A Relativistic Dynamics Primer

In early Physics classes the conservation of momentum and conservation of energy are fundmental laws used in all kinds of applications. Momentum is defined as the product of mass and velocity. But it turns out that momentum has to redefined when the velocities involved become relativistic. This new definition has consequences in the concepts that depend on it. This paper Relativistic Dynamics Primer summarizes the basic ideas of momentum and energy when relativistic speeds are in play. In particular, it explains why the formula for momentum used in classical mechanics must be altered to satisfy conservation under a Lorentz transformation and how this change in the definition of momentum leads to the concept of mass as energy in a new formulation of relativistic total energy. The concepts reduce to the familiar Newtonian ones when the velocity is not relativistic. It assumes the reader is familiar with the concepts in the previous blog entry - A Special Relativity Primer. A few examples are worked to apply the concepts discussed.