In a flat collar pivot bearing, the moment due to friction is proportional to
(r₁² - r₂²)/(r₁ - r₂)
(r₁² - r₂²)/(r₁ + r₂)
(r₁³ - r₂³)/(r₁² - r₂²)
(r₁³ - r₂³)/(r₁ - r₂)
Correct Answer :
C. (r₁³ - r₂³)/(r₁² - r₂²)
Related Questions
Which of the following is an example of a higher pair?
Toothed gearing
Belt and rope drive
Ball and roller bearing
All of these
A typewriter mechanism has 7 numbers of binary joints, six links and none of higher pairs. The mechanism is
Kinematically sound
Not sound
Soundness would depend upon which link is kept fixed
Data is not sufficient to determine same
The type of gears used to connect two non parallel and non intersecting shafts is
Spur gear
Helical gear
Bevel gear
Spiral gear
In higher pair, the relative motion is
Purely turning
Purely sliding
Purely rotary
Combination of sliding and turning
Which is the false statement about the properties of instantaneous centre?
At the instantaneous center of rotation, one rigid link rotates instantaneously relative to another for the configuration of mechanism considered
The two rigid links have no linear velocities relative to each other at the instantaneous centre
The two rigid links which have no linear velocity relative to each other at this center have the same linear velocity to the third rigid link
The double centre can be denoted either by O2 or O12, but proper selection should be made
The ratio of height of Porter governor (when length of arms and links are equal) to the height of Watt's governor is (where m = Mass of the ball, and M = Mass on the sleeve)
m/(m + M)
M/(m + M)
(m + M)/m
(m + M)/M
A single degree of freedom system is given by, m × (d²x/dt²) + c × (dx/dt) + sx = F.cosω.t with usual notations. It represents
Free vibration with damping
Free vibration without damping
Forced vibration with damping
Forced vibration without damping
The size of a gear is usually specified by
Pressure angle
Circular pitch
Diametral pitch
Pitch circle diameter
The natural frequency of free transverse vibrations due to a point load acting over a simply supported shaft is equal to (where δ = Static deflection of a simply supported shaft due to the point load)
0.4985/√δ
0.5615/√δ
0.571/√δ
0.6253/√δ
The height of a Watt's governor (in metres) is equal to (where N = Speed of the arm and ball about the spindle axis)
8.95/N²
89.5/N²
895/N²
8950/N²
The centre of percussion is below the centre of gravity of the body and is at a distance equal to
h/kG
h²/kG
kG²/h
h × kG
A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is
5,367 r.p.m.
6,000 r.p.m.
9,360 r.p.m.
12,000 r.p.m.
A fixed gear having 200 teeth is in mesh with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of bigger gear is
2
4
3
None of the above
An eccentric sheave pivoted at one point rotates and transmits oscillatory motion to a link whose one end is pivoted and other end is connected to it. This mechanism has
2 links
3 links
4 links
5 links
The motion between a pair which takes place in __________ is known as incompletely constrained motion.
One direction only
Two directions only
More than one direction
None of these
The radial distance from the top of a tooth to the bottom of a tooth in a meshing gear, is called
Dedendum
Addendum
Clearance
Working depth
In gramophones for adjusting the speed of the turntable, the following type of governor is commonly employed
Hartung governor
Wilson Hartnell governor
Pickering governor
Inertia governor
Instantaneous center of rotation of a link in a four bar mechanism lies on
Right side pivot of this link
Left side pivot of this link
A point obtained by intersection on extending adjoining links
Cant occur
The factor which affects the critical speed of a shaft is
Diameter of disc
Span of shaft
Eccentricity
All of these
The contact ratio for gears is
Zero
Less than one
Greater than one
Infinity
The Whitworth quick return motion mechanism is formed in a slider crank chain when the
Coupler link is fixed
Longest link is a fixed link
Slider is a fixed link
Smallest link is a fixed link
When the sleeve of a Porter governor moves upwards, the governor speed
Increases
Decreases
Remain unaffected
First increases and then decreases
The moment on the pulley which produces rotation is called
Inertia
Momentum
Moment of momentum
Torque
For an involute gear, the ratio of base circle radius and pitch circle radius is equal to
sinφ
cosφ
secφ
cosecφ
At the nodal point in a shaft, the amplitude for torsional vibration will be
Minimum
Maximum
Zero
Infinity
Which of the following is an inversion of a double slider crank chain?
Oldham's coupling
Elliptical trammel
Scotch yoke mechanism
All of these
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
For dynamic balancing of a shaft
The net dynamic force acting on the shaft is equal to zero
The net couple due to the dynamic forces acting on the shaft is equal to zero
Both (A) and (B)
None of the above
The acceleration of a particle at any instant has two components i.e. radial component and tangential component. These two components will be
Parallel to each other
Perpendicular to each other
Inclined at 45°
Opposite to each other
Tangential acceleration direction is
Along the angular velocity
Opposite to angular velocity
May be any one of these
Perpendicular to angular velocity