Does a lever/fulcrum reaction demonstrate Newton 3rd Law?

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A lever and fulcrum reaction does not demonstrate Newton's Third Law in the straightforward manner suggested, as multiple force pairs are involved. The discussion emphasizes that Newton's Third Law relates to the conservation of momentum and is applicable in various mechanical contexts. It is noted that solving mechanics problems requires consideration of all three of Newton's laws, not just the third. The complexity of force interactions in a lever system illustrates the necessity of applying multiple principles of physics. Understanding these dynamics is crucial for accurately analyzing mechanical systems.
jimmypantspants
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Say a lever is tilted on a fulcrum with an object on the side in contact with the floor, a mass falls onto the other side, causing the object to go flying. Does this demonstrate Action-reaction ? (action on the lever to action on the object)
 
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No. At least not in the way you seem to imply. There are seversl force pairs involved here.
 
Orodruin said:
No. At least not in the way you seem to imply. There are seversl force pairs involved here.
I agree. N3 refers to conservation of momentum. Third law pairs are present in more than one instance here - but, of course, they are to be found everywhere in mechanics.
I already commented in a recent thread on the same topic that N3 is not the only law that needs to be applied in solving Mechanics problems. Newton stated three laws and he would only have produced one if three were not needed.
 

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