Aristotles Contribution

Contribution of Aristotle in motion
Aristotle's ideas were believed to be true from 500 BC to 1600 CE. That's about 1,100 years of false knowledge. What Aristotle taught, appeared to be correct because it seemed obvious, but not all things are obvious.

Aristotle's view on motion seems to make sense. Unfortunately, it isn't correct. But because his theories appeared to make sense, they became popular and well accepted for a very long time. The key ideas that Aristotle tried to teach were:
All motion on the Earth is linear .
All motion in the heavens (outer space) is curved .
The speed at which an object falls is directly related to the mass of an object .
Motion could be considered in two main factions: natural and violent.
Motion continues so long as there is only an applied motion to an object. Removing the motion stops the object.
It would take a man named Galileo to start the wheels of change in this field of knowledge called physics.

Galileo, unlike Aristotle, proved that motion to the Earth does not depend on the weight of an object. All objects fall to the ground at the same speed. So you see, the speed at which an object falls at has nothing to do with the mass of the object. All objects that are released from the same starting point reach the ground in the same time. Galileo proved Aristotle wrong. He proved the concept of what is called force and mass.

Isa pang search about Aristotle’s contribution in motion

Dynamics: Motion, And Why Things Move
It is first essential to realize that the world Aristotle saw around him in everyday life was very different indeed from that we see today. Every modern child has since birth seen cars and planes moving around, and soon finds out that these things are not alive, like people and animals. In contrast, most of the motion seen in fourth century Greece was people, animals and birds, all very much alive. This motion all had a purpose, the animal was moving to someplace it would rather be, for some reason, so the motion was directed by the animal’s will. For Aristotle, this motion was therefore fulfilling the “nature” of the animal, just as its natural growth fulfilled the nature of the animal.
To account for motion of things obviously not alive, such as a stone dropped from the hand, he extended the concept of the “nature” of something to inanimate matter. He suggested that the motion of such inanimate objects could be understood by postulating that elements tend to seek their natural place in the order of things, so earth moves downwards most strongly, water flows downwards too, but not so strongly, since a stone will fall through water. In contrast, air moves up (bubbles in water) and fire goes upwards most strongly of all, since it shoots upward through air. This general theory of how elements move has to be elaborated, of course, when applied to real materials, which are mixtures of elements. He would conclude that wood, say, has both earth and air in it, since it does not sink in water.
Natural Motion and Violent Motion
Of course, things also sometimes move because they are pushed. A stone’s natural tendency, if left alone and unsupported, is to fall, but we can lift it, or even throw it through the air. Aristotle termed such forced motion “violent” motion as opposed to natural motion. The term “violent” here connotes that some external force is applied to the body to cause the motion. (Of course, from the modern point of view, gravity is an external force that causes a stone to fall, but even Galileo did not realize that. Before Newton, the falling of a stone was considered natural motion that did not require any outside help.)
(Question: I am walking steadily upstairs carrying a large stone when I stumble and both I and the stone go clattering down the stairs. Is the motion of the stone before the stumble natural or violent? What about the motion of the stone (and myself) after the stumble?) Aristotle’s Laws of Motion
Aristotle was the first to think quantitatively about the speeds involved in these movements. He made two quantitative assertions about how things fall (natural motion): 1. Heavier things fall faster, the speed being proportional to the weight. 2. The speed of fall of a given object depends inversely on the density of the medium it is falling through, so, for example, the same body will fall twice as fast through a medium of half the density.
Notice that these rules have a certain elegance, an appealing quantitative simplicity. And, if you drop a stone and a piece of paper, it’s clear that the heavier thing does fall faster, and a stone falling through water is definitely slowed down by the water, so the rules at first appear plausible. The surprising thing is, in view of Aristotle’s painstaking observations of so many things, he didn’t check out these rules in any serious way. It would not have taken long to find out if half a brick fell at half the speed of a whole brick, for example. Obviously, this was not something he considered important.
From the second assertion above, he concluded that a vacuum cannot exist, because if it did, since it has zero density, all bodies would fall through it at infinite speed which is clearly nonsense.
For violent motion, Aristotle stated that the speed of the moving object was in direct proportion to the applied force.
This means first that if you stop pushing, the object stops moving. This certainly sounds like a reasonable rule for, say, pushing a box of books across a carpet, or a Grecian ox dragging a plough through a field. (This intuitively appealing picture, however, fails to take account of the large frictional force between the box and the carpet. If you put the box on a sled and pushed it across ice, it wouldn’t stop when you stop pushing. Galileo realized the importance of friction in these situations.)
Dynamics: Motion, And Why Things Move
It is first essential to realize that the world Aristotle saw around him in everyday life was very different indeed from that we see today. Every modern child has since birth seen cars and planes moving around, and soon finds out that these things are not alive, like people and animals. In contrast, most of the motion seen in fourth century Greece was people, animals and birds, all very much alive. This motion all had a purpose, the animal was moving to someplace it would rather be, for some reason, so the motion was directed by the animal’s will. For Aristotle, this motion was therefore fulfilling the “nature” of the animal, just as its natural growth fulfilled the nature of the animal.
To account for motion of things obviously not alive, such as a stone dropped from the hand, he extended the concept of the “nature” of something to inanimate matter. He suggested that the motion of such inanimate objects could be understood by postulating that elements tend to seek their natural place in the order of things, so earth moves downwards most strongly, water flows downwards too, but not so strongly, since a stone will fall through water. In contrast, air moves up (bubbles in water) and fire goes upwards most strongly of all, since it shoots upward through air. This general theory of how elements move has to be elaborated, of course, when applied to real materials, which are mixtures of elements. He would conclude that wood, say, has both earth and air in it, since it does not sink in water.
Natural Motion and Violent Motion
Of course, things also sometimes move because they are pushed. A stone’s natural tendency, if left alone and unsupported, is to fall, but we can lift it, or even throw it through the air. Aristotle termed such forced motion “violent” motion as opposed to natural motion. The term “violent” here connotes that some external force is applied to the body to cause the motion. (Of course, from the modern point of view, gravity is an external force that causes a stone to fall, but even Galileo did not realize that. Before Newton, the falling of a stone was considered natural motion that did not require any outside help.)
(Question: I am walking steadily upstairs carrying a large stone when I stumble and both I and the stone go clattering down the stairs. Is the motion of the stone before the stumble natural or violent? What about the motion of the stone (and myself) after the stumble?)