PHYSICS - Jona Mata Jennifer Kim Physics 3rd Inertia...

Jona Mata & Jennifer Kim
Physics 3 rd
October 17, 2010
Inertia, Momentum and Seatbelts
The principles of Inertia and Momentum are essential aspects and developments
of the study of Physics. While Inertia and Momentum are antithesis of each other, the
principles are alike in the degree of importance to which the latter have achieved in
developing the scientific branch of Physics for the past ages. Inertia and Momentum have
become the focal points for Newton’s First and Second Laws and also have been used for
major branches of Physics, such as Quantum Mechanics. With these essential aspects,
Inertia and Momentum have become important principles that have shaped Physics in its
present form today.
Inertia, by defintion, is the resistance an object has to a change in its state of
motion (MansfieldConnecticut). The history of Inertia arises from the work of Galileo
Galilei in the seventeenth century. Galileo conducted an experiment wherein he recorded
the time of descent of bronze balls of various sizes which rolled down an inclined plane.
With the results stating that the size did not matter and that the speed of descent remained
constant, Galileo concluded that freely falling objects experience uniform acceleration
regardless of mass, as long as extraneous forces, such as air resistance and friction, can be
minimized (HowStuffWorks). French Philosopher, René Descartes, then added to
Galileo’s findings by summarizing in three laws the Cartesian Conservation Principle.
The principle states that each thing, as far as is in its power, always remains in the same
state; and that consequently, when it is once moved, it always continues to move
(Descartes 37). With these prior developments in the study of Inertia, English physicist
Sir Isaac Newton developed his first law of motion.
The first law of motion states that every body remains in a state of rest or uniform
unless it is acted upon by an external unbalanced force. This means that in the absence of