer : B

11. In gears, interference takes place when
A. The tip of a tooth of a mating gear digs into the portion between base and root circles
B. Gears do not move smoothly in the absence of lubrication
C. Pitch of the gears is not same
D. Gear teeth are undercut
Answer : A

12. A mechanism is an assemblage of
A. Two links
B. Three links
C. Four or more than four links
D. All of these
Answer : C

13. 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

14. In a differential band brake as shown in the below figure, if the length OB is greater than OA, then the force P at C should act in the downward direction.
A. Yes
B. No
C. Unpredictable
D. None of these
Answer : B

15. 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

16. Hart mechanism has
A. Eight links
B. Six links
C. Four links
D. Twelve links
Answer : B

17. 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

18. In a multiple V-belt drive, if one of the belts is broken, then we should replace
A. The broken belt only
B. All the belts
C. The broken belt and the belts on either side of it
D. None of the above
Answer : B

19. There are six gears A, B, C, D, E and F in a compound train. The numbers of teeth in the gears are 20, 60, 30, 80, 25 and 75 respectively. The ratio of angular speeds of the driven (F) to the driver (A) of the drive is
A. 1/24
B. 1/8
C. 4/15
D. 12
Answer : A

20. In gramophones for adjusting the speed of the turntable, the following type of governor is commonly employed
A. Hartung governor
B. Wilson Hartnell governor
C. Pickering governor
D. Inertia governor
Answer : C

21. Kinematic pairs are those which have
A. Two elements held together mechanically
B. Two elements having relative motion
C. Two elements having Coriolis component
D. Minimum of two instantaneous centres
Answer : B

22. 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

23. The velocity of any point in mechanism relative to any other point on the mechanism on velocity polygon is represented by the line
A. Joining the corresponding points
B. Perpendicular to line as per (A)
C. Not possible to determine with these data
D. At 45° to line as per (A)
Answer : A

24. 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

25. 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

26. Peaucelliers mechanism has
A. Eight links
B. Six links
C. Four links
D. Twelve links
Answer : A

27. The primary 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 : B

28. A thin circular disc is rolling with a uniform linear speed, along a straight path on a plane surface. Which of the following statement is correct in this regard?
A. All points of the disc have the same velocity
B. The centre of the disc has zero acceleration
C. The centre of the disc has centrifugal acceleration
D. The point on the disc making contact with the plane surface has zero acceleration
Answer : B

29. 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

30. 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

31. In a steam engine, the earlier cut-off with a simple slide valve may be obtained by increasing the steam lap and the angle of advance of the eccentric but keeping constant the travel and lead of the valve, this method will
A. Cause withdrawing or throttling of steam
B. Reduce length of effective stroke of piston
C. Reduce maximum opening of port to steam
D. All of these
Answer : C

32. 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

33. If the damping factor for a vibrating system is unity, then the system will be
A. Over damped
B. Under damped
C. Critically damped
D. Without vibrations
Answer : C

34. In a four bar chain or quadric cycle chain
A. Each of the four pairs is a turning pair
B. One is a turning pair and three are sliding pairs
C. Two are turning pairs and two are sliding pairs
D. Three are turning pairs and one is a sliding pair
Answer : A

35. The lower pair is a
A. Open pair
B. Closed pair
C. Sliding pair
D. Point contact pair
Answer : B

36. Which of the following statements regarding laws governing the friction between dry surfaces are correct?
A. The friction force is dependent on the materials of the contact surfaces.
B. The friction force is directly proportional to the normal force.
C. The friction force is independent of me area of contact.
D. All of the above
Answer : D

37. 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

38. A circle passing through the pitch point with its center at the center of cam axis is known as
A. Pitch circle
B. Base circle
C. Prime circle
D. Outer circle
Answer : C

39. The essential condition of placing the two masses, so that the system becomes dynamically equivalent, is (where l? and l? = Distance of two masses from the centre of gravity of the body, and kG = Radius of gyration of the body)
A. l? = k_G
B. l? = k_G
C. l?l? = k_G
D. l?l? = k_G²
Answer : D

40. The component of the acceleration, perpendicular to the velocity of the particle, at the given instant is called
A. Radial component
B. Tangential component
C. Coriolis component
D. None of these
Answer : A

41. Transmission of power from the engine to the rear axle of an automobile is by means of
A. Compound gears
B. Worm and wheel method
C. Hooke's joint
D. Crown gear
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. The size of a gear is usually specified by
A. Pressure angle
B. Circular pitch
C. Diametral pitch
D. Pitch circle diameter
Answer : D

44. The frictional torque transmitted in a flat collar bearing, considering uniform wear, 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 : A

45. 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

46. A Hartnell governor has its controlling force (Fc) given by Fc = ar + b, where r is the radius of rotation and a and b are constants. The governor becomes isochronous when
A. a is +ve and b = 0
B. a = 0 and b is +ve
C. a is +ve and b is -ve
D. a is +ve and b is also +ve
Answer : A

47. 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

48. 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

49. A body is said to be under forced vibrations, when
A. There is a reduction in amplitude after every cycle of vibration
B. No external force acts on a body, after giving it an initial displacement
C. A body vibrates under the influence of external force
D. None of the above
Answer : A

50. 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