Manuscript submitted to the American Journal of Physics.
A pedagogical framework for analyzing rotating systems under gravity or acceleration. Using a conical pendulum and three fixed camera views, we show how observer geometry determines which physical quantities are operationally detectable.
Key insight: Students see, rather than assume, which aspects of motion survive a given observational geometry—and why no local measurement distinguishes gravity from uniform acceleration.
Differences in what observers measure arise from geometric projection of the same physical motion, not from different underlying dynamics.
This framework makes three things directly visible:
- Mass cancellation — why mass drops out of observable trajectories
- Fictitious forces — what each camera view reveals about non-inertial effects
- Equivalence principle — why gravity and acceleration are locally indistinguishable
| File | Description |
|---|---|
manuscript.tex |
LaTeX source (RevTeX 4.2, PRB preprint format) |
fig_conical_pendulum_projections.png |
Main figure — three camera views |
LICENSE |
CC-BY 4.0 |
pdflatex manuscript.tex
pdflatex manuscript.texNo BibTeX required — bibliography is embedded.
@article{caprazli2025projection,
author = {Caprazli, Kafkas M.},
title = {Observer Geometry and the Operational Detection of Acceleration in Rotating Systems},
journal = {American Journal of Physics},
year = {2025},
doi = {10.5281/zenodo.17918361},
note = {Submitted}
}rotating frames · conical pendulum · equivalence principle · observer dependence · projection geometry · physics education · undergraduate mechanics · non-inertial reference frames · centrifugal force · fictitious forces · classical mechanics · visualization
This work is licensed under CC-BY 4.0.
Kafkas M. Caprazli
Independent Researcher · Wolfsburg, Germany
📧 caprazli@gmail.com
🔗 ORCID 0000-0002-5744-8944