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Homework Help: Force and position problem?

  1. Oct 10, 2011 #1
    1. The problem statement, all variables and given/known data

    The force shown in the figure acts on a 1.7kg- object whose initial speed is 0.44m/s and initial position is x=.27m. Find the speed of the object when it is at the location x=.99m. At what location would the object's speed be 0.32m/s ?



    2. Relevant equations
    I know that W=Fd. K=1/2mv^2. Vf^2=Vi^2+2ad.



    3. The attempt at a solution
    I have no clue where to start. I am completely lost. Where do, or how do I begin? Thanks for the help!
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Oct 10, 2011 #2

    lightgrav

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    Homework Helper

    compute the initial KE, at its initial location.
    That KE is changed by the F.d , as it moves along:
    (.8N)(.23m) extra as it crosses the 0.5m mark. etc.
     
  4. Oct 10, 2011 #3
    Ok, so how does finding the Joules help me solve for velocity and location?
     
  5. Oct 10, 2011 #4

    lightgrav

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    Homework Helper

    the KE contains all the info to find out how fast it's going. (½mv.v)
    it's about KE _at_ a location , just like it used to be "velocity at a time"

    Notice that they ask "where was it going slower than at 0.27m?"
     
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