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Projectile movement with drag

  1. Oct 2, 2008 #1
    Hi, i want to know what are the real effects of air (drag) in the projectile movement and free fall, i mean how drag or air resistance is calculated in both movements, with equations.
  2. jcsd
  3. Oct 2, 2008 #2
    The general differential equation for motion with airdrag is (assuming "high" velocity and fluid at rest):

    m\frac{d \vec v}{d t}=\vec F-\gamma v^2

    Where F is your "usual" forces, gravity etc and [tex]\gamma[/tex] is a factor that depends on the geometry of your body (shape an cross-sectional area) and the density of the fluid:

    \gamma=\frac{\rho_{fl}A C_d}{2}

    You can find more on this term here

    The solution to this equation is that [tex]v\sim\tanh t[/tex] which converges to a constant value as t goes to infinity i. e. there is a terminal velocity.
    Last edited: Oct 2, 2008
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