* The role of friction: Aristotle believed that objects naturally sought their "natural place," with heavier objects falling faster and lighter objects rising. He didn't consider the role of friction, which is a force that opposes motion. A feather falls slowly because of air resistance, not because it is inherently "lighter."
* The concept of inertia: Aristotle thought that a force was needed to keep an object in motion. He didn't grasp the concept of inertia, which states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity unless acted upon by an external force.
* The relationship between force and acceleration: Aristotle believed that the speed of an object was directly proportional to the force applied to it. He didn't understand that it's actually the acceleration (the rate of change of velocity) that is proportional to the force. This was later explained by Newton's second law of motion.
In summary, Aristotle's understanding of motion was based on observations of everyday life and lacked the rigorous mathematical framework and experimental testing that later scientists like Galileo and Newton brought to the study of physics.
