Evaluating Jacob Bernoulli's Ship Propulsion Artifice: Euler's Analysis and Critique

Abstract

The present work examines and compares the approaches of Jacob Bernoulli and Leonhard Euler to the problem of ship propulsion generated by internal forces. Jacob Bernoulli's analysis, developed in the late 17th century, relies on geometric interpretations and algebraic relationships to estimate the impulse exerted by a pendulum within a ship. His results, however, are shown to overestimate the force by scaling it with the height of fall rather than the velocity at the end of the fall and by amplifying it with a time dependence factor that proves to be erroneous. Euler's subsequent analysis, conducted nearly 50 years later, provides a more rigorous and mechanically sound treatment of the problem. Utilizing differential equations and a deeper understanding of the principles of motion, Euler demonstrates that no net motion can be generated by internal forces alone, thus refuting the concept of perpetual motion as proposed by Jacob Bernoulli. By comparing the two methodologies, this work highlights the evolution of mathematical and physical analysis from the intuitive but flawed approaches of the early calculus pioneers to the more precise and reliable methods established by later mathematicians. Euler's work not only corrects the errors in Jacob Bernoulli's analysis but also solidifies the understanding that propulsion requires external forces, a conclusion consistent with the laws of Newtonian mechanics.