360+ Mechatronics Solved MCQs

1.

Which of the following is incorrect regarding inertia force?

A. imaginary force
B. acts upon a rigid body
C. brings the body to equilibrium
D. same direction as of accelerating force
Answer» D. same direction as of accelerating force
2.

Inertia torque acts in the same direction as the accelerating couple?

A. true
B. false
Answer» B. false
3.

If a force has a line of action at a distance h from the centre of gravity, then the value of h is given by  

A. i. α/f
B. i. α/m.g
C. i/m.k
D. m.k/i
Answer» A. i. α/f
4.

D-Alembert’s principle is used for which of the following?

A. change static problem into a dynamic problem
B. change dynamic problem to static problem
C. to calculate moment of inertia of rigid bodies
D. to calculate angular momentum of a system of masses
Answer» B. change dynamic problem to static problem
5.

2 D ALEMBERT'S PRINCIPLE - DYNAMIC ANALYSIS IN RECIPROCATING ENGINES

A. reversed effective force
B. net force
C. coriolis force
D. resultant force
Answer» A. reversed effective force
6.

A body remains in equilibrium if  

A. inertia force is applied in the same direction to the resultant force
B. inertia force is applied in the direction opposite to the resultant force
C. inertia force is applied in the direction perpendicular to the resultant force
D. inertia force is applied in the direction parallel to the resultant force
Answer» B. inertia force is applied in the direction opposite to the resultant force
7.

Inertia force and the reversed effective force are the same.

A. true
B. false
Answer» A. true
8.

In the following picture the G is the center of gravity, the quantity h is known as the “offset”. I is the moment of inertia and k is the radius of gyration. Offset’s value is given by?

A. i.α/f
B. i.α/m.g
C. i/m.k
D. m.k/i
Answer» A. i.α/f
9.

Considering a four bar chain with each link having linear and angular acceleration, applying D-Alembert’s principle will never result in which of the following member?

A. 2- force member
B. 3- force member
C. 4 – force member
D. non accelerating member
Answer» A. 2- force member
10.

Piston effort acts along the line of stroke.

A. true
B. false
Answer» A. true
11.

In a horizontal engine, reciprocating parts are accelerated when the piston moves from

A. tdc to bdc
B. bdc to tdc
C. midway to tdc
D. bdc to midway
Answer» A. tdc to bdc
12.

In a horizontal engine, reciprocating parts are retarded when the piston moves from

A. tdc to bdc
B. bdc to tdc
C. midway to tdc
D. bdc to midway
Answer» B. bdc to tdc
13.

When the piston is accelerated, the piston effort is given by which of the following the equation?

A. f(l) – f(i)
B. f(l) + f(i)
C. f(l) ± f(i)
D. f(l) – f(i) + r(f)
Answer» B. f(l) + f(i)
14.

In the presence of frictional resistance, the expression for piston effort is  

A. f(l) – f(i)
B. f(l) + f(i)
C. f(l) ± f(i) – r(f)
D. f(l) – f(i) + r(f)
Answer» C. f(l) ± f(i) – r(f)
15.

Crank effort is the product of crank pin radius and  

A. thrust on sides
B. crankpin effort
C. force acting along connecting rod
D. piston effort
Answer» B. crankpin effort
16.

In a horizontal engine, the weight of the reciprocating parts also add/subtract to the piston effort.

A. true
B. false
Answer» B. false
17.

For the given data of an Internal combustion engine : Mass of parts = 180 kg bore = 175 mm, length of stroke = 200 mm, engine speed = 500 r.p.m., length of connecting rod = 400 mm and crank angle = 60° from T.D.C, find the inertia force.

A. 17.56 n
B. 19.2 n
C. 18.53 n
D. 18.00 n
Answer» C. 18.53 n
18.

45 N/mm2. The connecting rod length between centres is 1.2 m and the cylinder bore is 0.5 m. If the engine runs at 250 r.p.m. and if the effect of piston rod diameter is neglected, calculate the net load on piston.

A. 88000 n
B. 90560 n
C. 78036 n
D. 88357 n
Answer» D. 88357 n
19.

Multi cylinder engines are usually placed at an equal inclination to each other.

A. true
B. false
Answer» A. true
20.

For a multicylinder engine, the coefficient of fluctuation of speed would vary with

A. number of cylinders
B. remains unaffected
C. length of connecting rod
D. input temperature
Answer» B. remains unaffected
21.

In the turning moment diagram of a multicylinder engine, the work done during exhaust stroke is by  

A. the gases
B. on the gases
C. piston wall
D. valve
Answer» B. on the gases
22.

For a 4 cylinder engine, when the pressure inside the cylinders exceeds the atmospheric pressure then.

A. work is done by the gases
B. work is done on the gases
C. work is done on the piston wall
D. work is done by the piston wall
Answer» A. work is done by the gases
23.

In a punching press, which of the following quantity is constant?

A. load
B. torque
C. angular velocity
D. angle of rotation
Answer» B. torque
24.

In a punching press, load is 0 at the time of punching.

A. true
B. false
Answer» B. false
25.

The maximum shear force required for punching depends on  

A. sheared area
B. length of the plate
C. speed of the flywheel
D. total load
Answer» A. sheared area
26.

A machine punching 38 mm holes in 32 mm thick plate requires 7 N-m of energy per sq. mm of sheared area, find the maximum shear force required.

A. 26.7 kn
B. 53.4 kn
C. 13.35 kn
D. 106.8 kn
Answer» A. 26.7 kn
27.

The relation between stroke punch s and radius of crank r is  

A. s=r
B. s=2r
C. s=4r
D. s=r/2
Answer» B. s=2r
28.

If the stroke punch is 100mm, find the radius of the crank in mm.

A. 200
B. 100
C. 50
D. 400
Answer» C. 50
29.

Energy during actual punching operation is same as the energy supplied by the motor.

A. true
B. false
Answer» B. false
30.

The balance energy required for punching is supplied by the flywheel by  

A. increase in its kinetic energy
B. decrease in its kinetic energy
C. decrease in its potential energy
D. by variation of mass
Answer» B. decrease in its kinetic energy
31.

When the length of the connecting rod is unknown then the value (θ2 –θ1)/2π is equal to  

A. t/s
B. t/2s
C. t/2r
D. t/r
Answer» B. t/2s
32.

The size of a cam depends upon

A. base circle
B. pitch circle
C. prime circle
D. pitch curve
Answer» A. base circle
33.

The angle between the direction of the follower motion and a normal to the pitch curve is called

A. pitch angle
B. prime angle
C. base angle
D. pressure angle
Answer» D. pressure angle
34.

The cam follower generally used in automobile engines is

A. knife edge follower
B. flat faced follower
C. spherical faced follower
D. roller follower
Answer» C. spherical faced follower
35.

The cam follower extensively used in air- craft engines is

A. knife edge follower
B. flat faced follower
C. spherical faced follower
D. roller follower
Answer» D. roller follower
36.

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. in a direction perpendicular to the cam axis
37.

A radial follower is one

A. that reciprocates in the guides
B. that oscillates
C. in which the follower translates along an axis passing through the cam centre of rotation.
D. none of the mentioned
Answer» A. that reciprocates in the guides
38.

Ofset is provided to a cam follower mechanism to

A. minimise the side thrust
B. accelerate
C. avoid jerk
D. none of the mentioned
Answer» A. minimise the side thrust
39.

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. simple harmonic motion
40.

For high speed engines, the cam follower should move with

A. uniform velocity
B. simple harmonic motion
C. uniform acceleration and retardation
D. cycloidal motion
Answer» D. cycloidal motion
41.

Which of the following displacement diagrams should be chosen for better dynamic performance of a cam-follower mechanism ?

A. simple hormonic motion
B. parabolic motion
C. cycloidal motion
D. none of the mentioned
Answer» C. cycloidal motion
42.

The displacement of a flat faced follower when it has contact with the flank of a circular arc cam, is given by

A. r(1-cosθ)
B. r(1-sinθ)
C. (r-r1)(1-cosθ)
D. (r-r1)(1-sinθ)
Answer» C. (r-r1)(1-cosθ)
43.

The retardation of a flat faced follower when it has contact at the apex of the nose of a circular arc cam, is given by

A. ω2×oq
B. ω2×oqsinθ
C. ω2×oqcosθ
D. ω2×oqtanθ
Answer» A. ω2×oq
44.

Centre of masses of the system lies on the axis of rotation.

A. 1, 2, 3 and 4
B. 1, 2, and 3 only
C. 2, 3 and 4 only
D. 1, 3 and 4 only
Answer» D. 1, 3 and 4 only
45.

Which of the following statements is correct about the balancing of a mechanical system?

A. if it is under static balance, then there will be dynamic balance also
B. if it is under dynamic balance, then there will be static balance also
C. both static as well as dynamic balance have to be achieved separately
D. none of the mentioned
Answer» C. both static as well as dynamic balance have to be achieved separately
46.

In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large in order to

A. minimize the effect of primary forces
B. minimize the effect of secondary forces
C. have perfect balancing
D. start the locomotive conveniently
Answer» B. minimize the effect of secondary forces
47.

Multi-cylinder engines are desirable because

A. only balancing problems are reduced
B. only flywheel size is reduced
C. both (a) and (b)
D. none of the mentioned
Answer» C. both (a) and (b)
48.

Secondary forces in reciprocating mass on engine frame are

A. of same frequency as of primary forces
B. twice the frequency as of primary forces
C. four times the frequency as of primary forces
D. none of the mentioned
Answer» B. twice the frequency as of primary forces
49.

Work produced by the 4-stroke engine is less because  

A. one power stroke per 2 revolutions
B. one power stroke per revolution
C. one power stroke per 4 revolution
D. four power stroke per revolution
Answer» A. one power stroke per 2 revolutions
50.

When the work is done on the gases, which of the following effect is observed on the turning moment diagram?

A. formation of negative loop
B. formation of positive loop
C. formation of an infinite loop
D. formation of no loop
Answer» A. formation of negative loop
51.

Compression stroke results in  

A. formation of negative loop
B. formation of positive loop
C. formation of an infinite loop
D. formation of no loop
Answer» A. formation of negative loop
52.

4 strokes engine have a lower thermal efficiency than 2 stroke engine.

A. true
B. false
Answer» B. false
53.

3 BALANCING MACHINES-FIELD BALANCING OF DISCS AND ROTORS.

A. centripetal forces
B. centrifugal forces
C. friction forces
D. inertia forces
Answer» D. inertia forces
54.

Balancing of single rotating mass by balancing masses in same plane and in different planes cannot take place.

A. true
B. false
Answer» B. false
55.

Which of the following is true for centrifugal force causing unbalance?

A. direction changes with rotation
B. magnitude changes with rotation
C. direction and magnitude both change with rotation
D. direction and magnitude both remain unchanged with rotation
Answer» A. direction changes with rotation
56.

In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of the rotor lies  

A. below the axis of shaft
B. on the axis of the shaft
C. above the axis of shaft
D. away from the axis of shaft
Answer» B. on the axis of the shaft
57.

If the unbalanced system is not set right then.

A. static forces develop
B. dynamic forces develop
C. tangential forces develop
D. radial forces develop
Answer» A. static forces develop
58.

What is not the effect of unbalanced forces?

A. load on bearings
B. dangerous vibrations
C. stresses in various members
D. violation of conservation of mass principle
Answer» D. violation of conservation of mass principle
59.

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

A. transverse vibrations
B. torsional vibrations
C. longitudinal vibrations
D. none of the mentioned
Answer» A. transverse vibrations
60.

In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be

A. less than unity
B. equal to unity
C. greater than unity
D. zero
Answer» C. greater than unity
61.

The accelerometer is used as a transducer to measure earthquake in Richter scale. Its design is based on the principle that

A. its natural frequency is very low in comparison to the frequency of vibration
B. its natural frequency is very high in comparison to the frequency of vibration
C. its natural frequency is equal to the frequency of vibration
D. measurement of vibratory motion is without any reference point
Answer» C. its natural frequency is equal to the frequency of vibration
62.

Critical speed is expressed as

A. rotation of shaft in degrees
B. rotation of shaft in radians
C. rotation of shaft in minutes
D. natural frequency of the shaft
Answer» D. natural frequency of the shaft
63.

The first critical speed of an automobile running on a sinusoidal road is calculated by (modeling it as a single degree of freedom system)

A. resonance
B. approximation
C. superposition
D. rayleigh quotient
Answer» A. resonance
64.

The natural frequency of a spring-mass system on earth is ωn. The natural frequency of this system on the moon (gmoon = gearth/6) is

A. ωn
B. 0.408ωn
C. 0.204ωn
D. 0.167ωn
Answer» A. ωn
65.

6 kN/m and the damping constant of the damper is 400 Ns/m. If the mass is 50 kg, then the damping factor (d ) and damped natural frequency (fn), respectively, are

A. 0.471 and 1.19 hz
B. 0.471 and 7.48 hz
C. 0.666 and 1.35 hz
D. 0.666 and 8.50 hz
Answer» A. 0.471 and 1.19 hz
66.

5 m/s.

A. 4.19
B. 5
C. 3.49
D. 3.36
Answer» C. 3.49
67.

Which of the following expression represent the angular acceleration α of the connecting rod?

A. −ω2 . sin θ/n
B. −ω2 . cos θ.n
C. ω2. cos θ/n
D. ω2 . sin θ.n
Answer» A. −ω2 . sin θ/n
68.

While calculating angular acceleration of the connecting rod, sin2(θ) term is neglected.

A. true
B. false
Answer» A. true
69.

In a slider crank mechanism, the length of the crank and connecting rod are 180 mm and 540 mm respectively. The crank position is 45° from inner dead centre. The crank shaft speed is 450 r.p.m. (clockwise), calculate angular velocity of the connecting rod in rad/s.

A. 10.3
B. 11.1
C. 12.2
D. 11.8
Answer» B. 11.1
70.

When a body is subjected to transverse vibrations, the stress induced in a body will be

A. shear stress
B. bending stress
C. tensile stress
D. compressive stress
Answer» B. bending stress
71.

Longitudinal 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 the mentioned
Answer» B. parallel to its axis
72.

When a body is subjected to transverse vibrations, the stress induced in a body will be

A. shear stress
B. tensile stress
C. compressive stress
D. none of the mentioned
Answer» B. tensile stress
73.

The factor which affects the critical speed of a shaft is

A. diameter of the disc
B. span of the shaft
C. eccentricity
D. all of the mentioned
Answer» D. all of the mentioned
74.

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. magnification factor
75.

Which of the following systems produce a vibration in the foundation?

A. unbalanced machine
B. balanced machine
C. coupled machine
D. uncoupled machine
Answer» A. unbalanced machine
76.

When a periodic disturbing force is applied to a machine, the force is transmitted to the foundation by the means of spring.

A. true
B. false
Answer» A. true
77.

Which of the following is a type of transmitted force to the foundation?

A. damping force
B. undamping force
C. tensile force
D. torsional force
Answer» A. damping force
78.

If the damper is not provided and the system is in resonance, which of the following is the correct isolation factor?

A. 0
B. 1/2
C. 1/4
D. infinity
Answer» D. infinity
79.

If isolation factor is negative, then what is the phase difference between transmitted and disturbing force?

A. 180°
B. 90°
C. 450°
D. 360°
Answer» A. 180°
80.

Which of the following is true regarding Ɛ>1?

A. transmitted force is greater than applied force
B. transmitted force is less than applied force
C. spring force is less than applied force
D. damping force is less than applied force
Answer» A. transmitted force is greater than applied force
81.

Isolation factor is twice the transmissibility ratio.

A. true
B. false
Answer» B. false
82.

The height of a Watt’s governor is

A. directly proportional to speed
B. directly proportional to (speed)
C. inversely proportional to speed
D. inversely proportional to (speed)
Answer» D. inversely proportional to (speed)
83.

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» C. 100 to 200 r.p.m
84.

When the sleeve of a Porter governor moves downwards, the governor speed

A. increases
B. decreases
C. remains unaffected
D. first increases and then decreases
Answer» B. decreases
85.

In a Porter governor, the balls are attached to the extension of lower links.

A. true
B. false
Answer» A. true
86.

A Hartnell governor is a

A. dead weight governor
B. pendulum type governor
C. spring loaded governor
D. inertia governor
Answer» C. spring loaded governor
87.

A Watt’s governor is a spring loaded governor.

A. true
B. false
Answer» B. false
88.

Which of the following is a pendulum type governor?

A. watt’s governor
B. porter governor
C. hartnell governor
D. none of the mentioned
Answer» A. watt’s governor
89.

A disc is a spinning with an angular velocity ω rad/s about the axis of spin. The couple applied to the disc causing precession will be

A. 1/2 iω2
B. iω2
C. 1/2 iωωp
D. iωωp
Answer» D. iωωp
90.

The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of gyroscopic couple on the aeroplane will be

A. to dip the nose and tail
B. to raise the nose and tail
C. to raise the nose and dip of the tail
D. to dip the nose and raise the tail
Answer» C. to raise the nose and dip of the tail
91.

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 side-ways
D. none of the mentioned
Answer» B. turning of a complete ship in a curve towards right or left, while it moves forward
92.

The rolling of a complete ship side-ways is known as pitching of a ship.

A. true
B. false
Answer» B. false
93.

The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a right turn. The effect of gyroscopic couple acting on it will be to raise the stern and lower the bow.

A. true
B. false
Answer» A. true
94.

The pitching of a ship is assumed to take place with simple harmonic motion.

A. true
B. false
Answer» A. true
95.

Power is transmitted by an electric motor to a machine by using a belt drive. The tensions on the tight and slack side of the belt are 2200 N and 1000 N respectively and diameter of the pulley is 600 mm. If speed of the motor is 1500 r.p.m, find the power transmitted.

A. 46.548 kw
B. 56.548 kw
C. 66.548 kw
D. 76.548 kw
Answer» B. 56.548 kw
96.

6 x 10 = 6 rad/s.

A. 2.055 m
B. 3.055 m
C. 4.055 m
D. 5.055 m
Answer» A. 2.055 m
97.

Calculate the work done per minute by a punch tool making 20 working strokes per min when a 30 mm diametre hole is punched in 5 mm thick plate with ultimate shear strength og 450 Mpa in each stroke.

A. 10.69 knm
B. 20.69 knm
C. 30.69 knm
D. 40.69 knm
Answer» A. 10.69 knm
98.

In latitude 25.0 S, SA (spin axis) of a FG (free gyro) is in position S40E and horizontal. Find the tilt after 6 hours.

A. 61.16 up
B. 61.16 down
C. 51.15 up
D. none of the mentioned
Answer» A. 61.16 up
99.

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 r left, while it moves forward
C. rolling of a complete ship sideways
D. none of the mentioned
Answer» B. turning of a complete ship in a curve towards right r left, while it moves forward
100.

When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be

A. to move the ship towards starboard
B. to move the ship towards port side
C. to raise the bow and lower the stern
D. to raise the stern and lower the bow
Answer» A. to move the ship towards starboard
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