Theory of machines Paper set for practice

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Theory of machines Paper Set 1

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

1 zero

2 one

3 π/2

4 π

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

1 0.2

2 0.4

3 0.6

4 0.8

For high speed engines, the cam follower should move with

1 uniform velocity

2 simple harmonic motion

3 uniform acceleration and retardation

4 cycloidal motion

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

1 sliding

2 turning

3 rolling

4 screw

If ω/ω_n is very high for a body vibrating under steady state vibrations, the phase angle for all values of damping factors, will tend to approach

1 0°

2 90°

3 180°

4 360°

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

1 stable

2 unstable

3 isochronous

4 none of these

The partial balancing of reciprocating parts in locomotives produces

1 hammer blow

2 swaying couple

3 variation in tractive force along the line of stroke

4 all of the above

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)

1 ω1.ω2.r

2 ( ω1 - ω2)r

3 ( ω1 + ω2)r

4 ( ω1 - ω2)2r

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

1 0.5

2 1

3 1.5

4 2

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)

1 m1r2 = m2r1

2 m1r1 = m2r2

3 m1m2 = r1r2

4 none of these

In railway axle boxes, the bearing used is

1 deep groove ball bearing

2 double row self-aligning ball bearing

3 double row spherical roller bearing

4 cylindrical roller bearing

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

1 turning only

2 sliding only

3 rolling only

4 partly turning and partly sliding

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

1 coupler link is fixed

2 longest link is a fixed link

3 slider is a fixed link

4 smallest link is a fixed link

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

1 is in motion

2 is at rest

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

4 none of the above

The steering of a ship means

1 movement of a complete ship up and down in vertical plane about transverse axis

2 turning of a complete ship in a curve towards right or left, while it moves forward

3 rolling of a complete ship side-ways

4 none of the above

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)

1 m.ω2.r cos θ

2 c.m.ω2.r sin θ

3 (1 - c)m.ω2.r(cos θ - sin θ)

4 m.ω2.r(cos θ - sin θ)

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

1 dedendum

2 addendum

3 clearance

4 working depth

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

1 minimum

2 zero

3 maximum

4 none of these