Machine Kinematics Question Paper on “Exact Straight Line Motion Consisting of One Sliding Pair”.
1. Which of the following is an exact straight line mechanism?
a) Scott Russell’s mechanism
b) Watt’s mechanism
c) Grasshopper mechanism
d) Robert’s mechanism
Answer: a
Clarification: Scott Russell’s mechanism is an exact straight line mechanism, however this mechanism is not so useful for practical purposes as friction and wear of sliding pair is more than that of turning pair.
2. Scott Russell’s mechanism is very important for practical purposes.
a) True
b) False
Answer: b
Clarification: Scott Russell’s mechanism is not so useful for practical purposes as friction and wear of sliding pair is more than that of turning pair.
3. Which of the following mechanisms is an approximate straight line mechanism?
a) Scott Russell’s mechanism
b) Watt’s mechanism
c) Gnome engine
d) Oscillating engine
Answer: b
Clarification: Watt’s mechanism is an approximate straight line mechanism. It is a crossed four bar chain mechanism used in early steam engines.
4. Which of the following mechanism forms an elliptical trammel?
a) Modified Scott Russell’s mechanism
b) Watt’s mechanism
c) Gnome engine
d) Oscillating engine
Answer: a
Clarification: Modified Scott Russell’s mechanism is similar to Scott russell’s mechanism but in this case the path traced by an arbitrary point P on the link is an ellipse.
5. Which of the following mechanisms has the form of trapezium in its mean position?
a) Scott Russell’s mechanism
b) Watt’s mechanism
c) Grasshopper mechanism
d) Robert’s mechanism
Answer: d
Clarification: Robert’s mechanism is a four bar chain mechanism, which, in its mean position, has the form of a trapezium.
6. Which of the following mechanisms was used in early days to give long stroke with a very short crank?
a) Scott Russell’s mechanism
b) Watt’s mechanism
c) Grasshopper mechanism
d) Robert’s mechanism
Answer: c
Clarification: The Grasshopper mechanism was used in early days as an engine mechanism which gave long stroke with a very short crank.
7. In Scott Russell’s mechanism the straight line motion is generated.
a) True
b) False
Answer: b
Clarification: In Scott Russell’s mechanism, straight line motion is not generated but merely copied and this mechanism is not much of practical value due to wear and friction in sliding pair.
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