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Sliding Friction

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Static Friction

Sliding Friction

Rolling Friction

Fluid Friction

Law of Gravity

Law of Gravity

Centrifugal Force

Centripetal Force

Law of Buoyancy

Law of Buoyancy

Law of Inertia

Law of Acceleration

Law of Action and Reaction | This page is intended for college, high school, or middle school students. For younger students, a simpler explanation of the information on this page is available on theKid's Page. |
The motion of an aircraft through the air can be explained and described by physical principals discovered over 300 years ago by Sir Isaac Newton. Newton worked in many areas of mathematics and physics. He developed the theories ofgravitation in 1666, when he was only 23 years old. Some twenty years later, in 1686, he presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis." The laws are shown above, and the application of these laws to aerodynamics are given on separate slides.Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. If an external force is applied, the velocity will change because of the force.The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines aforce to be equal to change in momentum (mass times velocity) per change in time. Newton also developed the calculus of mathematics, and the "changes" expressed in the second law are most accurately defined in differential forms. (Calculus can also be used to

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