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The Physics of a Rolling Rubber Band

Posted by CmdrTaco on from the thank-god-that-is-solved dept.

sciencehabit writes "Modern physics can get complicated. Sure, researchers know exactly what forces act on a ball rolling down an incline — an experiment that helped Galileo develop universal laws for movement and acceleration. But what happens when a deformable shape like a rubber band rolls around? A new study reveals that the faster it goes, the more squashed it gets (video included)."

18 of 226 comments (clear)

  1. Physics... by Pojut · · Score: 3, Insightful

    ...is mind-boggingly awesome. I can't understand the math at all, but I understand the way things generally act. So cool (and so insanely complicated! Think about something like a key being inserted into a lock...and that's just simple, everyday stuff!)

    --
    Living With a Nerd
    1. Re:Physics... by SpinningCone · · Score: 4, Interesting

      i agree. I always liked physics made the world look different (like "car breaks are kinetic to thermal energy converters"). never could really get into dynamics though. i remember my teacher describing the the problem of rotational inertia of a deformable object (like a jelly disk) faster you spin the more it changes shape which changes its inertia.

      props to the people out there with the knack and persistence to solve crap like that.

    2. Re:Physics... by Anonymusing · · Score: 4, Funny

      Physics is pretty cool.

      I liked this quote from the article:

      As far as the potential applications, Clanet waxes futuristic. "I can imagine [designing] a car. The faster it goes, the more it deforms and the less friction it has with surrounding air, so it can go even faster. It would be a fantastic car."

      A car that changes its shape as it drives? Getting shorter, even? "Ouch, slow down, you hit my head!"

      Automobile safety experts would have a field day with that.

      --
      Liberal? Conservative? Compare perspectives at Left-Right
    3. Re:Physics... by EdZ · · Score: 3, Insightful

      Because air behaves differently at different speeds. Once you got fast enough, shockwaves become the limiting factor rather than fluid fraction. Then you have cavitation, and things like compression heating. What is most efficient at one speed is not most efficient at all speeds.

    4. Re:Physics... by VolciMaster · · Score: 3, Funny

      I love Ben Rich's quote on that: "no one's been wing-walking at Mach 3 to verify that assumption" :)

      --
      antipaucity
  2. Wow, interesting! by rotide · · Score: 4, Interesting

    If you would have asked me how it would react as it rolled faster and faster, I would have just assumed it would have gotten "rounder" and possibly larger (elastic) due to centrifugal force.

    Always amazes me how things don't always work as expected. Nature, physics, etc, are truly interesting... no, fascinating. Now if only I had a better grasp of higher level maths and wasn't a Network Engineer (data plumber).

    1. Re:Wow, interesting! by Spad · · Score: 3, Funny

      ...due to centrifugal force.

      My high school physics teacher used to electrocute (With a handheld generator made from a rotary pencil sharpener) people for saying that; also for misspelling accelerate or satellite.

    2. Re:Wow, interesting! by ledow · · Score: 4, Interesting

      Yes, but then people "weigh" themselves in kg's by standing on a scale that is affected by gravity.

      There are certain things that, although "visible" by ordinary people and named, don't actually exist or exist only because we *perceive* them to exist, like that optical illusion with the white triangle that isn't ACTUALLY there.

      Centrifugal force may be misnamed (i.e. not a force), it may be incorrect, but it's generally accepted that "a force" exists that has an effect on your when you're spun in a circle. Just because the direction / origin / name of that force is incorrect is no reason to tell people that they're stupid for having felt it and knowing what it is before you explain its origins.

      Back in the 60's there was an advertising campaign by scientists working on the behalf of government to target heat loss in elderly people's properties. It encouraged old people to "keep the heat in". It didn't go down well and it took them years to discover why. Eventually it was changed to "keep the cold out" and more elderly people understood that. "Cold" doesn't actually exist, it's just the absence of heat, but old people didn't think that way as easily (and who can blame them? "Shut the door, you're letting the cold in" is a common cry in my family - despite the fact that you're neither letting cold in nor arranging for some mystical "cold" entity to enter your property rather than, say, air with slightly less heat).

      There's 100% pedantic accuracy. There's complete bollocks. And somewhere in the middle is how *everybody* thinks, even if they know both extremes in detail.

  3. Brakes, please. Please? by Kupfernigk · · Score: 4, Informative

    I'm sorry but this is such a common mis-spelling on Slashdot that it's getting to me. Cars have brakes. "Car breaks" means it stops working because of mechanical or electrical failure. Spellcheckers can't fix homophones.

    --
    From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
    1. Re:Brakes, please. Please? by Anonymous Coward · · Score: 4, Funny

      Spellcheckers can't fix homophones.

      I can tell you have your spellchecker on, though I think you ment to write "homophobes".

      I too believe they should be fixed.

    2. Re:Brakes, please. Please? by Bromskloss · · Score: 3, Funny

      Cars have brakes. "Car breaks" means it stops working because of mechanical or electrical failure.

      I honestly thought he was talking about car crashes and even though that was a strange way of saying it, I convinced myselft that is was physically sound.

      --
      Swedish plasma phys. PhD student; MSc EE; knows maths, programming, electronics; finance interest; seeks opportunities
    3. Re:Brakes, please. Please? by boxwood · · Score: 3, Funny

      a bit of tape stuck over the bottom left corner can fix a homophone.

  4. Re:Delight to read... by Spad · · Score: 4, Funny

    I like to imagine that all scientists operate on this principle. They sit around doing boring paperwork until one of them says "I wonder what happens when a deformable shape like a rubber band rolls around?", to which one of the others replies "Quickly, to the lab!" and they all run off to investigate it.

  5. Direct link to the .FLV by Anonymous Coward · · Score: 3, Informative

    For those of us where the player won't launch when you click "play video" in the article, here's a direct link to the flash video:

    http://sciencevideo.aaas.org/sciencenow/snow_ribbon_250.flv (320x240, 17 seconds, 1.1MB)

  6. This requires Yakety Sax by cangrande · · Score: 5, Funny

    All science videos are improved by Yakety Sax.

  7. Miracle by JustOK · · Score: 5, Funny

    Fucking rubber bands, how do they work?

    --
    rewriting history since 2109
  8. Flying out of the drum by azmodean+1 · · Score: 3, Interesting

    I was amused by this aside:

    (The team couldn't study what happened when the two sides touched: The friction of the two sides moving in different directions sent the rubber bands flying out of the drum.)

    What? It seems pretty obvious that they could see exactly what happened when the two sides touched, "The friction of the two sides moving in different directions sent the rubber bands flying out of the drum".

  9. Obvious by wcrowe · · Score: 3, Funny

    A new study reveals that the faster it goes, the more squashed it gets.

    Well duh. Of course it does. Anyone who has watched a Roadrunner cartoon knows that.

    --
    Proverbs 21:19