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Newtons cradle

  1. Jun 18, 2005 #1
    have been trying to make me own workig newton cradle. I know some physics. the problem is that my balls don´ta completely stop moving after the coalition, they rather continua their movement but with a reduced violocity. This typ of movement increases and grows with the number of coalitions. At the end all of the balls move with eatch other. And thats not what i want. The balls i have been using are glas or stone balls. I could not get my hands on metal balls. Can that be the reason for this failure?
  2. jcsd
  3. Jun 18, 2005 #2


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    Friction at the point where you attached the ball's to the support and loss of energy in inelastic collisions. Metal balls are much more elastic than glass or stone.
  4. Jun 18, 2005 #3
    Thanks for replaying. I dont think friction is the answer to why the movement of the balls are not the way they are supposed to be. Friction can only explain why do movement slows down and gradually ends. The collision is inelastic, that means that the kinestic enegy turns into heat but how can this effect the type av movment?
  5. Jun 18, 2005 #4


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    It could be that your balls don't have equal masss.
  6. Jun 19, 2005 #5
    What if the first collision were totally inelastic? This would be the case if the balls were made of something that deformed without springing back, like clay. Don't you think that would "effect the type av movement"?
  7. Jun 19, 2005 #6
    Still, it does not make sense. Stone balls should be elastic enought to get the desired type of movement. I mean, what type of balls did Netwons himself use? Did he not use stone balls? I think he did.
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