section_path: History of the concept/Impetus/John Philoponus
section_name: John Philoponus
paragraph_text: John Philoponus
  
  In about 530 AD, John Philoponus developed a concept of momentum in On Physics, a commentary to Aristotle 's Physics. Aristotle claimed that everything that is moving must be kept moving by something. For example, a thrown ball must be kept moving by motions of the air. Philoponus pointed out the absurdity in Aristotle's claim that motion of an object is promoted by the same air that is resisting its passage. He proposed instead that an impetus was imparted to the object in the act of throwing it.