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Um, how does this make sense?

  1. Sep 19, 2004 #1
    Hey guys, im a new member here and i dont know that much about physics so if this seems really obvious to you sorry, im only 15!

    Ohk heres my problem.
    I was looking at some stuff on impact
    Now impact is reliant on impulse yes?
    Now if I(impluse) = F average * change in time
    And impulse is = momentum
    momentum is Mass * Acceleration, or delta v / delta t
    So if a bird is travelling at a velocity of 10m/s with a mass of 10kg but has no acceleration and it collides with an aeroplane which is travelling at 80m/s with a mass of 12 tons with no acceleration does that mean there is no impact as there is no acceleration?
     
  2. jcsd
  3. Sep 19, 2004 #2

    Tide

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    When they collide each object undergoes acceleration - the bird moreso than the airplane! :-)
     
  4. Sep 19, 2004 #3
    Oh i see, it all makes sense now thnx
     
  5. Sep 19, 2004 #4
    oh im an idiot i see now, p = mv, not ma, ma is f... oh well i feel dumb now, should probably get my formulae right first
     
  6. Sep 20, 2004 #5

    Doc Al

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    Staff: Mentor

    incorrect signs

    Not exactly. The net change in momentum is zero, so:
    [tex]m_1(V'_1-V_1)= -m_2(V'_2-V_2)[/tex]
    Again, your signs are incorrect. If the collision is elastic (certainly not the case for the bird hitting the plane!) then KE is conserved, so:
    [tex]m_1V'_1^2 + m_2V'_2^2 = m_1V_1^2 + m_2V_2^2[/tex]
     
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