Talk:Newton's laws of motion

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Figure skaters and 3rd law[edit]

hi, I wonder if the figure skater diagram is optimal? It doesn't indicate any forces: are they holding hands while spinning? are they (about) to push apart? Are there any forces at all involved?

Also, the key 3rd law concept is that of opposite laws: An ideal diagram would show one person pushing the other, and experiencing a force back into their body (the opposite reaction, and also the correct image for a free body diagram... ojryosryun9zeryjzu9tja9*


I removed the following as the conservation of energy article disproves it: Conservation of energy was discovered nearly two centuries after Newton's lifetime, the long delay occurring because of the difficulty in understanding the role of microscopic and invisible forms of energy such as heat and infra-red light.

Newton's 3rd law actually discovered by Leonardo da Vinci[edit]

I can't seem to edit the article... can someone add that Newton's 3rd law was actually discovered by Leonardo da Vinci? Just google 'da vinci 3rd law' for a bunch of sources

Action and reaction with velocity[edit]

Newton's original Latin reads:

Hisce volui tantum ostendere quam late pateat, quamq; certa sit Lex tertia motus. Nam si aestimetur Agentis actio ex ejus vi et velocitate conjunctim; et Resistentis reactio ex ejus partium singularum velocitatibus et viribus resistendi ab earum attritione, cohaesione, pondere et acceleratione oriundis; erunt actio et reactio, in omni instrumentorum usu, sibi invicem semper aequales. Et quatenus actio propagatur per instrumentum et ultimo imprimitur in corpus omne resistens, ejus ultima determinatio determinationi reactionis semper erit contraria.

from Philosophiae Naturalis Principia Mathematica, Axiomata, sive Leges Motus, P.24,_sive_Leges_Motus

Translated to English, this reads:

I was only willing to show by those examples the great extent and certainty of the third Law of motion. For if we estimate the action of the agent from its force and velocity conjunctly, and likewise the reaction of the impediment conjunctly from the velocities of its several parts, and from the forces of resistance arising from the attrition, cohesion, weight, and acceleration of those parts, the action and reaction in the use of all sorts of machines will be found always equal to one another. And so far as the action is propagated by the intervening instruments, and at last impressed upon the resisting body, the ultimate determination of the action will be always contrary to the determination of the reaction.

from The Mathematical Principles of Natural Philosophy, Axioms or Laws of Motion, P.24,_or_Laws_of_Motion

F1v1 = -F2v2