Inertial Force: The Unifying Concept

The concept of inertial force is one of the most important and the most difficult in classical dynamics. The complexity and obscurity come from both inertia and force. However, for that very reason, making sense of inertial force may shed light on much of the meaning of mechanics. In fact, inertial force designates a cluster of meanings and touches upon different aspects of science. This will emerge from the history brought here. Different meanings coexist today, thus causing confusion for the novice learner. The challenge and need is to address the concept of inertia and inertial force as the concepts unifying classical physics with the modern physics. Yet, even learned at introductory level, this topic provides benefit to the students through widening the picture of physics as continuously improving itself even in classical mechanics. In fact, without inertial force and the directly related non-inertial observer, classical mechanics cannot treat one of the most important aspects of movement—its relativity. This excursus reviews the development of inertial force as a concept and addresses the way it could be better represented in teaching.