The Aristotlean view of the motion of a particle was accepted for 2000 years. It required a change of mindset, scientific method and a rejection of the authority of one of the greatest of Greek philosophers as well as that of the catholic church to a large extent.
Aristotle's view of motion could only survive because scientific experiments were not conducted to prove or disprove physical theories, so that a theory once stated, could be widely propagated and believed if stated often enough by authority figures.
The main points of Aristotlean as opposed to Newtonian motion is summarised in the table.
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Aristotle |
Newton |
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Motion |
A force is required for 'violent' motion, where acceleration is present or the direction of motion changes, but natural motion – air or fire rising, or matter falling – may take place with no force present. |
No force is required for an object to be in motion. |
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Force |
A force causes an object to gain speed. The speed is proportional to the force, so for a body to continue at a constant speed a force is always required. |
A resultant force acting on a body causes the body to accelerate in the direction of that force. The acceleration is proportional to the force. |
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Mass |
Objects of different masses fall at different speeds. |
Objects with difference masses fall with the same acceleration, and if dropped at the same instant will have the same speed or velocity at any instant. |