When the elements of a pair are kept in contact by the action of external forces, the pair is said to be a
Lower pair
Higher pair
Self-closed pair
Force-closed pair
Correct Answer :
D. Force-closed pair
Related Questions
Under logarithmic decrement, the amplitude of successive vibrations are
Constant
In arithmetic progression
In geometric progression
In logarithmic progression
In vibration isolation system, if ω/ωn > 1, then the phase difference between the transmitted force and the disturbing force is
0°
90°
180°
270°
For the brake to be self locking, the force P at C shown in the below figure, should 
Be zero
Act in upward direction
Act in downward direction
None of these
A disc is a spinning with an angular velocity ω rad/s about the axis of spin. The couple applied to the disc causing precession will be (where I = Mass moment of inertia of the disc, and ωP = Angular velocity of precession of the axis of spin)
(1/2).Iω²
Iω²
(1/2). I ω ωP
I ω ωP
In multi V-belt transmission, if one of the belt is broken, we have to change the
Broken belt
Broken belt and its adjacent belts
All the belts
There is no need of changing any one as remaining belts can take care of transmission of load
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 mechanism consisting of three turning pairs and one sliding pair, is called a
Single slider crank chain
Whitworth quick return motion mechanism
Crank and slotted lever quick return motion mechanism
All of the above
A circle passing through the pitch point with its center at the center of cam axis is known as
Pitch circle
Base circle
Prime circle
Outer circle
Two pulleys of radii r₁ and r₂ and at distance x apart are connected by means of a cross belt drive. The length of the belt is
π (r₁ + r₂) + [(r₁ + r₂)²/x] + 2x
π (r₁ + r₂) + [(r₁ - r₂)²/x] + 2x
π (r₁ - r₂) + [(r₁ - r₂)²/x] + 2x
π (r₁ - r₂) + [(r₁ + r₂)²/x] + 2x
In a steam engine, the distance by which the outer edge of the Dslide valve overlaps the steam port is called
Lead
Steam lap
Exhaust lap
None of these
According to Kennedy's theorem, if three bodies move relatively to each other, their instantaneous centres will lie on a
Straight line
Parabolic curve
Triangle
Rectangle
The efficiency of a screw jack is maximum, when (where α = Helix angle, and φ = Angle of friction)
α = 45° + φ/2
α = 45° - φ/2
α = 90° + φ
α = 90° - φ
A higher pair has__________.
Point contact
Surface contact
No contact
None of the above
A machine mounted on a single coil spring has a period of free vibration of tp . If the spring is cut into four equal parts and placed in parallel and the machine is mounted on them, then the period of free vibration of the new system will become
tp /16
tp /4
4 tp
16 tp
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
2 mm
2.22 mm
2.50 mm
3.0 mm
The contact ratio is the ratio of
Length of pair of contact to the circular pitch
Length of arc of contact to the circular pitch
Length of arc of approach to the circular pitch
Length of arc of recess to the circular pitch
The velocity of a body moving with simple harmonic motion is __________ at the mean position.
Zero
Minimum
Maximum
None of these
In full depth involute system, the smallest number of teeth in a pinion which meshes with rack without interference is
12
16
25
32
A mechanism __________ for transmitting or transforming motion.
Can be used
Cannot be used
Unpredictable
None of these
The example of completely constrained motion is a
Motion of a piston in the cylinder of a steam engine
Motion of a square bar in a square hole
Motion of a shaft with collars at each end in a circular hole
All of the above
When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
Minimum
Zero
Maximum
None of these
For fluctuating loads, well suited bearing is
Ball bearing
Roller bearing
Needle roller bearing
Thrust bearing
The arrangement is called bevel gearing, when two __________ are connected by gears.
Intersecting and coplanar shafts
Nonintersecting and non-coplanar shafts
Parallel and coplanar shafts
Parallel and non-coplanar shafts
In a shaper mechanism, the Coriolis component of acceleration will
Not exist
Exist
Depend on position of crank
None of the above
A reed type tachometer use the principle of
Longitudinal vibration
Torsional vibration
Transverse vibration
Damped free vibration
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
The unbalanced force due to reciprocating masses
Varies in magnitude but constant in direction
Varies in direction but constant in magnitude
Varies in magnitude and direction both
Constant in magnitude and direction both
The angle of inclination of the plane, at which the body begins to move down the plane is called
Angle of friction
Angle of repose
Angle of projection
None of these
In a Hartnell governor, the compression of the spring is __________ the lift of the sleeve.
Equal to
Less than
Greater than
None of these
A completely constrained motion can be transmitted with.
1 link with pin joints
2 links with pin joints
3 links with pin joints
4 links with pin joints