1) It took about 2000 years to develop the relationship between force and motion, from Aristotle's observations to Galileo's experiments to Newton's formulation of his laws of motion. 2) Newton defined mass and force and formulated his First Law, which states that 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. 3) Newton's Second Law states that acceleration is directly proportional to net force and inversely proportional to mass, represented by the equation a=Fnet/m. This relationship quantifies how force causes changes in an object's motion.

1. NEWTON’S 1 st & 2 nd Laws of Motion Ch 12-2