The relation l = (2/3).(j + 2) apply only to kinematic chains in which lower pairs are used. This may be used to kinematic chains in which higher pairs are used, but each higher pair may be taken as equivalent to
One lower pair and two additional links
Two lower pairs and one additional link
Two lower pairs and two additional links
Any one of these
Correct Answer :
B. Two lower pairs and one additional link
Related Questions
The frictional torque transmitted in a flat pivot bearing, considering uniform wear, is (where μ = Coefficient of friction, W = Load over the bearing, and R = Radius of bearing surface)
(1/2) μ W R
(2/3) μ W R
(3/4) μ W R
μ W R
According to Kennedy's theorem, if three bodies have plane motions, their instantaneous centers lie on
A triangle
A point
Two lines
A straight line
The sense of coriolis component 2 ωv is same as that of the relative velocity vector v rotated at
45° in the direction of rotation of the link containing the path
45° in the direction opposite to the rotation of the link containing the path
90° in the direction of rotation of the link containing the path
180° in the direction opposite to the rotation of the link containing the path
Hart mechanism has
Eight links
Six links
Four links
Twelve links
TJIE horse power transmitted by a belt is dependent upon
Tension on tight side of belt
Tension on slack side of belt
Radius of pulley
All of the above
It is required to connect two parallel shafts, the distance between whose axes is small and variable. The shafts are coupled by
Universal joint
Knuckle joint
Oldham's coupling
Flexible coupling
Which of the following property of the instantaneous centre is correct?
A rigid link rotates instantaneously relative to another link at the instantaneous centre for the configuration of the mechanism considered.
The two rigid links have no linear velocity relative to each other at the instantaneous centre.
The velocity of the instantaneous centre relative to any third rigid link is same whether the instantaneous centre is regarded as a point on the first rigid link or on the second rigid link.
All of the above
The magnitude of linear velocity of a point B on a link AB relative to point A is (Where ω = Angular velocity of the link AB)
ω × AB
ω × (AB)²
ω² × AB
(ω × AB)²
Sense of tangential acceleration of a link
Is same as that of velocity
Is opposite to that of velocity
Could be either same or opposite to velocity
Is perpendicular to that of velocity
When the crank is at the inner dead centre, in a reciprocating steam engine, then the acceleration of the piston will be
ω²r. (n + 1)/n
ω²r. (n - 1)/n
ω²r. n/(n + 1)
ω²r. n/(n - 1)
The condition for correct steering of a Davis steering gear is (where α = Angle of inclination of the links to the vertical)
sinα = b/c
cosα = c/b
tanα = c/2b
cotα = c/2b
Elements of pairs held together mechanically is known as
Closed pair
Open pair
Mechanical pair
Rolling pair
In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where μ = Coefficient of friction between the blocks and the drum, θ = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)
T₁/T₂ = μ. θ. n
T₁/T₂ = [(1 - μ tanθ)/(1 + μ tanθ)]n
T₁/T₂ = (μ θ)n
T₁/T₂ = [(1 + μ tanθ)/(1 - μ tanθ)]n
Kinematic pairs are those which have two elements that
Have line contact
Have surface contact
Permit relative motion
Are held together
The lower pair is a
Open pair
Closed pair
Sliding pair
Point contact pair
Which of the following disciplines provides study of relative motion between the parts of a machine?
Theory of machines
Applied mechanics
Mechanisms
Kinematics
Governor is used in automobile to
Decrease the variation of speed
Maximize the fuel economy
Limit the vehicle speed
Maintain constant engine speed
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
In full depth involute system, the smallest number of teeth in a pinion which meshes with rack without interference is
12
16
25
32
The velocity of sliding of meshing gear teeth is (Where ω₁ and ω₂ are angular velocities of meshing gears and y is distance between point of contact and the pitch point)
(ω₁ + ω₂)y
(ω₁/ω₂)y
(ω₁ × ω₂)y
(ω₁ + ω₂)/y
For an isochronous Hartnell governor (where r₁ and r₂ = Maximum and minimum radius of rotation of balls respectively, S₁ and S₂ = Maximum and minimum force exerted on the sleeve respectively, and M = Mass on the sleeve)
(m.g + S₁)/(m.g + S₂) = r₁/r₂
(m.g - S₁)/(m.g - S₂) = r₂/r₁
S₁/S₂ = r₁/r₂
S₂/S₁ = r₁/r₂
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
Two pulleys of radii r₁ and r₂ and at distance x apart are connected by means of an open 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
The velocity of piston in a reciprocating steam engine is given by (where ω = Angular velocity of crank, r = Radius of crank pin circle, θ = Angle turned by crank from inner dead centre, and n = Ratio of length of connecting rod to the radius of crank)
ωr [sin θ + (sin 2θ/n)]
ωr [cos θ + (cos 2θ/n)]
ω²r [sin θ + (sin 2θ/n)]
ω²r [cos θ + (cos 2θ/n)]
The unbalanced primary forces in a reciprocating engine are
Balanced completely
Balanced partially
Balanced by secondary forces
Not balanced
The frictional torque transmitted in a conical pivot bearing with assumption of uniform pressure is __________ as compared to uniform wear.
Less
More
Same
None of these
Higher pairs are those which have
Point or line contact between the two elements when in motion
Surface contact between the two elements when in motion
Elements of pairs not held together mechanically
Two elements that permit relative motion
For high speed engines, the cam follower should move with
Uniform velocity
Simple harmonic motion
Uniform acceleration and retardation
Cycloidal motion
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
When the radius of rotation of balls __________ as the equilibrium speed increases, the governor is said to be unstable.
Remains constant
Decreases
Increases
None of these