The two parts are summarized in the following diagram. There are two clauses or parts to this statement - one that predicts the behavior of stationary objects and the other that predicts the behavior of moving objects. Newton's first law of motion is often stated as An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The focus of Lesson 1 is Newton's first law of motion - sometimes referred to as the law of inertia. These three laws have become known as Newton's three laws of motion. Isaac Newton (a 17th century scientist) put forth a variety of laws that explain why objects move (or don't move) as they do. In this unit (Newton's Laws of Motion), the ways in which motion can be explained will be discussed. In a previous chapter of study, the variety of ways by which motion can be described (words, graphs, diagrams, numbers, etc.) was discussed.
