section_path: History of the concept/Impetus/Peter Olivi, Jean Buridan
section_name: Peter Olivi, Jean Buridan
paragraph_text: Peter Olivi, Jean Buridan
  
  In the 13th and 14th century, Peter Olivi and Jean Buridan read and refined the work of Philoponus, and possibly that of Ibn Sīnā. Buridan, who in about 1350 was made rector of the University of Paris, referred to impetus being proportional to the weight times the speed. Moreover, Buridan's theory was different from his predecessor's in that he did not consider impetus to be self-dissipating, asserting that a body would be arrested by the forces of air resistance and gravity which might be opposing its impetus.