What kinematic pair is formed when two moving elements maintain surface contact during operation_________________?
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Answer: D. lower pair
Explanation
Surface contact between moving elements is the defining characteristic of lower kinematic pairs. A sliding or turning action distributes loads across a wide area instead of concentrated points. This broad contact area ensures stability and supports heavy loads during relative operational motion. Kinematic pairs connect machine links to constrain their relative motion into predictable directional paths. Lower pairs include sliding pairs, turning pairs, and screw pairs used in basic machine frames. The area of contact is geometrically identical between the mating surfaces throughout their movement.
Pistons moving inside engine cylinders form classic lower pairs relying on continuous surface contact. Lathe guide ways utilize sliding lower pairs to guide tool carriages with high positional accuracy. Lower pairs are preferred in heavy machinery because surface contact reduces localized contact stresses. Option A is a specific type of lower pair rather than the general category name. Option B represents rolling motion which typically involves line or point contact characteristics. Option C is a distractor term not formally recognized in standard kinematic pair classifications.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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