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Motion Problem

  1. Dec 13, 2004 #1
    I'm don't know how to do this at all, can anyone help me please?

    If [tex]A=[A\angle\theta_{A}][/tex] and [tex]B=[B\angle\theta_{B}][/tex],

    1) what is the magnitude of A+B?
    2) what is the direction of A+B?
    3) what is the magnitude of 2A+3B?
    4) what is the direction of 2A-3B?
  2. jcsd
  3. Dec 13, 2004 #2

    Doc Al

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    Staff: Mentor

    Start by finding the x and y components of each vector, then operate on those components to find the resultants. You'll need to know that [itex]A_x = A cos\theta_A[/itex] and [itex]A_y = A sin\theta_A[/itex].
  4. Dec 13, 2004 #3
    also keep in mind that once you know the components (x,y,z) of a vector, you can easily calculate the vector's magnitude using the formula sqrt(x²+y²+z²)

    just as an addendum to Doc Al's words

  5. Dec 14, 2004 #4
    This is a new to me, I still couldn't get it. Solve and explain the problem to me Doc? Thank you.
  6. Dec 14, 2004 #5

    Doc Al

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    Staff: Mentor

    Poke around here: http://hyperphysics.phy-astr.gsu.edu/hbase/vect.html#vec2

    I'll do the first one:
    [itex]\vec{R} = \vec{A} + \vec{B}[/itex]
    First the x components:
    [itex]R_x = A_x + B_x = A cos\theta_A + B cos\theta_B[/itex]
    Then the y components:
    [itex]R_y = A_y + B_y = A sin\theta_A + B sin\theta_B[/itex]

    Thus the magnitude of A + B = [itex]\sqrt{(R_x^2 + R_y^2)}[/itex]
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