4 ms·

Curved Coordinate Systems and Fictitious Forces

12 points by KqAmJQ7 3y ago

throwaway290 3y ago
I like this article. Should we try to come up with a model in which even more forces are fictitious? Would that exercise reveal something interesting.
- gizmo686 3y ago
  Its also useful to consider a linearly accelerating chordinate. In such a system, you experience a constant force opposite to the acceleration of chooridanate system. That this fictisous force looks just like gravity (for a sufficiently small test particle) leads you directly to the equivelence principle. For practical purposes, fictitious forces are mostly useful because they make working in the corresponding coordinate system easier.
tnecniv 3y ago
I both enjoyed and hate this article. It did provide a chance for me to revisit the fundamental concept of rotating reference frames for the first time in a long time and, given that I know mechanics way better than the last time I thought about this topic, I finally grok the whole fictitious force thing. As the author points out, some of the confusion for me was generated by inconsistent use of terms like “centrifugal” in early physics courses. (Warning: Venting / Rant) However, the article to me epitomizes everything I hate about reading physics literature. Jargon terms are introduced and named as if you should know exactly what that jargon means and never used again, leaving the unfamiliar reader wondering whether or not they are important. Steps of derivations are performed and then only later made clear why they were performed when we get to the result. Notational choices (e.g., the Einstein notation used here) are very inconsistent with those used in most domains for the same mathematical concept. Moreover, while not an issue here since the calculations are fairly simple and the author shows their work, many authors skip most of the steps (often due to journal page / word limits) which leaves you trying to figure out which aspects of the jargon-heavy text are part of the derivation and which are just interesting connections to related work. While every field has plenty of examples of bad technical writing, as someone who knows a good amount of math, no physics papers are always the hardest for me to read and for what always feel like artifacts of the presentation, not due to the difficulty of the technical aspects.

12 points by KqAmJQ7 3y ago

I like this article. Should we try to come up with a model in which even more forces are fictitious? Would that exercise reveal something interesting.

gizmo686 3y ago
Its also useful to consider a linearly accelerating chordinate. In such a system, you experience a constant force opposite to the acceleration of chooridanate system. That this fictisous force looks just like gravity (for a sufficiently small test particle) leads you directly to the equivelence principle. For practical purposes, fictitious forces are mostly useful because they make working in the corresponding coordinate system easier.

tnecniv 3y ago

I both enjoyed and hate this article. It did provide a chance for me to revisit the fundamental concept of rotating reference frames for the first time in a long time and, given that I know mechanics way better than the last time I thought about this topic, I finally grok the whole fictitious force thing. As the author points out, some of the confusion for me was generated by inconsistent use of terms like “centrifugal” in early physics courses. (Warning: Venting / Rant) However, the article to me epitomizes everything I hate about reading physics literature. Jargon terms are introduced and named as if you should know exactly what that jargon means and never used again, leaving the unfamiliar reader wondering whether or not they are important. Steps of derivations are performed and then only later made clear why they were performed when we get to the result. Notational choices (e.g., the Einstein notation used here) are very inconsistent with those used in most domains for the same mathematical concept. Moreover, while not an issue here since the calculations are fairly simple and the author shows their work, many authors skip most of the steps (often due to journal page / word limits) which leaves you trying to figure out which aspects of the jargon-heavy text are part of the derivation and which are just interesting connections to related work. While every field has plenty of examples of bad technical writing, as someone who knows a good amount of math, no physics papers are always the hardest for me to read and for what always feel like artifacts of the presentation, not due to the difficulty of the technical aspects.