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Wind Tunnel - relevant formulae

  1. May 5, 2008 #1
    Hello :)

    I am currently in grade 11, in Australia. I have an assignment to be completed in the wind tunnel, where we could choose any topic we liked. We also needed to write a full report on it.

    My lab partner and I decided to construct a rig for a discus (Sporting implement), and measure the drag and lift generated at angles incrementing by five degrees (0 - 50 degrees).

    We have tabulated our results, but we are having trouble finding a formula that we could use in relation to this. Some other people in the class are looking up the formulas for lift and drag, and their respective coefficients, but I honestly do not feel those formula are necessary, as we do not need to find lift and drag, we need to find the total distance the discus has traveled.

    My initial thought was to just use the formula for projection (Help here would be appreciated), and then, going by the fact that vectors can be added/subtracted, simply do that.

    Does anyone have any ideas, or know of formulas that we could use? as it would be a great help!

  2. jcsd
  3. May 5, 2008 #2


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    Staff: Mentor

    You really do need to start with lift and drag coefficients - otherwise, a discus through is just projectile motion.
  4. May 6, 2008 #3
    Thanks for the reply!

    I understand that without lift and drag, a discus throw is basically a projectile motion, though I'm saying that we have already conducted the wind tunnel experiment in order to find out the lift and drag at certain angles.
    From those results, is it not possible to just add/subtract vectors to find out how far in total the disc has traveled?

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