Theory of machines

Q1: The tractive force in a locomotive with two cylinders is given by (where c = Fraction of reciprocating parts per cylinder, m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, and θ = Angle of inclination of crank to the line of stroke)

A m2.r cos θ

B c.m2.r sin θ

C (1 - c)m2.r(cos θ - sin θ)

D m2.r(cos θ - sin θ)

Q2: The radial distance of a tooth from the pitch circle to the bottom of the tooth is called

A dedendum

B addendum

C clearance

D working depth

Q3: The acceleration of the particle moving with simple harmonic motion is inversely proportional to the displacement of the particle from the mean position.

A Yes

B No

Q4: The two elements of a pair are said to form a __________ when they permit relative motion between them.

A open pair

B kinematic pair

Q5: The Whitworth quick return motion mechanism is formed in a slider crank chain when the

A coupler link is fixed

B longest link is a fixed link

C slider is a fixed link

D smallest link is a fixed link

Q6: In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if ω/ωn is

A equal to one

B equal to 2

C less than 2

D greater than 2

Q7: The partial balancing of reciprocating parts in locomotives produces

A hammer blow

B swaying couple

C variation in tractive force along the line of stroke

D all of the above

Q8: When a particle moves round the circumference of a circle of radius r with ω rad/s, then its maximum acceleration is ω2r.

A Right

B Wrong

Q9: 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

Q10: A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural bow-shaped mode, it has a frequency of vibration of 10 rad/s. When the shaft is rotated at 300 r.p.m., it will whirl with a radius of

A 2 mm

B 2.22 mm

C 2.50 mm

D 3.0 mm

Q11: The sliding pairs, turning pairs and screw pairs form lower pairs.

A True

B False

Q12: The ratio of the actual damping coefficient to the critical damping coefficient is called damping factor.

A Yes

B No

Q13: When a body moves with simple harmonic motion, the product of its periodic time and frequency is equal to

A zero

B one

C π/2

D π

Q14: The frictional torque transmitted in a multi-collared shaft is same as that of a single collared shaft.

A Right

B Wrong

Q15: In order to give the primary balance of the reciprocating parts of a multi-cylinder in-line engines,

A the algebraic sum of the primary forces must be equal to zero

B the algebraic sum of the couples about any point in the plane of the primary forces must be equal to zero

C both (a) and (b)

D none of these

Q16: The frequency of damped vibrations with viscous damping is __________ the frequency of undamped vibrations.

A more than

B less than

C same as

Q17: The pressure angle of a cam is the angle between the direction of the follower motion and a normal to the

A pitch circle

B base circle

C pitch curve

D prime circle

Q18: When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as a

A lower pair

B higher pair

C self-closed pair

D force-closed pair

Q19: The gear train usually employed in clocks is a

A simple gear train

B reverted gear train

C sun and planet gear

D differential gear

Q20: The pair is known as a higher pair, when the relative motion between the elements of a pair is

A turning only

B sliding only

C rolling only

D partly turning and partly sliding

Q21: The dynamic friction is the friction experienced by a body, when the body

A is in motion

B is at rest

C just begins to slide over the surface of the other body

D none of the above

Q22: 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 Agree

B Disagree

Q23: 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

Q24: When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be

A minimum

B zero

C maximum

D none of these

Q25: The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω1 rad/s in the clockwise direction and the link OB turns with angular velocity ω2 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 ω12.r

B ( ω1 - ω2)r

C ( ω1 + ω2)r

D ( ω1 - ω2)2r

Q26: In a screw jack, the effort required to lower the load W is given by

A P = W tan(α - φ)

B P = W tan(α + φ)

C P = W tan(φ - α)

D P = W cos(α + φ)

Q27: For a twin cylinder V-engine, the crank positions for primary reverse cranks and secondary direct cranks are shown in the below figure. The engine is a

A 30° V-engine

B 60° V-engine

C 120° V-engine

D 150° V-engine

Q28: In under damped vibrating system, the amplitude of vibration

A decreases linearly with time

B increases linearly with time

C decreases exponentially with time

D increases exponentially with time

Q29: The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke (θ) is equal to

A 90° and 180°

B 45° and 225°

C 180° and 270°

D 270° and 360°

Q30: A mass of 1 kg is attached to the end of a spring with a stiffness of 0.7 N/mm. The critical damping coefficient of this system is

A 1.4 N-s/m

B 18.52 N-s/m

C 52.92 N-s/m

D 529.2 N-s/m

Q31: The cam follower generally used in automobile engines is

A knife edge follower

B fiat faced follower

C spherical faced follower

D roller follower

Q32: When the relation between the controlling force (Fc) and radius of rotation (r) for a spring controlled governor is Fc = ar + b, then the governor will be

A stable

B unstable

C isochronous

D none of these

Q33: The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is

A 0° and 90°

B 0° and 180°

C 90° and 180°

D 180° and 360°

Q34: 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 above

Q35: In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon

A total lift, total angle of lift, minimum radius of cam and cam speed

B radius of circular arc, cam speed, location of centre of circular arc and roller diameter

C mass of cam follower linkage, spring stiffness and cam speed

D total lift, centre of gravity of the cam and cam speed

Q36: A pair of friction discs is an example of rolling pair.

A True

B False

Q37: When the connection between the two elements is such that only required kind of relative motion occurs, it is known as self-closed pair.

A Right

B Wrong

Q38: When the axes of the shafts, over which the gears are mounted, move relative to a fixed axis, then the train is known as reverted gear train.

A Right

B Wrong

Q39: Whitworth quick return motion mechanism consists of three turning pairs and one sliding pair.

A Right

B Wrong

Q40: If ω/ωn 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

B 90°

C 180°

D 360°

Q41: 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

Q42: The centre distance between two meshing involute gears is equal to

A

B

C

D

Q43: If ω/ωn = 2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will the

A 0.5

B 1

C 1.5

D 2

Q44: The factor which affects the critical speed of a shaft is

A diameter of disc

B span of shaft

C eccentricity

D all of these

Q45: An automobile steering gear is an example of

A sliding pair

B rolling pair

C lower pair

D higher pair

Q46: The gears are termed as medium velocity gears, if their peripheral velocity is

A 1 - 3 m/s

B 3 - 15 m/s

C 15 - 30 m/s

D 30 - 50 m/s

Q47: In order to balance the reciprocating masses,

A primary forces and couples must be balanced

B secondary forces and couples must be balanced

C both (a) and (b)

D none of these

Q48: In a vibrating system, if the actual damping coefficient is 40 N/m/s and critical damping coefficient is 420 N/m/s, then logarithmic decrement is equal to

A 0.2

B 0.4

C 0.6

D 0.8

Q49: 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)

A m1r2 = m2r1

B m1r1 = m2r2

C m1m2 = r1r2

D none of these

Q50: In a coupling rod of a locomotive, each of the four pairs is a __________ pair.

A sliding

B turning

C rolling

D screw


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