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Acceleration in Two Dimensions

  1. Jan 29, 2012 #1
    1. The problem statement, all variables and given/known data
    A watercraft with an initial velocity of 6.4 m/s [E] undergoes an average acceleration of 2.0 m/s2 for 2.5 s. What is the final velocity of the watercraft?


    2. Relevant equations
    vf = vi + a * t
    a = v / t
    v = v2 + (-v1)
    pythagoras and cosine law?

    3. The attempt at a solution

    I think I need to separate the velocities into x and y components and calculate the final velocity in both the x and y components to find the final velocity, but I don't know if that's correct. To be honest I don't really know where how to start the question.
     
    Last edited: Jan 29, 2012
  2. jcsd
  3. Jan 29, 2012 #2

    BruceW

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    Yep, that's how you should do it. You've got the x acceleration and y acceleration, and so you can solve the equations of motion for each coordinate separately.
     
  4. Jan 29, 2012 #3
    But I don't think I have enough known variables to do that. If I use vfx = vix + ax * t then I don't have ax and I don't have the initial velocity in the y direction either so I can't figure out the final velocity in the y direction.
     
  5. Jan 29, 2012 #4

    BruceW

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    Yes, you do have ax, because the question says that the acceleration is only in the south direction.
    And you do know the initial velocity in the y direction, because the question says that the initial velocity is purely to the east.
     
  6. Jan 29, 2012 #5
    So they are both 0 then? I think that clears up a lot of my confusion with this problem.
     
  7. Jan 30, 2012 #6

    BruceW

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    Yep. that's right
     
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