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Homework Help: Velocity vector homework

  1. Feb 3, 2008 #1
    i have been given that vector r = bt^2i + ct^3j where b and c are positive constants, and i need to know when the velocity vector will make an angle of 45 degrees.

    i have been trying to figure it out and am just confused. i have taken the derivative of vec r, because i know that it becomes velocity but i dont know what to do from there. i cannot figure out the components of what makes up the velocity vector. i feel like i am going in circles. please someone help!!
     
  2. jcsd
  3. Feb 3, 2008 #2

    Doc Al

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    Staff: Mentor

    Hint: When the velocity vector makes an angle of 45 degrees with respect to the horizontal, what can you say about [itex]V_y/V_x[/itex]?
     
  4. Feb 3, 2008 #3
    it will = 1 because the sin and cos of 45 degrees are the same...right?
     
  5. Feb 3, 2008 #4

    Doc Al

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    Staff: Mentor

    Right!
     
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