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Homework Help: Quadratic Formula examples

  1. Apr 15, 2010 #1

    MacLaddy

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    1. The problem statement, all variables and given/known data

    The Quadratic Equation. I am looking for an example of the quadratic equation being used in any form of engineering, or physics.

    I am supposed to give an example for my algebra class, but I really don't want to do the "two trains left a station," or "sally jumped off a log."

    I don't know if there are ANY applications of this in engineering or physics that I could use, as it needs to be basic algebra, but I am hoping.

    Maybe something simple like [tex]f(w) = 10w^2 + 5x + 25 = 0[/tex], where w is windspeed, and the function is for how many turns an hour a windmill will get... Not sure if something like that exists.

    My class will let me use an existing formula, or to create an example.


    2. Relevant equations

    [tex]ax^2 + bx + c = 0[/tex]

    3. The attempt at a solution

    Searching, googling, pacing, and asking here.

    I appreciate any assistance that can be offered.
     
    Last edited: Apr 15, 2010
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  3. Apr 15, 2010 #2

    LCKurtz

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    How about an artillery shot problem. Given muzzle velocity what elevation angle to hit a target. When will it hit the ground? Uses

    s = (-1/2)gt2+v0t+s0
     
  4. Apr 15, 2010 #3

    MacLaddy

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    I would love to be able to use something like that, but what I mean when I say "basic algebra" is because I honestly can't solve that yet... (sadly) I guess I'll get there soon.

    I know that is pronounced v-naught, but I don't know what it means.

    I appreciate the effort, but perhaps can you give me a simpler explanation? (algebra 101 level)
     
  5. Apr 16, 2010 #4

    LCKurtz

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    Make it simpler. The equation I gave is for a body falling under the influence of gravity. g = 32 ft/sec2, s0 is the initial position, v0 is the initial velocity. You could examine the following proposition:

    Someone claimed that Michael Jordon could jump high enough that he had a 3 second hang time. How high would he have to jump to do that? The equation you need to answer that is

    s = (-1/2)gt2+v0t+s0

    where s is the height at time t. Start the jump with s0 = 0 at time t = 0 and unknown v0. You need some algebra to find the vertex of the (s,t) parabola and relate it to hitting the ground 3 seconds later.
     
    Last edited: Apr 16, 2010
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