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Homework Help: Ratio of momentum conserved

  1. Oct 29, 2008 #1
    1. The problem statement, all variables and given/known data
    A 6.91x106 kg spherical space ship in deep space explodes into two pieces, one 4.77 times the mass of the other.
    a) Suppose the ship is initially at rest, and after the explosion the smaller piece is moving 57.6 m/s.
    - Find the speed of the larger piece.
    -Find the energy supplied by the explosion.

    2. Relevant equations

    3. The attempt at a solution
    I tried establishing a ratio of the masses equals the ratio of the velocities and got -12.075 m/s for the larger piece. but got it wrong,
    and the second question needs .5(m)(v2) but i dont know the velocity of the heavier mass.
    Is there a flaw in my reasoning

    Thanks for your help
  2. jcsd
  3. Oct 29, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks OK to me, except for the minus sign. (Speed is just a magnitude, thus always positive.)
  4. Oct 29, 2008 #3
    I tried the answer it says its wrong... and then...
    c) Suppose the ship is initially moving at constant velocity +18.2 m/s. After the explosion, the smaller piece is moving -57.6 m/s (in the opposite direction to the initial velocity), Find the velocity of the larger piece.

    i tried it the same way but with starting momentum 18.2(Mtotal)... and got +9.94... and it says this is wrong as well
    is my reasoning flawed? and i double checked my calculations... HELP
    Last edited: Oct 29, 2008
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