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Calculating final Velocity

  1. Nov 14, 2007 #1
    1. The problem statement, all variables and given/known data

    Find the final velocity of the object if it is initially moving along the x axis with average velocity of -62 m/s.

    Other information
    mass=.462kg
    time=5s
    average force = 0.8N
    impulse=4

    2. Relevant equations

    F=m(Vf-Vi)/t

    3. The attempt at a solution

    I use the equation like this

    (0.8N)=(.426kg)(Vf+62m/s)/(5s)

    =-61.13m/s Is that right?
     
  2. jcsd
  3. Nov 14, 2007 #2
    I dont know why they gave you impulse, you can solve the problem with this equation:

    Vf = Vi + at

    where Vf=final velocity, Vi=initial velocity, a=acc. and t=time.

    Remember - the acc. is .8/.462 because F=ma, so a=F/m.

    Good luck!
     
  4. Nov 14, 2007 #3
    Vf = Vi + at


    Vf= (-62m.s) + (.8/.462)(5)

    = -53.3 m/s

    Thats what I got but it isn't right. I'm sure I didn't up the algebra, did I plug something in wrong?
     
  5. Nov 14, 2007 #4
    well then i guess your initial approach is correct. the equation I gave might not work cuz i didnt read the part that said "avg velocity". I think your -61 is correct
     
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