4

# Which of the following statements regarding laws governing the friction between dry surfaces are correct?

The friction force is dependent on the materials of the contact surfaces.

The friction force is directly proportional to the normal force.

The friction force is independent of me area of contact.

All of the above

D. All of the above

4

# 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)

m.ω².r cosθ

c.m.ω².r sinθ

(1 - c).m.ω².r (cosθ - sinθ)

m.ω².r (cosθ - sinθ)

4

Maximum

Minimum

Zero

None of these

4

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

Is in motion

Is at rest

Just begins to slide over the surface of the other body

None of the above

4

# Angle of descent of cam is defined as the angle

During which the follower returns to its initial position

Of rotation of the cam for a definite displacement of the follower

Through which the cam rotates during the period in which the follower remains in the highest position

Moved by the cam from the instant the follower begins to rise, till it reaches its highest position

4

# The contact ratio is given by

(Length of the path of approach)/(Circular pitch)

(Length of path of recess)/(Circular pitch)

(Length of the arc of contact)/(Circular pitch)

(Length of the arc of approach)/cosφ

4

A straight line

A circle

Involute

Cycloidal

4

Equal to 1

Less than 2

Equal to 2

Greater than 2

4

W sinθ

W cosθ

W tanθ

W cosecθ

4

Slider crank

Connecting rod

Gudgeon pin

4

0.4985/ √δS

0.5615/ √δS

0.571/ √δS

0.6253/ √δS

4

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

Incompletely constrained motion

Partially constrained motion

Completely constrained motion

Successfully constrained motion

4

Lower pair

Higher pair

Turning pair

Sliding pair

4

90°

180°

360°

4

10°

14°

20°

30°

4

# The load cup of a screw jack is made separate from the head of the spindle to

Enhance the load carrying capacity of the jack

Reduce the effort needed for lifting the working load

Reduce the value of frictional torque required to be countered for lifting the load

Prevent the rotation of load being lifted

4

1.4 N-s/m

18.52 N-s/m

52.92 N-s/m

529.2 N-s/m

4

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

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

Radius of circular arc, cam speed, location of centre of circular arc and roller diameter

Mass of cam follower linkage, spring stiffness and cam speed

Total lift, centre of gravity of the cam and cam speed

4

# Which of the following disciplines provides study of relative motion between the parts of a machine?

Theory of machines

Applied mechanics

Mechanisms

Kinematics

4

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

Increases

Decreases

Remain unaffected

First increases and then decreases

4

# Effort of a governor is the

Mean force exerted at the sleeve for a given percentage change of speed

Workdone at the sleeve for maximum equilibrium speed

Mean force exerted at the sleeve for maximum equilibrium speed

None of the above

4

One

Two

Four

Six

4

Remains constant

Decreases

Increases

None of these

4

# The example of spherical pair is

Bolt and nut

Ball and socket joint

Ball bearing and roller bearing

4

# In a single slider crank chain

Each of the four pairs is a turning pair

One is a turning pair and three are sliding pairs

Two are turning pairs and two are sliding pairs

Three are turning pairs and one is a sliding pair

4

# When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will

Oscillate with increasing time period

Oscillate with decreasing amplitude

Oscillate with constant amplitude

4

Zero

One

π/2

π

4

# Coriolis component acts

Perpendicular to sliding surfaces

Along sliding surfaces

Somewhere in between above two

None of the above

4

# The centre of gravity of a coupler link in a four bar mechanism will experience

No acceleration

Only linear acceleration

Only angular acceleration

Both linear and angular acceleration

4

# In elliptical trammels

All four pairs are turning

Three pairs turning and one pair sliding

Two pairs turning and two pairs sliding

One pair turning and three pairs sliding