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Homework Help: What is the common velocity of the arrow

  1. Mar 8, 2009 #1
    1. The problem statement, all variables and given/known data

    An arrow of mass 100 g is fired with an initial horizontal velocity of 40 m s–1 to the right at an apple of mass 80 g that is initially at rest on a horizontal surface. When the arrow strikes the apple, the two objects stick together. What is the common velocity of the arrow and apple after the impact?

    2. Relevant equations
    Momentum = mass * velocity


    3. The attempt at a solution

    Initial Momentum of the Arrow
    p=m*v
    =(.1)(40)
    = 4

    4=.08* v
    therefore v= 50 m/s

    the answer says it's 22m/s
     
  2. jcsd
  3. Mar 9, 2009 #2

    rl.bhat

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    Homework Helper

    Re: Momentum

    4=.08* v
    therefore v= 50 m/s

    This is wrong.
    When the arrow strikes the apple, the two objects stick together.
    So rewrite the above equation.
     
  4. Mar 9, 2009 #3
    Re: Momentum

    I don't get it
    If the momentum is 0 then the velocity is 0
     
  5. Mar 9, 2009 #4

    rl.bhat

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    Homework Helper

    Re: Momentum

    Momentum after impact = ( 0.1 + 0.08)*v
     
  6. Mar 9, 2009 #5
    Re: Momentum

    m1v1 = (m1 + m2)v
     
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