# Multiple choice question for engineering

## Set 1

1. The advantages of the V-belt drive over flat belt drive are

a) The V-belt drive gives compactness due to the small distance between the centres of pulleys.

b) The drive is positive, because the slip between the belt and the pulley groove is negligible.

c) Since the V-belts are made endless and there is no joint trouble, therefore the drive is smooth.

d) all of the mentioned

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2. The disadvantages of the V-belt drive over flat belt drive are

a) The V-belt drive cannot be used with large centre distances.

b) The V-belts are not so durable as flat belts.

c) The construction of pulleys for V-belts is more complicated than pulleys for flat belts.

d) all of the mentioned

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3. The advantages of the V-belt drive over flat belt drive are

a) It provides longer life, 3 to 5 years.

b) It can be easily installed and removed.

c) The operation of the belt and pulley is quiet.

d) all of the mentioned

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4. The disadvantages of the V-belt drive over flat belt drive are

a) Since the V-belts are subjected to certain amount of creep, therefore these are not suitable for constant speed application such as synchronous machines, and timing devices.

b) The belt life is greatly influenced with temperature changes, improper belt tension and mismatching of belt lengths.

c) The centrifugal tension prevents the use of V-belts at speeds below 5 m/s and above 50m/s.

d) all of the mentioned

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5. The distance between the hinge centre of a link and the corresponding hinge centre of the adjacent link is called

a) pitch of the chain

b) bush roller chain

c) block chain

d) none of the mentioned

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6. Industrial rotors will not have uniform diameter throughout their lengths.

a) True

b) False

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7. For cutting multi-start threads, the speed ratio is expressed in terms of the lead of the job thread and lead of the lead screw threads.

a) True

b) False

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8. Which one of the following is a positive drive?

a) Crossed flat belt drive

b) Rope drive

c) V-belt drive

d) Chain drive

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9. The chain drive transmits ____________ power as compared to belt drive.

a) more

b) less

c) equal

d) none of the mentioned

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10. The relation between the pitch of the chain (p) and pitch circle diameter of the sprocket (D) is given by

a) p = D sin(90^{0}/T)

b) p = D sin(120^{0}/T)

c) p = D sin(180^{0}/T)

d) p = D sin(360^{0}/T)

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11. In order to have smooth operation, the minimum number of teeth on the smaller sprocket, for moderate speeds, should be

a) 15

b) 17

c) 21

d) 25

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12. The speed of the sprocket reduces as the chain pitch _____________ for a given number of teeth.

a) increases

b) decreases

c) remains same

d) none of the mentioned

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13. The greater angle of articulation will increase the life of the chain.

a) True

b) False

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## Set 2

1. The velocity ratio of two pulleys connected by an open belt or crossed belt is

a) directly proportional to their diameters

b) inversely proportional to their diameters

c) directly proportional to the square of their diameters

d) inversely proportional to the square of their diameters

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_{1}= Diameter of the driver, d

_{2}= Diameter of the follower, N

_{1}= Speed of the driver in r.p.m., and N

_{2}= Speed of the follower in r.p.m. ∴ Length of the belt that passes over the driver, in one minute = π d

_{1}.N

_{1}Similarly, length of the belt that passes over the follower, in one minute = π d

_{2}. N

_{2}Since the length of belt that passes over the driver in one minute is equal to the length of belt that passes over the follower in one minute, therefore π d

_{1}.N

_{1}= π d

_{2}. N

_{2}∴ Velocity ratio, N

_{2}/N

_{1}= d

_{1}/d

_{2}.

2. Two pulleys of diameters d_{1} and d_{2} and at distance x apart are connected by means of an open belt drive. The length of the belt is

a) π /2 (d_{1} + d_{2}) 2x + (d_{1} + d_{2})^{2}/4x

b) π /2 (d_{1} – d_{2}) 2x + (d_{1} – d_{2})^{2}/4x

c) π /2 (d_{1} + d_{2}) 2x + (d_{1} – d_{2})^{2}/4x

d) π /2 (d_{1} – d_{2}) 2x + (d_{1} + d_{2})^{2}/4x

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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) cross belt drive is recommended

c) both open belt drive and cross belt drive are recommended

d) the drive is recommended depending upon the torque transmitted

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4. Due to slip of the belt, the velocity ratio of the belt drive

a) decreases

b) increases

c) does not change

d) none of the mentioned

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5. When two pulleys of different diameters are connected by means of an open belt drive, then the angle of contact taken into consideration should be of the

a) larger pulley

b) smaller pulley

c) average of two pulleys

d) none of the mentioned

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6. The power transmitted by a belt is maximum when the maximum tension in the belt (T) is equal to

a) T_{C}

b) 2T_{C}

c) 3T_{C}

d) 4T_{C}

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_{C}where T

_{C}= Centrifugal tension.

7. The velocity of the belt for maximum power is

a) √T/3m

b) √T/4m

c) √T/5m

d) √T/6m

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_{1}= T– T

_{C}and for maximum power T

_{C}= T/3 T

_{1}= T – T/3 = 2T/3

the velocity of the belt for the maximum power, v = √T/3m where m = Mass of the belt in kg per metre length.

8. The centrifugal tension in belts

a) increases power transmitted

b) decreases power transmitted

c) have no effect on the power transmitted

d) increases power transmitted upto a certain speed and then decreases

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9. 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 in the tight side and slack side of the belt

d) average tension of the tight side and slack side of the belt

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10. The relation between the pitch of the chain ( p) and pitch circle diameter of the sprocket (d) is given by

a) p = d sin (60^{0}/T)

b) p = d sin (90^{0}/T)

c) p = d sin (120^{0}/T)

d) p = d sin (180^{0}/T)

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^{0}/T).

## Set 3

1. The bevel gears are used to connect

a) two parallel shafts

b) two intersecting shafts

c) two non intersecting shafts

d) none of the mentioned

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2. Bevel gears with shafts angle of 90^{0} are termed as

a) zerol gears

b) angular bevel gears

c) mitre gears

d) hypoid gears

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^{0}are termed as Mitre gears. The bevel gears with any other shaft angle are termed as angular bevel gears.

3. The bevel gears used for connecting non intersecting shafts are

a) mitre gears

b) hypoid gears

c) spiral bevel gears

d) zerol gears

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^{0}are termed as Mitre gears.

4. Face width of the bevel gear is usually equal to

a) 10 modules

b) pitch cone radius/3

c) pitch cone radius/2

d) none of the mentioned

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5. Formative number of teeth on bevel gears is equal to

a) 2 x actual number of teeth

b) actual number of teeth/ cosɸ

c) actual number of teeth/cosα

d) actual number of teeth/cosϴ

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6. Lewis Equation for bevel gear is corrected for

a) variation in p.c.d.

b) variation in tooth thickness

c) taking care of axial thrust

d) variation in torque acting on the tooth

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7. Ratio factor Q in wear load equation of bevel gear is given by

a) 2gear ratio G/G + 1

b) 2ratio of formative number of teeth of gear and pinion G

c) G + 1/G^{‘} +1

d) 2G^{‘}/G

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8. Bevel factor should not be less than

a) 0.75

b) 0.8

c) 0.67

d) 0.76

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9. Pitch cone angle of pinion of straight tooth bevel gear pair with ratio 1.732 is

a) 25^{0}

b) 30^{0}

c) 60^{0}

d) none of the mentioned

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10. The face width of the bevel gear is 0.3 times the radius of pitch cone. Here the bevel factor must be

a) 1.3

b) 3

c) 0.7

d) 1.7

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11. Interchangibility is possible only in

a) bevel gear

b) helical gear

c) spur gear

d) mitre gear

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## Set 4

1. In S.H.M., acceleration is proportional to

a) velocity

b) displacement

c) rate of change of velocity

d) none of the mentioned

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2. In S.H.M., the velocity vector w.r.t. displacement vector

a) leads by 90^{0}

b) lags by 90^{0}

c) leads by 180^{0}

d) none of the mentioned

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3. A body having moment of inertia of 30 kg m^{2} is rotating at 210 RPM and mashes with another body at rest having M.I. of 40 kg m^{2}. The resultant speed after meshing will be

a) 90 RPM

b) 100 RPM

c) 80 RPM

d) none of the mentioned

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30 x 210 = 40 x Resultant speed or, Resultant speed = 90 RPM.

4. Inertia force acts

a) perpendicular to the accelerating force

b) along the direction of accelerating force

c) opposite to the direction of accelerating force

d) none of the mentioned

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5. The frequency of oscillation at moon compared to earth will be

a) 6 times more

b) 6 times less

c) 2.44 times more

d) 2.44 times less

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6. Polar moment of inertia(I_{P}) of a circular disc is to be determined by suspending it by a wire and noting the frequency of oscillations(f)

a) I_{P} ∞ f

b) I_{P} ∞ f^{2}

c) I_{P} ∞ 1/f^{2}

d) none of the mentioned

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7. The frequency of oscillation of a bigger diameter cylinder compared to a small cylinder inside a cylinder concave surface will be

a) less

b) more

c) same

d) none of the mentioned

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8. The frequency of oscillation of a cylinder inside a cylinder inside a cylindrical concave surface of bigger radius compared to a small radius will be

a) less

b) more

c) same

d) none of the mentioned

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9. If the radius of gyration of a compound pendulum about an axis through c.g. is more, then its frequency of oscillation will be

a) less

b) more

c) same

d) none of the mentioned

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10. The Bifilar suspension method is used to determine

a) natural frequency of vibration

b) position of balancing weights

c) moment of inertia

d) none of the mentioned

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11. The natural frequency of a spring-mass system on earth is ω_{n}. The natural frequency of this system on the moon (g_{moon} =g_{earth}/6) is

a) ω_{n}

b) 0.408ω_{n}

c) 0.204ω_{n}

d) 0.167ω_{n}

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_{n}= √k/m ………………….(i) This equation (i) does not depend on the g and weight (W = mg) So, the natural frequency of a spring mass system is unchanged on the moon. Hence, it will remain ωn , i.e. ω

_{moon}=ω

_{n}.

12. An automotive engine weighing 240 kg is supported on four springs with linear characteristics. Each of the front two springs have a stiffness of 16MN/m while the stiffness of each rear spring is 32MN/m. The engine speed (in rpm), at which resonance is likely to occur, is

a) 6040

b) 3020

c) 1424

d) 955

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_{1}= k

_{2}= 16MN/m, k

_{3}= k

_{4}= 32MN/m, m = 240 kg Here, k

_{1}& k

_{2}are the front two springs or k

_{3}and k

_{4}are the rear two springs. These 4 springs are parallel, So equivalent stiffness k

_{eq}= k

_{1}+ k

_{2}+ k

_{3}+ k

_{4}= 16 + 16 + 32 + 32 = 96MN/m

^{2}We know at resonance ω = ω

_{n}= √k/m 2πN/60 = √k

_{eq}/m N =Engine speed in rpm

N = 60/2π√k_{eq}/m
= 60/2π√96 x 10^{6}/240
= 6040 rpm.

13. A vehicle suspension system consists of a spring and a damper. The stiffness of the spring is 3.6 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 (f_{n}), 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

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_{n}= √k/m = 8.485 rad/ sec And damping factor is given by, d or ε = c/c

_{c}= 0.471 Damping Natural frequency, ω

_{d}= √1 – ε

^{2}ω

_{n}2πf

_{d}= √1 – ε

^{2}ω

_{n}f

_{d}= 1.19 Hz.

14. For an under damped harmonic oscillator, resonance

a) occurs when excitation frequency is greater than undamped natural frequency

b) occurs when excitation frequency is less than undamped natural frequency

c) occurs when excitation frequency is equal to undamped natural frequency

d) never occurs

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_{d}= ω

_{n}.

15. A vibratory system consists of a mass 12.5 kg, a spring of stiffness 1000N/m , and a dash-pot with damping coefficient of 15 Ns/m.The value of critical damping of the system is

a) 0.223 Ns/m

b) 17.88 Ns/m

c) 71.4 Ns/m

d) 223.6 Ns/m

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_{c}= 2m√k/m = 2√km On substituting the values, we get c

_{c}= 223.6 Ns/m.

## Set 5

1. A side and face cutter 125 mm diameter has 10 teeth. It operates at a cutting speed of 14 m/min with a table traverse 100 mm/min. The feed per tooth of the cutter is

a) 10 mm

b) 2.86 mm

c) 0.286 mm

d) 0.8 mm

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2. Consider the following statements in case of reverted gear train:

1. The direction of rotation of the first and the last gear is the same.

2. the direction of rotation of the first and the last gear is opposite.

3. The first and the last gears are on the same shaft.

4. The first and the last gears are on separate but co-axial shafts.

Which of these statements is/are correct?

a) 1 and 3

b) 2 and 3

c) 2 and 4

d) 4 alone

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3. The dynamic load on a gear is due to

1. inaccurancies of tooth spacing

2. irregularities in tooth profile

3. deflection of the teeth under load

4. type of service

Which of the above statements are correct?

a) 1,2 and 3

b) 2,3 and 4

c) 1,3 and 4

d) 1,2 and 4

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4. Consider the following statements:

A 20^{0} stub tooth system is generally preferred in spur gears as it results in

1. stronger teeth

2. lesser number of teeth on the pinion

3. lesser chances of surface fatigue failure

4. reduction of interference

Which of the above statements are correct?

a) 1,2 and 4

b) 3 and 4

c) 1 and 3

d) 1,2,3 and 4

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^{0}stub tooth system is generally preferred in spur gears as it results in 1. stronger teeth 2. lesser number of teeth on the pinion 3. reduction of interference.

5. An involute rack with 20^{0} pressure angle meshes with a pinion of 14.5^{0} pressure angle.

a) True

b) False

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6. When a pair of spur gears of the same material is in mesh, the design is based on pinion.

a) True

b) False

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7. Consider the following modifications regarding avoiding the interference between gears:

1. The centre distance between meshing gears be increased

2. Addendum of the gear be modified

3. Teeth should be undercut slightly at the root

4. Pressure angle should be increased

5. Circular pitch be increased

Which of these are effective in avoiding interference?

a) 1,2 and 3

b) 2,3,4 and 5

c) 1,4 and 5

d) 3,4 and 5

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8. In a reverted gear train, two gears P and Q are meshing, Q-R is a compound gear, and R and S are meshing. The modules of P and R are 4 mm and 5 mm respectively. The numbers of teeth in P, Q and r are 20, 40 and 25 respectively. The number of teeth in S is

a) 23

b) 35

c) 50

d) 53

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_{1}(z

_{p}+ z

_{q}) = 1/2m

_{2}(z

_{r}+ z

_{s}) 4(20 + 40) = 5(25 + z

_{s}) z

_{s}= 23.

9. When two spur gears having involute profiles on their teeth engage, the line of action is tangential to the

a) pitch circles

b) dedendum circles

c) addendum circles

d) base circles

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10. If the annular wheel of an epicyclic gear train has 100 teeth and the planet wheel has 20 teeth, the number of teeth on sun wheel is

a) 80

b) 60

c) 40

d) 20

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_{p}+ d

_{s}= d

_{a}2z

_{p}+ z

_{s}= z

_{a}2 x 20 + z

_{s}= 100 z

_{s}= 60.