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Homework Help: Air resistance calculations

  1. Nov 22, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm trying to find the acceleration due to air resistance in x direction and acceleration due to air resistance +gravity in y component.

    given variables
    angle= 45 degrees

    Basically, I have to program a projectile motion program accounting air resistance, but my biggest problem physics wise is my huge ax, and y acceleration, which prevent my program to loop even more:/

    2. Relevant equations
    ax= fairx/mass = -cdVix^2/mass
    ay= fairy+fg

    3. The attempt at a solution

    fairx= (0.4)(20cos45)^2=80N
    ax= 80n/0.14263kg = 560.498844m/s^2
    ay = well....its in the thousands >.>

    does this mean i have to assume f=Cd*V instead of being proportional to V^2?
    Last edited: Nov 22, 2009
  2. jcsd
  3. Nov 22, 2009 #2


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    Science Advisor
    Homework Helper

    Hi hallowon! :smile:
    No, that can't be right …

    a is L/T2, and the RHS is L2/T2 :confused:

    you need an extra factor with dimensions 1/length (or area/volume).

    Maybe this will help … http://en.wikipedia.org/wiki/Drag_coefficient" [Broken]
    Last edited by a moderator: May 4, 2017
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