newton's cradle brings up a strang question?????

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why06

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Yeah... anyway here it goes. I was just sitting around playing with a genuine newton's cradle I got for five bucks...<br />First I just picked up one metal ball<br />-than two, than I started to get fancy with...<br />I dropped two balls simutaneously from the same hieght and the energy was transfored to two other balls. (I excluded the fifth ball as so the number of balls on each side would be even)<br />Later on I dropped a(1) ball from a taller height , but only one ball moved on the other end. No matter how much force and speed I added only won ball moved. <br /><font color="orange"><br />?How can it be that only only one ball moves when the force of that one is greater than the force of the combined two yet it was capable of moving two balls?<font color="white"><br /><br />I checked to see if the two balls were not leaving their position simultaneously, but no matter what I did the out come was the same. Does mass play a bigger role than thought in the transfer of energy.</font></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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mlorrey

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Because what you perceive as one strike is actually mutiple strikes that are exhibited as elastic shocks through the material of the balls.
 
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why06

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I thought about that ,but because I couldn't see it I put it a side. Thanks for the explanation <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>
 
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billyinthedarbies

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also, mathimatically both momentum and kinteic energy must be conserved. If one ball is dropped from a height of h and it causes two balls each to get to a height of 1/2h we see that momentum is conserved because mv=1/2mv+1/2mv. But when one observes the kenetic energy it is evident that the K is not conserved because the striking ball has a momentm of K = (1/2)mv2. Two balls with half the speed have K=(1/2)m(v/2)2+(1/2}m(v/2)2 = (1/4)mv2. (1/2)mv2 does not equal (1/4)mv2 therefore one ball can only cause one ball to be ejected from the other side at the same velocity and height.
 
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billslugg

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billyinthedarbies<br />Welcome to SDC! Thank you for this explanation. It is something I was unaware of. I have in my shop a set of 5 spherical bearing rollers, each about 6 pounds. Someday I will make a Newton's Cradle with them. The barrier I am facing is that I cannot figure out how to attach the wires. They are hardened steel, so drilling and tapping is out of the question. Actually I could drill them with carbide bits, but I am hesitant to tap a hole with a carbide tap. Imagine trying to extract a broken carbide tap from a hole in hardened steel. Then I would have to build an EDM machine, a project which is way far out on my list. I can't braze them because the mass of the roller would not allow it to get hot enough with my piddling flame. I guess I'll have to weld them on somehow. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>
 
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bitbanger

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<blockquote><font class="small">In reply to:</font><hr /><p>The barrier I am facing is that I cannot figure out how to attach the wires.<p><hr /></p></p></blockquote><br />Build a wire sling to hold the bearings. Then if you really need to attach the bearings to the wires, a little epoxy will do the trick.<br />
 
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