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posted by janrinok on Thursday December 15 2016, @05:23AM   Printer-friendly [Skip to comment(s)]
from the try-this-at-home dept.

Submitted via IRC for Bytram

A group of first year students at Roskilde University, supervised by Dr Tina Hecksher, have shown that water-filled balloons behave very similarly to tiny water droplets, by bouncing them on a bed of nails.

Their work, published today in the European Journal of Physics in collaboration with Professor Julia Yeomans at Oxford University, was inspired by one of Professor Yeomans' previous papers studying water droplets bouncing on hydrophobic surfaces patterned with lattices of submillimetre-scale posts.

Dr Hecksher said: "We wanted to know if the so-called 'pancake bounce' effect - where the droplet lifts off the surface at its maximal extension - which was observed in the microscopic experiments could be replicated on a macroscopic scale.

"Scaling up the experiment allowed us to measure the impact forces in the pancake bounce, which gave a deeper insight into its dynamics. It also provides a really useful teaching tool to demonstrate to students in a very cost-effective, straightforward, and eye-catching way how these forces work."

The study compared the impact of the balloons - taking the place of water droplets - landing on a flat surface and on a bed of nails - modelling the submillimetre posts. Using large store-bought party balloons, a digital reflex camera running at 300 frames per second to record the impact in slow motion, and a piezoelectric sensor under the board to log the impact force, the team measured impacts at different velocities and the balloons' resulting behaviour.

Source: http://phys.org/news/2016-12-balloons-bed.html


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  • (Score: -1, Offtopic) by Anonymous Coward on Thursday December 15 2016, @05:32AM

    by Anonymous Coward on Thursday December 15 2016, @05:32AM (#441522)

    your mother's tits bounced nicely while I fucked her.

    • (Score: 0) by Anonymous Coward on Thursday December 15 2016, @11:37PM

      by Anonymous Coward on Thursday December 15 2016, @11:37PM (#441846)

      Go home junior. The best trolls are the clever trolls. If you used "balloons" instead of "tits", it would have been much more clever. As it is, it is unfunny adolescent humor.

  • (Score: 2) by Marand on Thursday December 15 2016, @05:45AM

    by Marand (1081) on Thursday December 15 2016, @05:45AM (#441524) Journal

    It seems necessary for someone to link this song [youtube.com], so it may as well be me.

    (alternatively, here's an a cappella [youtube.com] cover, because why the hell not?)

    • (Score: 0) by Anonymous Coward on Thursday December 15 2016, @05:47AM

      by Anonymous Coward on Thursday December 15 2016, @05:47AM (#441525)

      Are you going to post the title or link to the lyrics, or are you a rickrolling trolling asshole motherfucker?

      • (Score: 0) by Anonymous Coward on Thursday December 15 2016, @05:51AM

        by Anonymous Coward on Thursday December 15 2016, @05:51AM (#441526)

        No, I'm gonna give you an opaque youtube link because I'm a fucking sack of shit like every other fucking sack of shit.

        https://www.youtube.com/watch?v=pc0mxOXbWIU [youtube.com]

      • (Score: 2, Disagree) by Marand on Thursday December 15 2016, @06:29AM

        by Marand (1081) on Thursday December 15 2016, @06:29AM (#441531) Journal

        Since you're a pansy baby that's afraid to click a youtube link, it's "Bed of Nails" by Alice Cooper. Or maybe it isn't. It's not like you'll ever know, since you're too paranoid to follow a link because you might accidentally hear Rick Astley for a couple seconds.

        • (Score: 4, Funny) by MostCynical on Thursday December 15 2016, @08:44AM

          by MostCynical (2589) on Thursday December 15 2016, @08:44AM (#441543)

          But he's never going to let you down, or run around and desert you.

          --
          Books are a poor substitute for female companionship, but they are easier to find. P Rothfuss “The Wise Man's Fear"
  • (Score: 1) by charon on Thursday December 15 2016, @07:21AM

    by charon (5660) on Thursday December 15 2016, @07:21AM (#441536)
    Can't wait til next year when this wins an Ig Nobel prize [improbable.com].
  • (Score: 0) by Anonymous Coward on Friday December 16 2016, @12:04AM

    by Anonymous Coward on Friday December 16 2016, @12:04AM (#441861)

    Would anyone really think "no"? You can comfortably lay down on a bed of nails, you can do that and have someone break a cinderblock on your chest using a sledgehammer with no problem (I can find a handful of YouTube links showing this, but I was trying to find a clip from the 70s or 80s where I remember William Shatner demonstrating this on some hokey show where TV stars do amazing feats of magic and skill). However, as is true with a lot of phys.org articles, the article is really not much about the glib article title.

    I do question the physics of what they're doing, namely using a water balloon as a macro-scale surrogate for the water droplet. I would want to convince myself that the party store balloons provide a similar force as does the water's surface tension for the enclosed respective volumes (IAAP, but not particularly interested in the problem to do the calculation). You might be getting more bounce with the balloon than you would get with the water droplet simply because the rubber (or whatever fancy polymer they use to make balloons out of these days) gives you a different elastic restoring force.

    On the other hand, it is a very nice demo/experiment to do at the undergrad level.