Physics

Gravity-Defying Beads Make Fountain-Like Motion Before Tumbling

It's gravity that adds amusement to Physics and no wonder without it, life on Earth wouldn't have been possible. The video shows metal beads leaping out of a jar.

It’s gravity that adds amusement to Physics and no wonder without it, life on Earth wouldn’t have been possible. The video below shows a 50-meter string of metal beads leaping out of a jar making a fountain like motion of a chain before tumbling to the ground.

The chain’s phenomenal gravity-defying behavior has puzzled millions around the world and the creator of the video, Steve Mould has one explanation, that is – inertia –  the chain has to be taken to the lip of the jar before freeing and once it’s freed, the falling beads will trigger downward momentum, causing an upward momentum in beads leaving the jar.

The downward motion of the beads move apace and can’t change the direction straightaway. So it retains its upward motion, slowly changing its direction.

Physicist John Biggins of University of Cambridge, UK says Steve’s explanation was clever. He and his colleague, Mark Warner undertook an equation describing the chain’s gravity-defying behavior and discovered that Steve’s intuitive explanation was wrong.

“If inertia were causing the flowing fountain, the chain would be stationary at the top of the curve, says Biggins, in the same way that a ball tossed into the air is stationary at its highest point. “If that were true, it would mean the chain would pile up in the top region, which we don’t see.”

After a rough effort with the calculus they found that the creation of the fountain-like motion of the chain depends not on inertia, momentum, or gravity, but on the upward thrust generated from the end of the chain inside the jar.

[Source: Nature; Video Credit: Steve Mould]

9 comments

  1. What good luck I have had! This site is FULL of fascinating fun! Thanks so much. I will, though, have to ration my time going through these videos, or no work will be accomplished today. Many thanks, Maggie

  2. I presume by “the end of the chain inside the jar” they mean the end of the moving part of the chain, rather than the actual end of the 50m chain…? Otherwise I can’t begin to make sense of their explanation.

    1. While drawing an arc, there should be a starting point, right? That starting point is known as the “end”. According to the post, while the chain is leaping out of the jar, the chain creates a continuous arc motion for every loop it makes and is always associated with its end or the starting point.

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