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Homework Help: Velocity of broken parts

  1. Sep 10, 2010 #1
    1. The problem statement, all variables and given/known data
    A plane of a mass 5000 kg moving horizontally in 150 m/s break in to two parts 2000 kg and 3000 kg because of a internal explosion. If the bigger part be thrown away with a 400 m/s relative to other part to opposite direction of previous moved direction before explosion, find the velocity of each part. [Ignore the air resistance]

    2. Relevant equations
    Conservation of momentum

    3. The attempt at a solution

    I tried this, but I failed to do this one.

    I don't know this is right or wrong
    According to conservation of momentum

    5000 x 150 - 3000u = 5000 x (400 - 150) - 400 x 3000
    3(400 - u) = 50
    1200 -3u = 50
    1150 = 3u
    u = 383.6

    color black = Initial momentum of whole plane,
    color blue = Initial momentum of 3000 kg part
    color lime = final momentum of 3000 kg part
    color red = final velocity of whole plane

    The part in red or final velocity of whole plane. Is it right to take like that. I multiplied mass by the difference of initial velocity of plane and final velocity of 3000 kg part.

    Please help me to do this
  2. jcsd
  3. Sep 10, 2010 #2
    According to the answer script, the two velocities are 310 m/s and 90 m/s. My all tries are went wrong. I could not reach to this.
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