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

1. 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 this equation are real, then the system will be
A. Over-damped
B. Under damped
C. Critically damped
D. Without vibrations
Answer : A

2. When a point moves along a straight line, its acceleration will have
A. Radial component only
B. Tangential component only
C. Coriolis component only
D. Radial and tangential components both
Answer : B

3. 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

4. Pitch point of a cam is
A. A point on the pitch curve having minimum pressure angle
B. A point on the pitch curve having maximum pressure angle
C. Any point on the pitch curve
D. Any point on the pitch circle
Answer : B

5. 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

6. The radial distance from the top of a tooth to the bottom of a tooth in a meshing gear, is called
A. Dedendum
B. Addendum
C. Clearance
D. Working depth
Answer : C

7. The critical speed of a shaft in revolution per second is __________ as that of natural frequency of transverse vibration.
A. Same
B. Different
C. Unpredictable
D. None of these
Answer : A

8. The static friction
A. Bears a constant ratio to the normal reaction between the two surfaces
B. Is independent of the area of contact, between the two surfaces
C. Always acts in a direction, opposite to that in which the body tends to move
D. All of the above
Answer : D

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

10. Which of the following is a higher pair?
A. Turning pair
B. Screw pair
C. Belt and pulley
D. None of the above
Answer : C

11. 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

12. For simple harmonic motion of the of follower, a cosine curve represents
A. Displacement diagram
B. Velocity diagram
C. Acceleration diagram
D. All of the above
Answer : C

13. Two systems shall be dynamically equivalent when
A. The mass of two are same
B. C.G. of two coincides
C. M.I. of two about an axis through e.g. is equal
D. All of the above
Answer : D

14. 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

15. 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

16. The ratio of height of Porter governor (when length of arms and links are equal) to the height of Watt's governor is (where m = Mass of the ball, and M = Mass on the sleeve)
A. m/(m + M)
B. M/(m + M)
C. (m + M)/m
D. (m + M)/M
Answer : C

17. 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

18. 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

19. 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

20. 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

21. The Ackermann steering mechanism is preferred to the Davis type in automobiles because
A. The former is mathematically accurate
B. The former is having turning pair
C. The former is most economical
D. The former is most rigid
Answer : B

22. It is required to connect two parallel shafts, the distance between whose axes is small and variable. The shafts are coupled by
A. Universal joint
B. Knuckle joint
C. Oldham's coupling
D. Flexible coupling
Answer : C

23. The number of centers in a crank driven slider crank mechanism is
A. 0
B. 2
C. 4
D. 6
Answer : B

24. Which of the following disciplines provides study of relative motion between the parts of a machine?
A. Theory of machines
B. Applied mechanics
C. Mechanisms
D. Kinematics
Answer : D

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

26. 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

27. 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

28. The efficiency of a screw jack is maximum, when (where ? = Helix angle, and ? = Angle of friction)
A. ? = 45° + ?/2
B. ? = 45° - ?/2
C. ? = 90° + ?
D. ? = 90° - ?
Answer : B

29. When there is a reduction in amplitude over every cycle of vibration, then the body is said to have
A. Free vibration
B. Forced vibration
C. Damped vibration
D. Under damped vibration
Answer : C

30. 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

31. In a rigid link OA, velocity of A w.r.t. O will be
A. Parallel to OA
B. Perpendicular to OA
C. At 45° to OA
D. Along AO
Answer : B

32. The swaying couple is due to the
A. Primary unbalanced force
B. Secondary unbalanced force
C. Two cylinders of locomotive
D. Partial balancing
Answer : A

33. Efficiency of a screw jack is given by
A. tan (? + ?)/tan?
B. tan?/tan (? +?)
C. tan (? - ?)/tan?
D. tan?/tan (? - ?)
Answer : B

34. 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

35. 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

36. The partial balancing means
A. Balancing partially revolving masses
B. Balancing partially reciprocating masses
C. Best balancing of engines
D. All of these
Answer : B

37. 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

38. The inversion of a mechanism is
A. Changing of a higher pair to a lower pair
B. Turning its upside down
C. Obtained by fixing different links in a kinematic chain
D. Obtained by reversing the input and output motion
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. 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

41. The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as
A. Damping factor
B. Damping coefficient
C. Logarithmic decrement
D. Magnification factor
Answer : D

42. The working depth of a gear is the radial distance from the
A. Pitch circle to the bottom of a tooth
B. Pitch circle to the top of a tooth
C. Top of a tooth to the bottom of a tooth
D. Addendum circle to the clearance circle
Answer : D