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From: Luigi Fortunati <fortunati.luigi@gmail.com>
Newsgroups: sci.physics.research
Subject: Re: Newton's 3rd law is wrong
Date: Sat, 28 Sep 2024 18:19:13 PDT
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Approved: Jonathan Thornburg [remove -color to reply]" <dr.j.thornburg@gmail-pink.com (sci.physics.research)
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Newton says: If a horse pulls a stone tied to a rope, the horse is also 
pulled equally towards the stone.

It's like tug-of-war: someone pulls the rope to the right, someone else 
pulls it to the left.

The poor rope is at the mercy of whoever pulls more: how do we know who 
pulls more? Let's look at the rope!

If the rope moves at a constant speed, then they both pull with the 
same force.

If the rope accelerates to the right, then the force that pulls to the 
right pulls more and if it accelerates to the left it is the opposite.

No one would ever dream of saying that the opposing forces that pull 
the rope to the right and to the left are always equal and opposite!

Only Newton's law III says so.

By the 3rd law, no one would ever win at tug-of-war!!

Luigi Fortunati

[[Mod. note -- As I explained in a moderator's note on 2024-Sep-16,
you're misunderstanding what Newton's 3rd law says.  Newton's 3rd law
says that
(1) The force the rope applies to the stone is equal in magnitude and
    opposite in direction to the force the stone applies to the rope,
    AND
(2) the force the horse applies to the rope is equal in magnitude and
    opposite in direction to the force the rope applies to the horse.

But Newton's 3rd law does NOT say that (1) = (2).  In fact, if the horse,
rope, and stone are all accelerating to the right, then (2) > (1), with
the difference (which is typically fairly small) being given by
   m_rope * a = (2) - (1)
-- jt]]