Richard Livingston il 24/10/2023 18:21:13 ha scritto:
>> In the case of my animation https://www.geogebra.org/m/mjnqb8vk before the collision, the inertia of the mass m1 is not a vector in
>> the reference of m1 but it is certainly a vector in the reference of
>> the mass m2 because it moves horizontally to the right.
>> And the inertia of mass m2 is certainly a vector in the reference of
>> m1 because it moves horizontally to the left.
>> It's correct?

> Inertia is a property of an object, not a dynamic variable. I think
> what you mean is momentum. Momentum is part of a Lorentz invariant
> 4-vector:
>
> p = {energy/c, x-momentum, y-momentum, z-momentum} (in momentum units)
>
> The momentum parts comprise a vector in 3-space. This energy-momentum
> 4-vector is conserved in any collision:
>
> p(m1 before) + p(m2 before) = p(m1 after) + p(m2 after)
>
> This is true even for inelastic collisions as long as the energy lost to
> friction/deformation is included in the the after energy components. This
> is true relativistically provided the relativistically correct energy and
> momenta are calculated.

I know these things, I'm talking about something that isn't in books.

> Inertia is a property of an object...

Yes, that's right, inertia is that property of bodies that makes them go straight at uniform speed.

This is precisely what my question is based on: if inertia is related to rectilinear and uniform velocity, velocity being a vector, inertia should also be a vector.

To me it seemed (and still seems to me) a logical reasoning.

Luigi Fortunati.