The first principle states that the inertial frame is the one in which
bodies maintain their state of rest.
In my animation
https://www.geogebra.org/m/qdg3kgc8
there is the rigid rod AB which remains at rest and there are the
bodies C and D which move away from their initial position due to the
(real) tidal forces.
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are not
there, it is a inertial reference.
What is the size limit that separates lifts of one type from those of
the other type?
The first principle states that the inertial frame is the one in which
bodies maintain their state of rest.
In my animation
https://www.geogebra.org/m/qdg3kgc8
there is the rigid rod AB which remains at rest and there are the
bodies C and D which move away from their initial position due to the
(real) tidal forces.
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are not
there, it is a inertial reference.
What is the size limit that separates lifts of one type from those of
the other type?
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are notis correct.
there, it is a inertial reference.
[...]
Watch the video
https://www.youtube.com/watch?v=cyPAEMQKBuo
Astronaut Samantha Cristofoletti is on the spaceship in free fall where the gyroscope left free to turn does not remain stationary in its initial position but tilts with respect to the spaceship, ie rotates.
Samantha Cristofoletti explains that it is the spaceship in free fall that rotates and not the gyroscope that maintains its initial position.
Well, if the spaceship rotates, it's not an inertial reference frame.
Luigi Fortunati <fortunati.luigi@gmail.com> wrote:
The first principle states that the inertial frame is the one in which bodies maintain their state of rest.
In my animation
https://www.geogebra.org/m/qdg3kgc8
there is the rigid rod AB which remains at rest and there are the bodies C and D which move away from their initial position due to the (real) tidal forces.
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are not there, it is a inertial reference.
What is the size limit that separates lifts of one type from those of the other type?
Your statement
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are not there, it is a inertial reference.is correct.
However, in practice there are other important facts, notably:
(1) there are almost always tidal forces present, i.e., we almost never
have something that's *exactly* an inertial reference frame (IRF),
and
(2) physics experiments are always of finite accuracy, so we almost
never care about having something that's *exactly* an IRF.
This makes it useful to introduce the concept of "approximate inertial reference frame" (AIRF), where we only require "inertial" to hold up to
some specified error tolerance. And having introduced that concept,
it's then useful to consider Luigi's question for an AIRF.
I.e., it's useful to consider the question "how large can an AIRF be"
(where "size" is measured in both space and time, see below). As we'll
see below, the answer depends on how accurately we want the property "inertial" to hold, i.e., how approximate do we want our AIRF to be.
Jonathan Thornburg [remove -color to reply] il 03/05/2023 08:56:24 ha scritto:
Your statement
Thus, the inertiality of the free-falling elevator is determined by the presence or absence of tidal forces: if tidal forces are there, the free-falling elevator is an accelerated reference, if they are not there, it is a inertial reference.is correct.
However, in practice there are other important facts, notably:
(1) there are almost always tidal forces present, i.e., we almost never
have something that's *exactly* an inertial reference frame (IRF),
and
(2) physics experiments are always of finite accuracy, so we almost
never care about having something that's *exactly* an IRF.
This makes it useful to introduce the concept of "approximate inertial
reference frame" (AIRF), where we only require "inertial" to hold up to
some specified error tolerance. And having introduced that concept,
it's then useful to consider Luigi's question for an AIRF.
I.e., it's useful to consider the question "how large can an AIRF be"
(where "size" is measured in both space and time, see below). As we'll
see below, the answer depends on how accurately we want the property
"inertial" to hold, i.e., how approximate do we want our AIRF to be.
To fully understand everything you wrote, I need to adjust my animation https://www.geogebra.org/m/qdg3kgc8
to introduce the concept of "approximate" inertial frame of reference (AIRF).
My idea is to add one or more sliders so that the user can vary any
dimension at will, enlarging or reducing it to see how the distances
vary (or don't vary) during the approximation of the AIRF towards the infinitely small .
Do I make the dimensions of the lift variable? Or the size of bodies C and D? Or their distance? Or the time?
If you give me these indications, I will modify my animation accordingly.
Luigi Fortunati il 02/05/2023 12:57:39 ha scritto:
Watch the video
https://www.youtube.com/watch?v=cyPAEMQKBuo
Astronaut Samantha Cristofoletti is on the spaceship in free fall where the >> gyroscope left free to turn does not remain stationary in its initial
position but tilts with respect to the spaceship, ie rotates.
Samantha Cristofoletti explains that it is the spaceship in free fall that >> rotates and not the gyroscope that maintains its initial position.
Well, if the spaceship rotates, it's not an inertial reference frame.
I ask you for confirmation.
It seems to me that Samantha's gyroscope works *exactly* like Foucault's pendulum: does it?
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