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Homework Help: Work Done On A Slingshot

  1. Mar 19, 2015 #1
    1. The problem statement, all variables and given/known data

    yo5tzZ8.png
    2. Relevant equations

    The given elastic force equation

    3. The attempt at a solution

    I plugged in the numbers, with 0.2m for the change in s and 45 for a. Since I knew that work was equal to force * distance, I multiplied that result by another 0.2m. This got me 0.0144J, or 14.4mJ. Since I knew that the slingshot was stretching in the direction you pull, the work had to be positive.

    Unfortunately, my answer is incorrect. :(
     
  2. jcsd
  3. Mar 20, 2015 #2
    Don't forget that work is the INTEGRAL of F dot dL, not just straight multiplication!
     
  4. Mar 20, 2015 #3

    ehild

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    Homework Helper

    The force is not constant, the work can not be calculated by multiplying maximal displacement with maximal force.
     
  5. Mar 21, 2015 #4
    Thanks guys! Seems really obvious now that I remember it.
     
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