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Homework Help: Finding velocity of a piece after explosion

  1. Nov 28, 2016 #1
    1. The problem statement, all variables and given/known data

    A firework of mass 1 kg is placed on the ground and ignited , the impulse created by the explosion causes it to move vertically upwards,after 4 seconds a second explosion takes place in air and the horizontal impulse forces cause it to separate into 4 identical pieces

    2 seconds after the 2nd explosion these 4 pieces travel horizontally in the same plane that the 2nd explosion took place and reach the vertices of a square of diagonal 80 meters

    Find the horizontal velocity imparted on a piece after the 2nd explosion ??

    2. Relevant equations

    P = m v
    P initial = P final

    3. The attempt at a solution
    1kg x 50 m/s = 1/4kg x (V1 + V2 + V3+ V4) m/s

    I cant figure out the what to do next
    Last edited: Nov 28, 2016
  2. jcsd
  3. Nov 28, 2016 #2


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    Hello goatz, :welcome:

    Your attempt is a bit feeble by PF standards....
    what are V1, V2, V3, V4 that you need four symbols ?

    The original piece of fireworks moves up, the statement tells us. Where is that v in your attempt ?
    Then it separates into 4 chunks that apparently fly off in a special manner. What are the parameters that describe their velocities? How do horizontal and vertical velocities develop in time ?
    What do you do with the 2 seconds ?

    Can you make a drawing of the sequence ?
  4. Nov 28, 2016 #3
    I actually figured it out , this whole time i was trying to apply linear momentum , that`s why i was stuck. You can simply get the answer by using V=S/T
  5. Nov 28, 2016 #4


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    I find that hard to believe. Can you show what you did ?
    [edit] never mind. I read post #1 a little better and I can follow you.
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