ADVERTISEMENT
  About the SA Blog Network













Observations

Observations


Opinion, arguments & analyses from the editors of Scientific American
Observations HomeAboutContact

Gravity-Defying, Self-Siphoning Metal Beads Explained [Video]

The views expressed are those of the author and are not necessarily those of Scientific American.


Email   PrintPrint



The effect is as astonishing as it is hypnotic: a chain of metal beads magically arcs above its container as the beads fall to the ground. The beads in the video, made by Steve Mould, who hosts several BBC science shows, are not magnetic, either.

Pretty cool, huh?

Mould gives us an explanation the video below, which offers a super slow-motion view of the effect. In a nutshell, the gravity-defying effect is the result of inertia: the beads moving out of the glass cannot instantaneously change momentum to follow the beads falling down. Instead, they gradually change course and assume a curved path out of the glass. Notice the little standing-wave kink that forms on occasion, too.

You can really get into the physics in this post on the blog Empirical Zeal by Aatish Bhatia. The explanation is also Bora’s Video of the Week.

Philip Yam About the Author: Philip Yam is the managing editor of ScientificAmerican.com. Follow on Twitter @philipyam.

The views expressed are those of the author and are not necessarily those of Scientific American.





Rights & Permissions

Comments 2 Comments

Add Comment
  1. 1. Gauger 10:27 pm 04/1/2014

    The chain is acting like a whipcrack. The wave of force is actually rising up from the longer, heavier, end of the chain.

    But since the chain is semi-rigid it cannot form a corner, it will always form a curve (even if you tried to crush it in your hand, it will still form a curve, rather than bend sharply.)

    With the force rising from the bottom, force always tries to move forward and follow the path of least resistance, in this case, rising up as high as possible compared to the weight of the chain.

    At the top of the curve is where a whip would normally “snap” flipping up the end and dissipating the force.

    But since there is more chain there on the other side, it cannot simply disipate, it must continue to try to travel along the chain, in this case, pulling up the lighter end of the chain as the wave travels along it.

    The “corkscrews” are likely a result again of the semi-rigid nature of the chain, as well as the force’s nature to travel in as straight a line as possible, with the least resistance.

    If portions of that chain are tangled in the jar, the force will automatically unravel the chain, straightening it out and turning it so that the force can continue to travel in a straight line with the least resistance.

    The result is the corkscrewing phenomenon. Not unlike how we will “snap” a garment to untangle it, or “snap” an electrical power cord or hose to send a wave along it to “untangle” a twisted section.

    It is mainly due to the extreme length of the chain that allow those loops and curves to be seen as “standing” forms, since they are literally being held up by the captive force of the wave which cannot dissipate until it reaches the end of the chain, or until the heavier end of the chain is made lighter or equal to the weight of the chain in the jar.

    The way to test that, would be to grab the longer chain as it is falling, at a distance equal to or shorter than the level of the resting chain in the jar, if this is correct, the wave will collapse.

    Link to this
  2. 2. Munmunnishi 1:13 am 07/8/2014

    WOW!
    Excellent Video.I also like it.Fantastic Blog.I wait your next amazing blog.
    Thanks a lot for sharing this article and post.
    Munmun Nishi.

    Ghana Beads “

    Link to this

Add a Comment
You must sign in or register as a ScientificAmerican.com member to submit a comment.

More from Scientific American

Scientific American Special Universe

Get the latest Special Collector's edition

Secrets of the Universe: Past, Present, Future

Order Now >

X

Email this Article

X