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Homework Help: Acceleration vs Time Find Velocity

  1. Sep 18, 2007 #1
    1. The problem statement, all variables and given/known data
    The graph shows acceleration versus time of a particle moving along the x axis. Its initial velocity is 8m/s at t=0. What is the particle's velopcity at t=4s?

    http://img259.imageshack.us/img259/6684/graphcc9.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution


    I was thinking of integrating y=-x+4 but I don't think I'm suppose to do that and also I don't know how to find +c.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Sep 18, 2007 #2


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    What does the area under an a-t graph represent?
  4. Sep 19, 2007 #3
    Well integrating the acceleration gets you velocity, does it not?
  5. Sep 19, 2007 #4


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    You don't really want to integrate "y=-x+4"... with those variables.
    When you integrate the function with the appropriate physical variables, what is the physical interpretation of your "c" constant of integration?

    You don't need to actually do the integral [with calculus]... you can do it geometrically using learningphysics' suggestion.
    Last edited: Sep 19, 2007
  6. Sep 19, 2007 #5
    Well the area under the chart is 8 at 4 seconds but that's the vi so how doe sthat come into play?
  7. Sep 19, 2007 #6


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    Try your integration method, as well.
    Now, rethink your answer.
  8. Sep 19, 2007 #7
    correct me if i'm wrong, but i believe the equation v=u+at can be used, since this is a linear graph??

    you know, u(initial velocity), and the product (at) is 0. the initial velocity is equal to the final velocity.
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