en Cuevana 3. Physics is a system of models of nature according to which all phenomena are explained in terms of matter and force. Sound confusing? It doesn't have to be! Whether you need help with high school physics, need to review for a college physics class, or you're studying for the AP Physics Exam, this physics tutorial will help you understand the basics, such as Newton's Laws, the Law of Universal Gravitation, Kepler's Law and more.