Re: Newton e Hooke

Luigi Fortunati il 04/02/2025 16:47:15 ha scritto:

There are two inertias: there is the inertia of the body that persists
in its rectilinear and uniform motion and this is not a real force and
there is the inertia of the body that opposes the external force and
this is a real force.

To visualize this *real* inertial force I created the animation
https://www.geogebra.org/m/ddnzbhjy where you see a car that we push
with the black applied force (Fa) that always remains the same even
when we increase the mass of the car with the appropriate slider.

Let's focus on this black force of ours and notice that it acts against
point A of the car.

At this point A, does our force encounter a contrary reaction?

Of course! The car, according to Newton's third law, reacts to our push
with a contrary force applied to the same point A: at point A it
receives the action and at point A it directs its reaction.

And that's the one I drew in blue.

This blue force is inertial, that is, it is an *internal* force that
reacts to compression with compression: the force of the external
action and the opposing internal reaction force compress the area
around point A, on both sides.

And what does point A do? It remains still if the two opposing forces
are equal and opposite but accelerates if the action exceeds the
reaction.

And what is the force that accelerates point A? It is the residual red
"net" force, that is, the resultant of the black and blue forces, on
which it depends.

Luigi Fortunati