Machine Kinematics Multiple Choice Questions on “Velocity in Mechanisms – 2”.
1. The coriolis component of acceleration exists whenever a point moves along a path that has
a) linear displacement
b) rotational motion
c) gravitational acceleration
d) tangential acceleration
Answer: b
Clarification: When a point on one link is sliding along another rotating link such as in quick return motion mechanism, then Coriolis component of acceleration must be taken into account. It means for Coriolis component, rotational motion is required.
2. In a pantograph, all the pairs are
a) turning pairs
b) sliding pairs
c) spherical pairs
d) self-closed pairs
Answer: a
Clarification: Pantograph is an instrument used to reproduce to an enlarged or a reduced scale and as exactly as possible the path described by a given point. It consists of bars connected by turning pairs.
3. Which of the following mechanism is made up of turning pairs?
a) Scott Russel’s mechanism
b) Peaucellier’s mechanism
c) Hart’s mechanism
d) All of the mentioned
Answer: b and c
Clarification: Exact straight line motion mechanisms are made up of turning pairs. These mechanisms are as follows:
a) Peaucellier’s mechanism
b) Hart’s mechanism.
4. Scott Russel’s mechanism is made up of sliding pair.
a) True
b) False
Answer: a
Clarification: Exact straight line motion mechanisms consists of one sliding pair. The Scott Russell’s mechanism is of this type.
5. An exact straight line motion mechanism is a
a) Scott-Russell’s mechanism
b) Hart’s mechanism
c) Peaucellier’s mechanism
d) All of the mentioned
Answer: d
Clarification: All the mechanisms mentioned above consists of exact straight line motion. Scott-Russell’s mechanism consists of sliding pair whereas Peaucellier’s mechanism and Hart’s mechanism consists of turning pair.
6. Which of the following mechanism is an approximate straight line motion mechanism?
a) Watt’s mechanism
b) Grasshopper mechanism
c) Robert’s mechanism
d) All of the mentioned
Answer: d
Clarification: The mechanism that are approximate straight line motion are as follows:
a) Watt’s mechanism
b) Scott-Russell’s mechanism
c) Grasshopper mechanism
d) Robert’s mechanism
e) Tehebicheff’s mechanism.
7. The fundamental equation for correct steering is
a) sinɸ + sinα = b/c
b) cosɸ – sinα = c/b
c) cotɸ – cotα = c/b
d) tanɸ + cotα = b/c
Answer: c
Clarification: The condition for correct steering is that all the four wheels must turn about the same instantaneous centre.
The fundamental equation for correct steering is
cotɸ – cotα = c/b
where ɸ and α = Angle through which the axix of the outer wheel and inner wheel turns respectively
c = Distance between the pivots of the front axles
b = Wheel base.