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Problem with trigonometry

  1. Oct 14, 2009 #1
    1. The problem statement, all variables and given/known data
    In a certain collision problem the kinematics are determined by the following three equations:

    u=u1cos(@) + SQRT(2) * u2
    u1sin(@)=SQRT(2) * u2
    0.5mu^2=0.5mu1^2 + 0.5(2m)u2^2

    Use the first two equations to express u1 and u2 in terms of u, sin(@) and cos(@). Then substitute in the third equation and obtain solutions for sin(@).

    2. Relevant equations
    see above

    3. The attempt at a solution
    I have that u1=u/(sin(@)+cos(@) and u2=u/(SQRT(2)((cos(@)/sin(@))+1) and substitute those in to the third equation eliminating U and m, but having tried various methods cannot solve the trigonmetry equation. Any help would be greatly appreciated.
    Last edited: Oct 15, 2009
  2. jcsd
  3. Oct 14, 2009 #2


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    This equation is confusing. I can divide both side by u2 and get sin(@)=SQRT(2) which can't be true.
  4. Oct 15, 2009 #3
    Oops sorry, it should be u1sin(@)=SQRT(2)u2
  5. Oct 15, 2009 #4


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    OK. Now tell me what the unknown quantities are and what the known quantities are. In other words, we are solving for what in terms of what?
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