# Machine Kinematics Questions and Answers – Forces Acting in a Mechanism

This set of Machine Kinematics Multiple Choice Questions & Answers (MCQs) focuses on “Forces Acting in a Mechanism”.

1. Coriolis component of acceleration is a component of translatory acceleration.
a) True
b) False

Explanation: Its unit is m/s2. Therefore translatory acceleration (at = 2ωV).

2. 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.
a) True
b) False

Explanation: It does exists at infinity distance. Kennedy theorem says number of instantaneous center N = n(n – 1)/2

3. 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
a) 40п2 cm/s2
b) 0.4пcm/s2
c) 40пcm/s2
d) 4пcm/s2

Explanation: Coriolis acceleration = 2ωV = 2 x 2пN/60 x V = 2 x 2п x 60/60 x 10 = 40пcm/s2

4. A body in motion will be subjected to coriolis acceleration when that body is
a) in plane rotation with variable velocity
b) in plane translation with variable velocity
c) in plane motion which is a resultant of plane translation and rotation
d) 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.

5. Mechanism used to produce a diagram to an enlarged or reduced sacle
a) hart’s mechanism
b) pantograph
c) grasshopper mechanism
d) peaucellier’s mechanism

Explanation: Pantograph mechanism is used to produce a diagram to an enlarged or reduced sacle.
Hart’s mechanism is used to produce exact straight line motion mechanism.
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6. A straight line mechanism made up of turning pairs
a) hart’s mechanism
b) pantograph
c) grasshopper mechanism
d) none of the mentioned

Explanation: Exact straight line motion mechanisms made up of turning pairs are peaucellier’s mechanism and hart’s mechanism.

7. Approximate straight line motion consisting of one sliding pair
a) hart’s mechanism
b) pantograph
c) grasshopper mechanism
d) peaucellier’s mechanism

Explanation: Hart’s mechanism is used to produce exact straight line motion mechanism.
Grasshopper mechanism gives approximate straight line motion consisting of one sliding pair.

8. Exact straight line motion mechanism
a) hart’s mechanism
b) pantograph
c) grasshopper mechanism
d) none of the mentioned

Explanation: Exact straight line motion mechanisms made up of turning pairs are peaucellier’s mechanism and hart’s mechanism.

9. The sense of Coriolis component 2ωV is the same as that of the relative velocity vector V rotated.
a) 450 in the direction of rotation of the link containing the path
b) 450 in the direction opposite to the rotation of the link containing the path
c) 900 in the direction of rotation of the link containing the path
d) 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.
The direction of coriolis component is along a line rotated 900 from the sliding velocity in a direction same as that of the angular velocity of the slotted lever.

10. What is the direction of the coriolis component of acceleration in a slotted lever-crank mechanism?
a) Along the sliding velocity vector
b) Along the direction of the crank
c) Along a line rotated 900 from the sliding velocity vector in a direction opposite to the angular velocity of the slotted lever
d) 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.
The direction of coriolis component is along a line rotated 900 from the sliding velocity in a direction same as that of the angular velocity of the slotted lever.

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