Aristotlean-and-Galilean-Theory-of-Motion.pptx
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Aristotelian and Galilean Concept of Motion Learning Objectives At the end of this lesson, students should be able to: Explain Aristotle’s conceptions of motion (vertical motion, horizontal motion, and projectile motion) Explain how Galileo inferred that objects in vacuum fall with uniform accelerat...
Aristotelian and Galilean Concept of Motion Learning Objectives At the end of this lesson, students should be able to: Explain Aristotle’s conceptions of motion (vertical motion, horizontal motion, and projectile motion) Explain how Galileo inferred that objects in vacuum fall with uniform acceleration, and that force is not necessary to sustain horizontal motion Aristotle’s Views on Motion Aristotle’s view on motion was based on his observations which made his ideas acceptable and stood for many years. According to Aristotle, motion can either be natural motion or a violent motion. Natural Motion Based on Aristotle, occurs when an object moves and returns to its natural state depending on the composition that object is made of. Natural Motion An object made of material similar to earth will return to earth or an object that is similar to air will return to the air. Natural Motion According to Aristotle, smoke goes up in the atmosphere because it resembles the air. Natural Motion A rock mostly resembles the earth so when it is thrown upward its natural tendency is to go back to Earth, its natural state. Violent Motion Violent motion occurs when an object moves after an external force, such as pushing or pulling, is applied to it. No motion will take place unless there is a ‘mover’ in contact with an object. Violent Motion Violent motion based on Aristotle’s idea only occurs when an object is being pushed or pulled. Vertical Motion Aristotle believed that the vertical motion of an object depends on the kind of element that made up the object. Vertical Motion When a rock was thrown upward, it would fall to the ground. Vertical Motion Objects made up of water would tend to move in a region immediately above the ground. Vertical Motion Objects made up of air would tend to rise because the atmosphere was their natural resting place Vertical Motion Objects made up of fire would tend to move upward, just above the atmosphere Vertical Motion Aristotle also explained that an becomes heavier when it contains amounts of earth elements. He also that heavier objects would fall faster ground than lighter objects. object large added to the Horizontal Motion Aristotle explained that horizontal motion is caused by force. This force is what Aristotle referred to as the impetus. Horizontal Motion According to Aristotle, an arrow moves forward as soon as it is released from the bow because of the air resistance pushing it. Projectile Motion Aristotle also tried to explain projectile motion. He believed that projectiles moved parallel to the ground until it was the object’s time to fall toward the ground. Projectile Motion The path of the motion of a projectile based on Aristotle’s idea. Check Your Understanding Identify whether the following scenarios show natural, violent, or projectile motion as perceived by Aristotle. 1. A paper falls on the ground. Check Your Understanding Identify whether the following scenarios show natural, violent, or projectile motion as perceived by Aristotle. 2. The soccer player kicks the ball to the goal. Check Your Understanding Identify whether the following scenarios show natural, violent, or projectile motion as perceived by Aristotle. 3. A glass of water was spilled on the table. Check Your Understanding Identify whether the following scenarios show natural, violent, or projectile motion as perceived by Aristotle. 4. The police officer fires a gun. Its bullet falls on the roof of a house nearby. Check Your Understanding Identify whether the following scenarios show natural, violent, or projectile motion as perceived by Aristotle. 5. Water vapor coming out of a kettle with boiling water. Galileo’s Views of Motion During the 1500s, an Italian scientist named Galileo Galilei challenged Aristotle’s concepts of motion. Galileo, through actual and thorough experiments, disagreed with Aristotle and provided his own description of motion. Vertical Motion Galileo believed that the vertical motion of objects was downward due to gravity. Unlike Aristotle, he believed that objects fall at the same rate even if they have different weights considering that air resistance is ignored. Vertical Motion According to Galileo, a 1-kg object will fall on the ground at the same instant as the 10-kg object provided that they are dropped at the same height. Horizontal Motion Galileo explained horizontal motion in such a way that an object in motion, if unimpeded, will continue to be in motion. He noted that an external force is not necessary to maintain horizontal motion. Horizontal Motion Most of Galileo’s ideas came from his “thought experiments”. These were done only by thinking about the situation in the experiment and analyzing the possible outcomes, so no actual experimentations were done. Horizontal Motion Based on Galileo’s concept of motion, if an object is pushed on a flat and frictionless surface, the object will continue moving and its motion will be unimpeded. Horizontal Motion The movement of the ball on a rough surface is affected by the friction on the surface making the ball slow down and stop. Projectile Motion Galileo described the projectile motion as the combination of horizontal and vertical motions. He referred to this combination of motions as compound motion. Projectile Motion Contrary to Aristotle’s view, Galileo believed that projectiles follow a curved trajectory. He explained that a cannonball launched into the air would move in a curve rather than fall abruptly to the ground. Projectile Motion The comparison between Aristotle’s and Galileo’s path of a cannonball under projectile motion. Check Your Understanding Determine whether the statement is true or false. 1. Compound motion is the same as horizontal motion. Check Your Understanding Determine whether the statement is true or false. 2. According to Galileo, a heavy object thrown in the sea will sink because its weight is less than the force acted on it by the water. Check Your Understanding Determine whether the statement is true or false. 3. Vertical motion is highly influenced by gravity. Check Your Understanding Determine whether the statement is true or false. 4. In nature, an object in horizontal motion will definitely stop moving at a certain point and time. Check Your Understanding Determine whether the statement is true or false. 5. According to Galileo, the speed of a falling object depends on its weight. Galileo’s Inclined Plane Experiment Galileo was fascinated by the behavior of falling objects. He wondered if two objects of different mass were dropped at the same height, which will hit the ground first? Galileo’s Inclined Plane Experiment Based on his observations, Galileo knew that falling objects increase their speed as they go down. This change in speed per unit time is called acceleration. He postulated that objects fall with uniform acceleration. Galileo’s Inclined Plane Experiment Even without equipment to measure the change in speed of falling objects, Galileo was able to investigate acceleration through inclined planes by his thought experiments. Galileo’s Inclined Plane Experiment He used a ball on an inclined plane with a small slope so that the ball accelerated more slowly than an object in free fall. His experimental design allowed him to determine the relationship between the time and the distance traveled by an object. Galileo’s Inclined Plane Experiment Galileo’s Inclined Plane Experiment Observation 1. The velocity of the ball increased as the ball move down the incline. Galileo’s Inclined Plane Experiment Observation 2. The total distance traveled by the ball depended on the square of the time. Galileo’s Inclined Plane Experiment Observation 3. As the inclined plane became steeper, the acceleration of the rolling ball increased Galileo’s Inclined Plane Experiment Observation 4. The ball reached its maximum acceleration when the inclined plane was positioned vertically as if it was simply falling
