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A time of flight method to measure the speed of sound using a stereo sound card by Carlos C. Carvalho and others by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Online text: arxiv.org/pdf/0712.1577
Publisher: Stanford University (course host; publication publisher not separately stated).
18.303 Linear Partial Differential Equations, Fall 2006 by Matthew J. Hancock by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Basics of Space Flight (2017 edition) by Dave Doody by
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By Dave Doody.
Lunar Laser Ranging Tests of the Equivalence Principle by James G. Williams and others by
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Publication information: arxiv.org/abs/1203.2150
Published in Classical and Quantum Gravity.
Online text: arxiv.org/pdf/1203.2150
Publisher: OpenStax, Rice University.
MIT 8.13–14 Experimental Physics I & II, Junior Lab, Fall 2016–Spring 2017 by MIT Department of Physics by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Electromagnetism lecture notes by Richard Fitzpatrick by
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MIT 2.71 and 2.710 Optics, Spring 2014 by Nicholas X. Fang by
Codex 0 Created 2026-10-13 Updated 2026-11-05
By Nicholas X. Fang.
Publisher: RP Photonics AG.
The entry Wavefronts, www.rp-photonics.com/wavefronts.html , describes surfaces of constant phase, planar and spherical wavefronts, and changes of wavefront shape through optical elements. It provides the geometric context for wavefront curvature.
The Feynman Lectures on Physics, Volume II by Richard Feynman and others by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Publisher: Caltech / The Feynman Lectures Website (online edition).
Additional cited passages: II.14–6, equations (14.37)–(14.38): volume-to-wire conversion; II.14–7, equations (14.39)–(14.43): volume law, displacement convention and cross-product order; II.14–5, equations (14.33)–(14.36): loop magnetic moment and dipole field. Whole-book authors are not separately credited chapter authors; no online-edition publication or revision date was verified.
Additional cited passages: II.13–4, equations (13.12)–(13.13) and subsequent steady-source and closed-circuit discussion; II.13–5, equations (13.17)–(13.18) and internal-current explanation of magnetic matter. Whole-book authors are not separately credited chapter authors; no online-edition publication or revision date was verified.
Additional online chapters: www.feynmanlectures.caltech.edu/II_02.html and www.feynmanlectures.caltech.edu/II_12.html
Additional cited passages: II.2–7, Second derivatives of vector fields, equations (2.52)–(2.54), the Laplacian and the rectangular-component statement after (2.54); II.2–8, Pitfalls, equation (2.60) and final coordinate-system caution. II.12–4, equations (12.19)–(12.22), neutron flux proportional to a scalar diffusion coefficient times the negative density gradient, and local conservation. Equation (12.22) retains the coefficient inside the divergence; reducing it to a constant times the Laplacian requires an additional constancy assumption. Credits remain the existing whole-book authors Richard Feynman, Robert B. Leighton and Matthew Sands; no separate chapter authors or online-edition date are established.
By Eric Murray.
On the Mechanical Equivalent of Heat by James Prescott Joule by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Publisher: The Royal Society.
Cited passages: pp. 64–66 and Plate VII: thermometer calibration, water apparatus and operating sequence; pp. 66, 69–70 and 82: matched controls, apparatus water-equivalent capacity, mechanical corrections and residual losses.
University Physics Volume 2 by Samuel J. Ling and others by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Publisher: OpenStax.
Section15.4, equations15.12–15.13: instantaneous versus average power, relative phase and RMS current/potential-difference conventions.
Waves, phase speed, and group speed (13.012 Hydrodynamics for Ocean Engineers, Laboratory 1) by A. H. Techet by
Codex 0 Created 2026-10-13 Updated 2026-11-05
By A. H. Techet.
Online text: web.mit.edu/13.012/labs_DATA/2003/lab2.pdf
Cited passages: Richard Fitzpatrick, Wave-Front Propagation, 27 June 2014, equations 871–873 and following discussion: no field before t=x/c in the causal dielectric model.
University Physics Volume 1 by William Moebs and others by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Additional section: 14.2 Measuring Pressure.
Cited passages: Gauge Pressure vs. Absolute Pressure, equation 14.11; Manometers, Figure 14.12 and accompanying discussion; Example 14.2, Strategy and Solution, equal pressure at the same height in the same liquid; pressure-unit definition. The citation information credits the whole-book authors and gives publication as 19 September 2016, distinct from any section revision date.
Section15.1, Characteristics of Simple Harmonic Motion, gives the spring restoring force; §5.4 distinguishes mass and gravitational force.
Additional locators: §16.3, uniform-string linear density and wave speed under tension; §16.6, fixed-end standing-wave modes.
Section 10.6, torque vector and perpendicular lever arm. Section 12.3, tensile stress, strain and Young’s modulus: the small-strain axial extension law distinguishes internal deformation from external resultant/moment equivalence.
Thermodynamics and Statistical Mechanics by Richard Fitzpatrick by
Codex 0 Created 2026-10-13 Updated 2026-11-05
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.Figure 3. Visual Studio Code extension installation.Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. - Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact





