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Homework Help: Object in free fall - Velocity

  1. May 8, 2010 #1
    1. The problem statement, all variables and given/known data

    An object is in free fall at the surface of the Earth. In a certain 1.0 second time interval, the average velocity of the object is measured to be 2.0 m/s downward.

    What was the velocity of the object at the beginning of the 1.0 second interval?


    2. Relevant equations

    Vavg = vi + vf / 2

    3. The attempt at a solution

    I came across this as i am studying for my physics final.

    The answer is 2.9 m/s upward.

    I am not sure how to get this because i cannot think of the right equation to use to get me to the correct answer.

    Any help or hints would be greatly appreciated. Thank you
     
  2. jcsd
  3. May 8, 2010 #2

    PhanthomJay

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    Science Advisor
    Homework Helper
    Gold Member

    You have the first equation, with 2 unknowns.
    You need another equation of motion to solve for vi and vf.
    List what is known and unknown.
    Watch your plus and minus signs.
     
  4. May 8, 2010 #3
    It seems to me you need a starting point. The problem as stated seems insoluable--or having infinite solutions, if you prefer.
     
  5. May 8, 2010 #4
    Thank you Jay. I think i got it now using the other equation: vf = vi + at
     
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