What is Aristotle’s law of motion? What are its applications? by Khuram Rafique
Answer by Khuram Rafique:
For Aristotle, there are four objects (i) earth, (ii) water, (iii) air and; (iv) fire.
First two are heavier objects and last two are lighter objects.
Natural tendency for heavier objects is to move downside due to ‘gravity’.
Natural tendency for lighter objects is to move upside due to ‘lavity’.
Law of Motion: Natural tendency for the moving objects is to stop. If motion is to be continued, force is required.
Aristotle knows that objects move in resistant or viscous medium that’s why they eventually stop.
But Aristotle also thinks that objects cannot move in vacuum. For Aristotle, resistant medium is required for the motion to occur.
For example, a projectile is thrown with hand … after the contact of hand is removed then how motion is continued? Aristotle’s answer is that projectile is moving through resistant medium which is air. When it is moving forward, there will be sudden vacuum at the back side of object and then this vacuum will be suddenly filled by the surrounding air. This sudden vacuum filling by the surrounding air will generate a forward thrust and object will be able to move forward even at time when contact of throwing hand is removed.
However the resistance force of resistant medium will eventually overcome the forward thrust and at the end object will stop.
For Aristotle, first of all any motion in vacuum is not possible due to missing thrust. Secondly, if we accept any motion in vacuum then it would lead to absurdities that object will acquire infinite motion due to absence of resistant medium.
So what was absurd in view of Aristotle, that thing was finally shown as natural by Newton.