Melc 4

• Aristotle's Notion of Motion Aristotle's ideas on motion focused on the two categories of motion: (1) natural motions, and (2) violent motions
• According to Aristotle, natural motion proceeds from the "nature" of an object.
• Aristotle believed that the world was composed of four elements, and objects were made from the combinations of these elements: air, earth, fire, and water
• Earth being the heaviest, belong to the lowest position. Water is situated above the Earth, followed by air, then fire.
• he also claimed that the motion of the objects depends on the combination of elements comprising the objects
• violent motion. This type of motion is due to either a push or a pull --- this is a forced motion.
• (1) heavier objects fall faster than lighter ones; the speed of an object is proportion to its weigh (2) the speed of fall of a given object depends inversely on the density of the medium it is falling through
• Medium is the required contact force. ✓ Medium flows around object to fill in space left behind. ✓ Result: Object is pushed forward.
• Initial motive force transfers to the medium initially surrounding the object a "power" to act as a motive force. Aristotle's Explanation: ✓ Medium then forces object into new region, which is then imparted with the "power" to act.