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Collision response of two object

  1. Apr 13, 2009 #1
    Hi,
    how can i find collision response between rectangle and circle like in this picture :


    attachment.php?attachmentid=18441&stc=1&d=1239613714.jpg

    i want to identify the direction and magnitude of V1 vector and the V2 vector after they collided , does anyone have some idea about this ?
     

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    Last edited: Apr 14, 2009
  2. jcsd
  3. Apr 13, 2009 #2

    tiny-tim

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    Welcome to PF!

    Hi knonk! Welcome to PF! :wink:

    (your picture doesn't show any vertex marked V1 or V2 :confused:)

    Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
     
  4. Apr 13, 2009 #3
    Okey, in this picture :

    attachment.php?attachmentid=18441&stc=1&,d=1239613714.jpg
    With :
    + V1 : initial velocity vector of Circle
    + M1 : mass of Circle
    + V2 : initial velocity vector of Rectangle
    + M2 : mass of Rectangle

    i want to identify the direction and magnitude of V1 vector and the V2 vector after they collided, does anyone have some idea about this ?
     
    Last edited: Apr 14, 2009
  5. Apr 14, 2009 #4

    tiny-tim

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    Hi knonk! :smile:

    (ah, you meant "vector", not "vertex"!)
    On this forum, the idea is that you do the work, and we give you hints :wink:, so …

    Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
     
  6. Apr 14, 2009 #5
    Please look at this picture :

    attachment.php?attachmentid=18482&stc=1&d=1239766977.jpg

    First, we consider that :
    + v1i : veloc vector of circle BEFORE they collide
    + v2i : veloc vector of rectangle BEFORE they collide
    + v1f : veloc vector of circle AFTER they collide
    + v2f : veloc vector of rectangle AFTER they collide​

    How to find V1f and V2f

    *Before the collision
    +Momentum of the objects:
    p1i = m1*v1i
    p2i = m2*v2i
    Pi = p1i+p2i​
    +Kinetic energy of the objects:
    ke1i = (1/2)*m1*v1i2
    ke2i = (1/2)*m2*v2i2
    KEi = ke1i+ke2i​
    *After the collision
    p1f = m1*v1f
    p2f = m2*v2f
    Pf = p1f+p2f​
    +Kinetic energy of the objects:
    ke1f = (1/2)*m1*v1f2
    ke2f = (1/2)*m2*v2f2
    KEf = ke1f+ke2f​
    *Apply the law of the conservation of momentum
    Pi = Pf = P
    m1*v1i+m2*v2i = m1*v1f+m2*v2f
    KEi = Kef
    (1/2)*m1*v1i2+(1/2)*m2*v2i2 = (1/2)*m1*v1f2+(1/2)*m2*v2f2​
    *Rearranging and combining the two equations above, we get the following:
    v1i-v2i = v2f-v1f
    V = v1i-v2i
    So,
    v1f = v2f-V ​
    *Using the above equation with the equation for P, we get the final results:
    v2f = (P+V*m1)/(m1+m2)
    v1f = v2f-v1i+v2i
    So we know the way how to find V1f and V2f,and we have this :
    V1i = V1;
    V2i = V2;​
    And m1,m2, so we can find v1f,v2f
    But seem they have something wrong but i don’t know,
    Uhm,Hope u can tell me. Thanks alot.
     

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  7. Apr 15, 2009 #6

    rl.bhat

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    When I see the picture, I feel that both rectangular block and circular block must possess translational and rotational motion.
     
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