On the Admissibility of Given Acceleration-Dependent Forces in Mechanics

In his book “A Treatise on Analytical Dynamics,” Pars asserted that acceleration-dependent forces are inconsistent with one of the fundamental principles of mechanics, namely, with the superposition principle, thus spreading among mechanical scientists the idea that such forces are not admissible in mechanics. This article demonstrates that given forces that depend on acceleration or higher derivatives are admissible in mechanics and shows that this assertion in Pars’s book is fallacious and the only condition for the applicability of such forces is the equation of motion possessing a unique solution.