INERTIA FROM ARISTOTLE TO NEWTON

Inertia, in everyday language, means lack of action, activity, indolence, laziness or something. For this reason, it is customary to associate the inertial rest, which does not exactly correspond to the direction that physics gives the term. The physical meaning of inertia is more comprehensive: inertia is "stay as is," or at rest or in motion. Since ownership of the body of "stay as is" independent of its mass, inertia can be understood as synonymous with mass.



From Aristotle to Descartes: the principle of inertia



According to Aristotle, there is no movement without force. This idea has always been well accepted because it agrees with our everyday observation - if the car engine dies on a level road, he stops. For Aristotle, the motion can be natural when the body seeks its natural place, which explains the falling bodies in the air and the rise of air bubbles in water. When the body moves away from its natural place there, including the horizontal displacement, the movement is violent, and there must be some cause that cause. Only the heavenly bodies can move without cause, with constant speed in perfectly circular paths.



When there is no apparent reason to keep moving, Aristotle proposes ingenious explanations. An arrow, for example, maintains its motion even after leaving the bow because it shifts and splits the air in front; the air then back by pushing the arrow behind. The air resistance, however, and whichever end the arrow drops.



That was one of the ideas of Aristotle's theory less accepted, subject to numerous challenges over time. In the fourteenth century, Father Jean Buridan, French scientist, proposes an alternative and more convincing in explaining the movement of the arrow, introducing the concept of momentum. 0 arc transfers to the arrow a certain momentum, whose intensity depends on the weight and speed of the arrow. It keeps moving until all the momentum is consumed by the air resistance. Otherwise, the arrow would remain indefinitely in movement.



Later Galileo, in his work Dialogues Concerning the Two Chief World Systems, published in 1632, presents arguments that lead to the formulation of the Law of Inertia. Galileo stated quite clearly that in the absence of forces, a moving body must remain indefinitely in motion.



Some years later, René Descartes (1596-1650), French philosopher and mathematician, contemporary of Galileo, the generalized principle of inertia for all bodies, including the heavenly bodies.



Descartes also realized that the rectilinear trajectory is also a consequence of the absence of forces - can have only one body circular motion, for example, if a force oriented towards the center of the circle acts on it. Descartes is best known formulation of the principle of inertia: "A body free from external influences moves with constant speed in a straight line '·..

Newton introduced their three basic laws of mechanics defining the principle of inertia as the tendency of a body subjected to the action of the resultant force equal to zero, remain stationary or uniform rectilinear motion.











# sergiorbtorres



Sincerely,



Prof. Sergio Torres



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