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Homework Help: Finding average acceleration with two sets of velocity vecotors

  1. Nov 4, 2012 #1
    1. The problem statement, all variables and given/known data
    A jet plane is flying at a constant altitude. At time t1=0 it has components of velocity vx=95m/s, vy=115m/s. At time t2=33s the components are vx=172m/s, vy=35m/s.
    Find average acceleration.

    2. Relevant equations

    avg acceleration=vfinal-vinitial/change in time

    3. The attempt at a solution
    I have no idea if this attempt at the solution makes sense but I took the first set of velocity components and by using the pythagrium theorum found the velocity at t=0. I then did the same thing for t=33. I took the initial velocity number I got and subtracted it from the final velocity number I got and dividied that number by 33. The answer I got was incorrect. I have no idea where to go from here.
  2. jcsd
  3. Nov 4, 2012 #2
    Acceleration is also a vector quantity. What are the components of the acceleration?
  4. Nov 4, 2012 #3
    Since velocity is a vector, you can't necessarily just take the difference between the initial and final vectors directly and come up with the correct answer. With vectors, you can only add them together if they point in the same direction. So in this question, it would be wise to keep the vector components separate while adding/subtracting them. Once you have found the changes in the x and y velocity vectors, you can add them together with the Pythagorean theorem to get the net change in velocity. Make sense? Then you can divide that answer by the change in time.
  5. Nov 4, 2012 #4
    Oh now I understand it. Thank you that really helped!
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