Description: Learn about Newton's 3 Laws of Motion and how to use each one of them. Newton's 1st Law is an object at rest stays at rest and an object in motion stays in motion with the same speed and direction (velocity) until acted on by an unbalanced force AKA inertia! Newton's 2nd Law is an object's acceleration is directly proportional to the net force applied and inversely proportional to the object's mass. Newton's 3rd Law is for every action, there is an equal and opposite reaction.