Re: Inertia and third principle

Luigi Fortunati il 30/07/2024 19:05:34 ha scritto:

In my animation https://www.geogebra.org/m/qterew9m ...

If body A passes some momentum to body B, body B must politely return 
to body A the *same* momentum it received, no more and no less.
[[Mod. note -- Newton's laws say that (assuming that there are no
external forces acting) the *total* momentum of the system remains
constant.

 
Sure! The *total* momentum of the system remains (undoubtedly)
constant, this is established by the law of conservation of momentum
which I have never disputed.
 

If we look at the momentum *changes* during the collision, we have  
p_A_after - p_A_before = 3.75 - 15 = -11.25 , while B's momentum change
during the collision is   p_B_after - p_B_before = 2.25 - -9 = +11.25
so the momentum *changes* are indeed precisely opposite. -- jt]]

 
Yes, even the *changes* in momentum during the collision are equal and
opposite, otherwise the law of conservation of momentum which I have
never disputed would not be correct.
 
My objection concerns something else, it concerns the equality between
action and reaction (the third principle).

The law of conservation of momentum is equivalent to lawes of inertia
and reaction together. If conseervation of momentum is violated without
interaction the law of inertia is violated. If conservation of momentum
is violated in an interaction the law of reaction is violated.

--
Mikko