The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
Static friction
Dynamic friction
Limiting friction
Coefficient of friction
Correct Answer :
C. Limiting friction
Related Questions
Consider the following mechanisms:
1. Oscillating cylinder engine mechanism
2. Toggle mechanism
3. Radial cylinder engine mechanism
4. Quick return mechanism Which of the above are inversions of slider crank mechanism?
1, 2 and 4
2, 3 and 4
1, 2 and 3
1, 3 and 4
Kinematic pairs are those which have two elements that
Have line contact
Have surface contact
Permit relative motion
Are held together
The indicator using Watt mechanism is known as
Thompson indicator
Richard indicator
Simplex indicator
Thomson indicator
The length of a simple pendulum which gives the same frequency as the compound pendulum, is
kG + l₁
kG² + l₁
(kG² + l₁²)/ l₁
(kG + l₁²)/ l₁
A combination of kinematic pairs, joined in such a way that the relative motion between the links is completely constrained, is called a
Structure
Mechanism
Kinematic chain
Inversion
The critical speed of a shaft in revolution per second is __________ as that of natural frequency of transverse vibration.
Same
Different
Unpredictable
None of these
Which of the following statement is correct for gears?
The addendum is less than the dedendum
The pitch circle diameter is the product of module and number of teeth
The contact ratio means the number of pairs of teeth in contact
All of the above
The locus of a point on a thread unwound from a cylinder will be
A straight line
A circle
Involute
Cycloidal
The pitching of a ship produces forces on the bearings which act __________ to the motion of the ship.
Vertically and parallel
Vertically and perpendicular
Horizontally and parallel
Horizontally and perpendicular
The factional torque for square thread at the mean radius r while raising load W is given by
T = W.r tan(φ - α)
T = W.r tan(φ + α)
T = W.r tanα
T = W.r tanφ
Relationship between the number of links (L) and number of pairs (P) is
P = 2L - 4
P = 2L + 4
P = 2L + 2
P = 2L - 2
If the rotating mass of a rim type flywheel is distributed on another rim type flywheel whose mean radius is half the mean radius of the former, then energy stored in the latter at the same speed will be
Four times the first one
Same as the first one
One fourth of the first one
One and a half times the first one
In a locomotive, the maximum magnitude of the unbalanced force along the perpendicular to the line of stroke, is known as
Tractive force
Swaying couple
Hammer blow
None of these
The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in
Transverse vibrations
Torsional vibrations
Longitudinal vibrations
All of these
There are six gears A, B, C, D, E and F in a compound train. The numbers of teeth in the gears are 20, 60, 30, 80, 25 and 75 respectively. The ratio of angular speeds of the driven (F) to the driver (A) of the drive is
1/24
1/8
4/15
12
Kinematic pairs are those which have
Two elements held together mechanically
Two elements having relative motion
Two elements having Coriolis component
Minimum of two instantaneous centres
The working depth of a gear is the radial distance from the
Pitch circle to the bottom of a tooth
Pitch circle to the top of a tooth
Top of a tooth to the bottom of a tooth
Addendum circle to the clearance circle
If some links are connected such that motion between them can take place in more than one direction, it is called
Incompletely constrained motion
Partially constrained motion
Completely constrained motion
Successfully constrained motion
Which of the following statement is correct as regard to the difference between a machine and a structure?
The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another
The links of a machine may transmit both power and motion, whereas the members of a structure transmit forces only
A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work
All of the above
The rotating shafts tend to vibrate violently at whirling speeds because
The system is unbalanced
Bearing centre line coincides with the axis
The shafts are rotating at very high speeds
Resonance is caused due to the heavy mass of the rotor
The stress induced in a body will be shear stress, when it is subjected to
Longitudinal vibrations
Transverse vibrations
Torsional vibrations
None of these
The contact ratio for gears is
Zero
Less than one
Greater than one
Infinity
Two systems shall be dynamically equivalent when
The mass of two are same
C.G. of two coincides
M.I. of two about an axis through e.g. is equal
All of the above
Any point on a link connecting double slider crank chain will trace a
Straight line
Circle
Ellipse
Parabola
Which of the following is an inversion of a single slider crank chain?
Pendulum pump
Oscillating cylinder engine
Rotary internal combustion engine
All of these
In an open pair, the two elements of a pair
Have a surface contact when in motion
Have a line or point contact when in motion
Are kept in contact by the action of external forces, when in motion
Are not held together mechanically
Cam size depends upon
Base circle
Pitch circle
Prime circle
Outer circle
A shaft carrying two rotors at its ends will have
No node
One node
Two nodes
Three nodes
The centrifugal tension in belts
Increases power transmitted
Decreases power transmitted
Have no effect on power transmitted
Increases power transmitted upto a certain speed and then decreases
The power transmitted by a belt is maximum when the maximum tension in the belt is _________ of centrifugal tension.
One-third
Two-third
Double
Three times