# Theory of machines MCQ Mechanical Engineering

50 Questions 30 Mins

Following are some of the multiple choice questions on the Theory of machines with answers that will help the students in developing their knowledge.

## Theory of machines MCQ

### 1. The unbalanced primary forces in a reciprocating engine are

• Balanced by secondary forces
• Balanced completely
• Balanced partially
• Not balanced

### 2. The partial balancing of reciprocating parts in locomotives produces

• hammer blow
• swaying couple
• variation in tractive force along the line of stroke
• all of the above

• Right
• Wrong

### 4. Crowning on pulleys helps

• In increasing velocity ratio
• In decreasing the slip of the belt
• For automatic adjustment of belt position so that belt runs centrally
• Increase belt and pulley life

### 5. The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in

• Transverse vibrations
• Torsional vibrations
• Longitudinal vibrations
• All of these

• 9/8
• 9/82
• 9/16
• 9/128

### 7. The example of lower pair is

• Shaft revolving in a bearing
• Straight line motion mechanisms
• Automobile steering gear
• All of the above

### 8. 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)

• n = 3(l - 1) - 2j - h
• n = 2(l - 1) - 2j - h
• n = 3(l - 1) - 3j - h
• n = 2(l - 1) - 3j - h

### 9. Which of the following is an example of sliding pair?

• Piston and cylinder of a reciprocating steam engine
• Shaft with collars at both ends fitted into a circular hole
• Lead screw of a lathe with nut
• Ball and a socket joint

### 10. The maximum fluctuation of energy is the

• Difference between the maximum and minimum energies
• Sum of the maximum and minimum energies
• Variations of energy above and below the mean resisting torque line
• Ratio of the mean resisting torque to the work-done per cycle

### 11. A disturbing mass m₁ attached to the rotating shaft may be balanced by a single mass m₂ attached in the same plane of rotation as that of m₁, such that (where r₁ and r₂ are the radii of rotation of m₁ and m₂ respectively)

• m₁ r₂ = m₂ r₁
• m₁ r₁ = m₂ r₂
• m₁ m₂ = r₁ r₂
• None of these

### 12. A chain comprises of 5 links having 5 joints. Is it kinematic chain?

• Yes
• No
• It is a marginal case
• Data are insufficient to determine it

### 13. Efficiency of a screw jack is given by

• tan (α + φ)/tanα
• tanα/tan (α +φ)
• tan (α - φ)/tanα
• tanα/tan (α - φ)

### 14. 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 is +ve and b = 0
• a = 0 and b is +ve
• a is +ve and b is -ve
• a is +ve and b is also +ve

### 15. The direction of Coriolis component of acceleration is the direction

• Of relative velocity vector for the two coincident points rotated by 90° in the direction of the angular velocity of the rotation of the link
• Along the centripetal acceleration
• Along tangential acceleration
• Along perpendicular to angular velocity

### 16. In a kinematic chain, a quaternary joint is equivalent to

• One binary joint
• Two binary joints
• Three binary joints
• Four binary joints

### 17. Which of the following is an open pair?

• Ball and socket joint
• Journal bearing
• Cam and follower

### 18. The motion of a shaft in a circular hole is an example of

• Completely constrained motion
• Incompletely constrained motion
• Successfully constrained motion
• None of these

• Higher pair
• Lower pair
• Rolling pair
• Sliding pair

• 1.4 N-s/m
• 18.52 N-s/m
• 52.92 N-s/m
• 529.2 N-s/m

### 21. The gear train usually employed in clocks is a

• simple gear train
• reverted gear train
• sun and planet gear
• differential gear

### 22. In order to give the primary balance of the reciprocating parts of a multi-cylinder in-line engines,

• the algebraic sum of the primary forces must be equal to zero
• the algebraic sum of the couples about any point in the plane of the primary forces must be equal to zero
• both (a) and (b)
• none of these

• Right
• Wrong

### 24. A circular bar moving in a round hole is an example of

• Incompletely constrained motion
• Partially constrained motion
• Completely constrained motion
• Successfully constrained motion

### 25. The D-slide valve is also known as

• Piston slide valve
• None of these

### 26. Which of the following is a lower pair?

• Ball and socket i
• Piston and cylinder
• Cam and follower
• Both (A) and (B) above

### 27. Critical damping is a function of

• Mass and stiffness
• Mass and damping coefficient
• Mass and natural frequency
• Damping coefficient and natural frequency

### 28. The Coriolis component of acceleration is taken into account for

• Slider crank mechanism
• Four bar chain mechanism
• Quick return motion mechanism
• All of these

• sliding pair
• rolling pair
• lower pair
• higher pair

### 30. In a screw jack, the effort required to lower the load W is given by

• P = W tan(α - φ)
• P = W tan(α + φ)
• P = W tan(φ - α)
• P = W cos(α + φ)

### 31. In order to balance the reciprocating masses,

• primary forces and couples must be balanced
• secondary forces and couples must be balanced
• both (a) and (b)
• none of these

• True
• False

• pitch circle
• base circle
• pitch curve
• prime circle

• Small
• Too small
• Large
• Too large

### 35. Governor is used in automobile to

• Decrease the variation of speed
• Maximize the fuel economy
• Limit the vehicle speed
• Maintain constant engine speed

### 36. In a Hartnell governor, if a spring of greater stiffness is used, then the governor will be

• Less sensitive
• More sensitive
• Unaffected of sensitivity
• Isochronous

### 37. The axis of precession is __________ to the plane in which the axis of spin is going to rotate.

• Parallel
• Perpendicular
• Both A and B
• None of these

### 38. The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke (θ) is equal to

• 90° and 180°
• 45° and 225°
• 180° and 270°
• 270° and 360°

• 2 mm
• 2.22 mm
• 2.50 mm
• 3.0 mm

### 40. The static friction

• bears a constant ratio to the normal reaction between the two surfaces
• is independent of the area of contact, between the two surfaces
• always acts in a direction, opposite to that in which the body tends to move
• all of the above

• True
• False

### 42. Davis steering gear consists of

• Sliding pairs
• Turning pairs
• Rolling pairs
• Higher pairs

### 43. Ackermann steering gear consists of

• Sliding pairs
• Turning pairs
• Rolling pairs
• Higher pairs

### 44. Which of the following mechanism is obtained from lower pair?

• Gyroscope
• Pantograph
• Valve and valve gears
• All of the above

### 45. A friction circle is a circle drawn when a journal rotates in a bearing. Its radius depends upon the coefficient of friction and the

• Magnitude of the forces on journal
• Angular velocity of journal
• Clearance between journal and bearing

### 46. A foot step bearing and rotor of a vertical turbine form examples of

• Incompletely constrained motion
• Partially constrained motion
• Completely constrained motion
• Successfully constrained motion

• Agree
• Disagree

• Right
• Wrong

• more than
• less than
• same as
• All of above

• 1 - 3 m/s
• 3 - 15 m/s
• 15 - 30 m/s
• 30 - 50 m/s