Timeline for How to affirm whether a frame of reference is Inertial or non-inertial?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Feb 14, 2022 at 5:29 | comment | added | Arc | Your comment really put a question in my mind, so I asked another question, perhaps you might like to see it. | |
| Feb 14, 2022 at 5:00 | comment | added | Arc | Yes, perhaps you are right, the sole source of my confusing thoughts is that I'm trapped in between Newtonian mechanics and general relativity. I always think of classical mechanics in terms of these "new ideas", because geodesics is somehitng that you can calculate in terms of purely classical, non-relativistic classical mechanics. People from navigation systems are used to these kinds of mixed views, where you can speak of proper acceleration and coordinate acceleration, and yet do not speak of GR. | |
| Feb 14, 2022 at 1:26 | comment | added | Claudio Saspinski | @Arc notions like: orbits are inertial movements, or distinction between proper and coordinate acceleration don't have meaning out of GR, with its metrics, covariant derivatives and geodesics. | |
| Feb 13, 2022 at 23:29 | comment | added | Arc | Well, agree, but the 'modern' gravity field understanding of the 19th century still predates GR, right? Newton's strict version of the laws of motion and the law of gravity actually have inconsistencies which have been elucidated along the time, but too many people still take those literally. For instance, too many people still think that any acceleration results in non-inertial movement, and that's something that I think we should try to explain better to all (the distinction between proper acceleration and coordinate acceleration). | |
| Feb 13, 2022 at 23:16 | comment | added | Claudio Saspinski | @Arc I started my answer saying that I am talking about Newton's gravity, not GR. According to Newton, if the force of gravity is balanced by another force, the total force on the object is zero. The concept of field started in the $19^{th}$ century, probably with Faraday. | |
| Feb 13, 2022 at 22:50 | comment | added | Arc | In the case of the orbit around the sun, we don't feel centrifugal forces because gravity is a field force - else we would be completely thorn apart a long ago. Another very distinctive feature of non-inertial rotation is the direction of the rotating body: the person on the merry go round keeps spinning, say facing the center, or facing outwards the rotation, while inertial rotation always face the same orientation in space. Rotation of the planet, or the sun, around its own axis is, of course, non-inertial rotation. | |
| Feb 13, 2022 at 22:47 | comment | added | Arc | This is incorrect. A planet, considering its orbit around the sun, is indeed in an inertial frame of reference. Gravity is a field force, and thus produces no internal compression, the planet simply slides through the field, You can verify this by comparing inertial rotation and non-inertial rotation: a person on a merry go round is subject to a contact force and thus is in a state of non-inertial rotation, the greater the angular velocity, and the greater the radius of rotation, the greater the centrifugal force. | |
| Feb 13, 2022 at 21:13 | history | answered | Claudio Saspinski | CC BY-SA 4.0 |