Machine Kinematics

Forces Acting in a Mechanism

Question 1
Marks : +2 | -2
Pass Ratio : 100%
Exact straight line motion mechanism
hart’s mechanism
pantograph
grasshopper mechanism
none of the mentioned
Explanation:
Exact straight line motion mechanisms made up of turning pairs are peaucellier’s mechanism and hart’s mechanism.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
Coriolis component of acceleration is a component of translatory acceleration.
True
False
Explanation:
Its unit is m/s2. Therefore translatory acceleration (at = 2ωV).
Question 3
Marks : +2 | -2
Pass Ratio : 100%
Approximate straight line motion consisting of one sliding pair
hart’s mechanism
pantograph
grasshopper mechanism
peaucellier’s mechanism
Explanation:
Hart’s mechanism is used to produce exact straight line motion mechanism.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
What is the direction of the coriolis component of acceleration in a slotted lever-crank mechanism?
Along the sliding velocity vector
Along the direction of the crank
Along a line rotated 900 from the sliding velocity vector in a direction opposite to the angular velocity of the slotted lever
Along a line rotated 900 from the sliding velocity in a direction same as that of the angular velocity of the slotted lever.
Explanation:
The sense of Coriolis component 2ωV is the same as that of the relative velocity vector V rotated 900 in the direction of rotation of the link containing the path.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
A body in motion will be subjected to coriolis acceleration when that body is
in plane rotation with variable velocity
in plane translation with variable velocity
in plane motion which is a resultant of plane translation and rotation
restrained to rotate while sliding over another body
Explanation:
When a point on one link is sliding along another rotating link, such as in quick return motion mechanism, then the coriolis component of the acceleration must be calculated.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
Mechanism used to produce a diagram to an enlarged or reduced sacle
hart’s mechanism
pantograph
grasshopper mechanism
peaucellier’s mechanism
Explanation:
Pantograph mechanism is used to produce a diagram to an enlarged or reduced sacle.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
If the relative motion between two links of a mechanism is pure sliding, then the relative instantaneous center for these two links does not exist.
True
False
Explanation:
It does exists at infinity distance. Kennedy theorem says number of instantaneous center N = n(n – 1)/2
Question 8
Marks : +2 | -2
Pass Ratio : 100%
A straight line mechanism made up of turning pairs
hart’s mechanism
pantograph
grasshopper mechanism
none of the mentioned
Explanation:
Exact straight line motion mechanisms made up of turning pairs are peaucellier’s mechanism and hart’s mechanism.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
The sense of Coriolis component 2ωV is the same as that of the relative velocity vector V rotated.
450 in the direction of rotation of the link containing the path
450 in the direction opposite to the rotation of the link containing the path
900 in the direction of rotation of the link containing the path
1800 in the direction opposite to the rotation of the link containing the path
Explanation:
The sense of Coriolis component 2ωV is the same as that of the relative velocity vector V rotated 900 in the direction of rotation of the link containing the path.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
A slider sliding at 10 cm/s on a link which is rotating at 60 r.p.m. is subjected to Coriolis acceleration of magnitude
40п2 cm/s2
0.4пcm/s2
40пcm/s2
4пcm/s2
Explanation:
Coriolis acceleration = 2ωV = 2 x 2пN/60 x V = 2 x 2п x 60/60 x 10 = 40пcm/s2