May 2018 Issue, Volume 86, No. 5
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
Papers
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); https://doi.org/10.1119/1.5029919
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