Force projection onto body's axis

  1. Hey PhysicsForums. Long time reader looking for some assistance

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

    [​IMG]

    2. The attempt at a solution

    I'm pretty sure the idea is to find the unit position vector to point A, and the force vector F.

    I found the unit position vector to be u = (-4/6)i +(4/6)j + (2/6)k, and the force to be F = (560cos60sin30)i + (560cos60cos30)j + (560sin60)k

    Dotting them together gives me 230 lb, but Mastering Engineering doesn't agree with me. Can anyone point out where I went awry?

    Thanks for reading!
     
  2. jcsd
  3. vela

    vela 12,615
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    The x-component of F should be negative. The rest looks fine to me.
     
  4. Simple mistakes are embarassing :(

    Thank you for your careful eyes!
     
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