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Homework Help: Velocity as a function of force/impulse/time.

  1. Mar 2, 2008 #1
    1. The problem statement, all variables and given/known data

    The force shown in the force vs time diagram in Figure P6.11 acts on a 1.5 kg object. Find the impulse of the force, the final velocity of the object if it is initially at rest, and the final velocity if initial velocity is -2.00 m/s.

    http://books.google.com/books?id=wD...x_cOMU0&sig=cqAzhugYbnZdpBwdwDdlRM82s1g&hl=en

    2. Relevant equations

    V[tex]^{2}[/tex] = V[tex]_{0}[/tex][tex]^{2}[/tex] + 2a[tex]\Delta[/tex]x

    3. The attempt at a solution

    I know impulse is just 8 newton seconds, and i know that's the right answer. But the 2nd question is getting me.

    V[tex]^{2}[/tex] = 0 + 2(2/1.5)(5) gives V[tex]^{2}[/tex] = 13.33. so v = 3.65.

    But the answer is v = 5.3.

    Where did I go wrong?
     
  2. jcsd
  3. Mar 2, 2008 #2

    Shooting Star

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    Homework Helper

    This is when accn is const, which here it's not.

    Use impulse = change in momentum.
     
  4. Mar 2, 2008 #3

    Astronuc

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    Staff Emeritus
    Science Advisor

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