Date: Dec 20, 2012 5:55 PM
Author: Louis Talman
Subject: Re: Physics problem --ball rolling down an inclined plane

On Thu, 20 Dec 2012 14:32:50 -0700, Peter Duveen <> wrote:

> High school physics students are taught so-called Newtonian mechanics,
> but cannot solve the simple problem of a ball rolling down an inclined
> plane. Rigid bodies are outside the purview of Newtonian mechanics, as
> Newton himself seems to have admitted in The Principia. However, the
> application of D'Alembert's Principle yields a solution to this simple
> problem. The problem becomes particularly simple when worked out for a
> thin cylinder or ring rolling down an inclined plane. Should high school
> students be introduced to D'Alembert's Principle?

Have they been introduced to moments of inertia? That's a topic that's
mostly beyond the high school level because one must be able to set up a
multi-dimensional integral to compute them.

Even then, I'd think that Conservation of Energy might give an easier

- --Lou Talman
Department of Mathematical & Computer Sciences
Metropolitan State University of Denver