May 2018 Issue, Volume 86, No. 5May 2018 issue of the American Journal of Physics


The flight of Newton's cannonball

Newton's Cannon is a thought experiment used to motivate orbital motion. Cannonballs were fired from a high mountain at increasing muzzle velocity until they orbit the Earth. We will use the trajectories of these cannonballs to describe the shape of orbital tunnels that allow a cannonball fired from a high mountain to pass through the Earth. A sphere of constant density is used as the model of the Earth to take advantage of the analytic solutions for the interior trajectories that exist for that model. For the example shown, the cannonball trajectories that pass through the Earth intersect near the antipodal point of the cannon.


Letters to the Editor

Comment on “Decluttering our thinking with the life-changing magic of twiddle” [Am. J. Phys. 86, 143–145 (2018)] by Rod Cross. DOI: 10.1119/1.5029825

Response to “Comment on ‘Decluttering our thinking with the life-changing magic of twiddle’” [Am. J. Phys. 86, 325 (2018)] by Sanjoy Mahajan. DOI: 10.1119/1.5029828


Exploring extra dimensions with scalar fields by Katherine Brown, Harsh Mathur, and Mike Verostek. DOI: 10.1119/1.5024221

The flight of Newton's cannonball by W. Dean Pesnell. DOI: 10.1119/1.5027489

Reversible and irreversible heat engine and refrigerator cycles by Harvey S. Leff. DOI: 10.1119/1.5020985

Relativistic jets: An astrophysical laboratory for the Doppler effect by Nadia L. Zakamska. DOI: 10.1119/1.5022796

Building an adiabatic quantum computer simulation in the classroom by Javier Rodríguez-Laguna, and Silvia N. Santalla. DOI: 10.1119/1.5021360

Back of the Envelope

A quantity without its units is like water without wetness by Sanjoy Mahajan. DOI: 10.1119/1.5030542

Physics Education Research

Quantitative critical thinking: Student activities using Bayesian updating by Aaron R. Warren. DOI: 10.1119/1.5012750

Apparatus and Demonstration Notes

Gamma ray spectroscopy with Arduino UNO by C. M. Lavelle. DOI: 10.1119/1.5026595

Book Reviews

The Lazy Universe: An Introduction to the Principle of Least Action by C. G. Gray. DOI: 10.1119/1.5024210

Classical Field Theory by David Boozer. DOI: 10.1119/1.5030552

Books Received

American Journal of Physics 86, 400 (2018);

About AJP

General Information, Resources for Authors, Reviewers, and Readers

Additional Resources