I have question to the Newton III Law and Air Friction. At the free Fall of a Body there is an Air Friction, which is in oppopsite direction to the Gravitation Force. In my opinion the Body pushes to air in Front of it with the Same acceleration as it is accelarated by the Gravitation, so the Force of the Air Friction (Force Air to Body) must have the Same amount as Gravitation but in the opposite direction. But obviously its Not the case. Can somebody explain me, why i am thinking false? Dear greetings
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$\begingroup$ You need to add more detail, such as an example. At the present time, it is difficult to determine exactly what you are asking. $\endgroup$– David WhiteCommented Dec 11, 2023 at 0:34
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$\begingroup$ please read en.wikipedia.org/wiki/Drag_(physics) . the density of the fluid/air enters. $\endgroup$– anna vCommented Dec 11, 2023 at 5:06
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$\begingroup$ In my opinion the Body pushes to air in Front of it with the Same acceleration as it is accelerated by the Gravitation. This is only true for at right at the front of the motion, the vast majority of the air is made to move at an angle to the direction of motion of the body. $\endgroup$– FarcherCommented Dec 11, 2023 at 8:35
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$\begingroup$ Newton III defines. action-reaction pairs. What is the action-reaction pair of forces that you are referring to here? $\endgroup$– Chet MillerCommented Dec 11, 2023 at 13:04
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The paradox in your thinking arises because you are thinking of the reaction of air as if it were a rigid body. Essentially, air can be moved out of the way by the moving body so that the reactive force does not exactly cancel the gravitating force. While the force of gravity remains constant (over acceptable free-fall distances) the force on the object from air is a complicated affair that is a mixture of reactive and frictional forces that depend on a complicated way on the velocity of the object and fluid dynamical properties of air. With the result that the total force on the falling body eventually exactly cancels when the body reaches what is known as the terminal velocity.
answered Dec 11, 2023 at 15:52