Force
Sir Isaac Newton described the motion of all objects using the concepts of inertia and force, and in doing so he found they obey certain conservation laws. In 1687, Newton published his thesis "Philosophiæ Naturalis Principia Mathematica". In this work Newton set out three laws of motion that to this day are the way forces are described in physics.
List of medieval European scientists
Avempace (died 1138), a famous physicist from Muslim Spain who had an important influence on later physicists such as Galileo. He was the first to theorize the concept of a reaction force for every force exerted.