Functional purpose: Gears are primarily used to transmit power and rotary motion between shafts (and to convert speed/torque); they do not directly create reciprocating motion. Decide whether the statement “Gears transmit power and rotating or reciprocating motion” is correct.
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AIncorrect
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BCorrect
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COnly rack-and-pinion is reciprocating by design
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DGears are used only for non-powered idling
Answer
Correct Answer: Incorrect
Explanation
Introduction / Context: Gears are toothed machine elements that mesh to transfer power and rotary motion, adjust speed/torque, or change direction between shafts. This item checks whether gears are correctly described as transmitting reciprocating motion as well as rotation.
Given Data / Assumptions:
- Gears mesh with other gears or with racks (linear gear).
- Reciprocating motion means back-and-forth linear motion.
- Other mechanisms (cams, cranks, linkages) convert rotation to reciprocation.
Concept / Approach: A standard gear pair transmits rotation to rotation. Rack-and-pinion converts rotation to linear motion, but the rack travel is not inherently reciprocating unless an external constraint reverses it. True reciprocation with controlled dwell/accelerations is the domain of cams or crank-slider linkages, not ordinary gear trains.
Step-by-Step Solution:1) Identify the input/output forms: rotating shafts for gear pairs.2) Recognize that special cases (rack-and-pinion) deliver linear—not necessarily reciprocating—motion.3) Note that reciprocation usually uses cam followers or crank mechanisms.4) Conclude that the statement claiming gears transmit “reciprocating motion” is inaccurate.
Verification / Alternative check: Design handbooks classify gears under rotary transmission; conversion to reciprocation is cataloged under different mechanism families.
Why Other Options Are Wrong:“Correct”: Overstates gear capabilities.“Rack-and-pinion is reciprocating by design”: It is linear; reciprocation depends on system-level reversal, not the gear element itself.“Only idling”: Gears are fundamental power-transmission components.
Common Pitfalls: Confusing linear with reciprocating; assuming any back-and-forth motion seen in a machine is due to gears rather than cams or crank-sliders.
Final Answer: Incorrect