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Object thrown

  1. Jan 6, 2013 #1
    I am trying to work out the problem for t in the equation. h=vt-1/2gt^2. I have the given for h,v, and g. How do I get everything except t on one side of the equation to solve for t.
  2. jcsd
  3. Jan 6, 2013 #2
    You learned this in Algebra II. (Substitute x for t).
  4. Jan 6, 2013 #3
    Think back to algebra, that is where you should have learned to solve for "t" when you have "t" to the second power and first power. The buzz word for what you have there is a "quadratic equation"
  5. Jan 6, 2013 #4


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    Note that one has terms of 1, t, t2, which tells one that this is a quadratic equation, so one can solve for the roots of the quadratic equation.

    Remember, for ax2 + bx + c = 0, there are two unqiue solutions. However, in physics, one would be the proper solution, for example, the one for which t is positive.

    There would be a lot of manipulation to get t or x on one side, and the answers on the other side, but it is doable.
  6. Jan 6, 2013 #5
    I ended up with t=(v-sqrt(v2-2*g*h)/g to get the answer I needed for the given info h=100,g=9.81, and v=50. Thanks
  7. Jan 6, 2013 #6
    wrong v2 is actually v^2
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