Physics of a Unicycle.

General
1

Howdy all of you Unicycling fanatics out there. I have come up with an interesting task that will just occupy some of your time if you feel like participating. Heres your task:

 Show me the Physics of a Unicycle using whatever means you feel to present to me information revolving around "center of mass".  This should be done for a 24" miyata unicycle.  Rotational Kinematics information will also be appreciated if supplied.  If you feel like determining the distance traveled/distance pedaled be my guest, but I am basically looking for Center of Mass information.

Diagrams would be greatly appreciated, but not necessary.

Thank you all who feel like participating.

You can mail me responces to Monojankuf@yahoo.com or Monojankuf@unicyclist.com, or simply post a responce.

Once again, thank you.

–Kevin Jankowski

2

Are we doing homework for you, or are you just fascinated by centroids? If for some strange reason it is the latter, then you will definately have to give us more info. The question is like “please tell me science (for my teacher).” Where would one begin?
-gauss

3

right back atcha

To Guass,

To be honest, it does have to do with school, but not school as of now, but later. You see, I decided to re-teach myself Chemistry, Physics, and a little bit of Biology through the summer before my entrance into college. And playing around with Physics, and playing around with my Unicycle, I just kind of wondered how it worked. Now, I looked up problems on the internet, and found one relating to Center of Mass and a Unicycle. In my High School Physics class, we hardly, if ever touched on Center of Mass, and was wondering if one of those friendly unicyclists out there knew what the problem was asking for. As for more information, you are provided with as much information as I am. Its a 24" Miyata Unicycle, and what are the physics that go with it to make it work? Why is it possible to ride? Friction, gravity, work, momentum, force (and force cancelations) all work together to make it work. I was just wondering what the center of mass part of it was. And where is it on the unicycle. I think it is above the crank arm axis a little bit, but I am not sure, since I don’t really know what I am talking about.

4

RE: Physics of a Unicycle.

> I was just wondering what the center of mass part of it was.
> And where is it on the unicycle.

It isn’t. A unicycle does not ride by itself; only with the addition of a
person (or orangutan or chimpanzee) is it a viable vehicle.

The assumption is that the rider is many times heavier than the unicycle,
and the center of mass is roughly somewhere back of the rider’s belly
button. Sorry, not very technical. But the exact location is going to vary
with each person, each unicycle, and with any other weight they’re carrying,
such as clothing.

Also, I think you can leave out the wheel from most of this “center”
figuring, as it is the part that gets adjusted to correct the balance. The
part of the unicycle from the wheel bearings up gets counted along with the
rider as the moving part, with the center of mass in it.

The unicycle is ridden by moving both the pedals and the body, adjusting the
relationship between the center of mass and the contact point of the tire
with the ground.

I never took a physics class, but I think it’s a combination of several
different type of physics concepts, used together, that make a unicycle
work.

Watch videos of people doing tricks and riding trails and Trials to see the
physics in action. You can learn a lot by watching people move.

Enjoy,
John Foss, the Uni-Cyclone
jfoss@unicycling.com

“Vehicularly-Injured Sperm-Count seat: better known by it’s abbreviated
name, Viscount.” David Stone, on saddle preference

5

Re: Physics of a Unicycle.

monojankuf pleaded:
> Show me the Physics of a Unicycle …

Simple answer - imagine an object in orbit around the Earth. The object is
constantly falling towards the Earth due to gravity, but the Earth is
falling away at the same rate.

Now imagine a unicyclist. The unicyclist is constantly falling forwards,
but pedalling at just the right rate to keep up.

–
Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny )
B4/5v c(+) rv d m(+) w++ q+ k e+ t+ (s) g+ f - http://www.lpbk.net/jc/
“I don’t think proofreading is adequate. All posts should be waxed and
buffed. Then they should wear little tuxedos.” - Greg Harper on usenet

6

Re: Physics of a Unicycle.

monojankuf pleaded:
> Show me the Physics of a Unicycle …

Simple answer - imagine an object in orbit around the Earth. The object is
constantly falling towards the Earth due to gravity, but the Earth is
falling away at the same rate.

Now imagine a unicyclist. The unicyclist is constantly falling forwards,
but pedalling at just the right rate to keep up.

–
Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny )
B4/5v c(+) rv d m(+) w++ q+ k e+ t+ (s) g+ f - http://www.lpbk.net/jc/
“I don’t think proofreading is adequate. All posts should be waxed and
buffed. Then they should wear little tuxedos.” - Greg Harper on usenet

7

Re: Physics of a Unicycle.

On Fri, 17 May 2002 10:40:33 -0700, John Foss <john_foss@asinet.com>
wrote:

>A unicycle does not ride by itself; only with the addition of a
>person (or orangutan or chimpanzee) is it a viable vehicle.

Are you kidding John? (Looks to me like a “broodje aap verhaal”, but I
don’t know if that would make sense in translation.)

Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“SWAT, Richard Reid, CCSC”

8

Re: Physics of a Unicycle.

This was intended as a personal reply, but the address
monojankuf.4rq6m@timelimit.unicyclist.com
bounced, so I’m posting it to the list.
It may be of interest to other people anyway.

------- Start of forwarded message -------
Hi Kevin,

>Show me the Physics of a Unicycle using whatever means you feel to
>present to me information revolving around “center of mass”. This
>should be done for a 24" miyata unicycle. Rotational Kinematics
>information will also be appreciated if supplied. If you feel like
>determining the distance traveled/distance pedaled be my guest, but I am
>basically looking for Center of Mass information.

Attached please find an old message that might be useful.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

>From owner-unicycling@mail.winternet.com Mon Jan 31 20:58:30 2000
MIME-Version: 1.0
X-Authentication-Warning: icicle.winternet.com: server set sender to owner-unicycling using -f
From: “Stroessner, Wolfgang” <wolfgang.stroessner@sap.com>
To: “‘Joel Gilmore’” <rahvin@unbounded.com>,
“Unicycling (E-mail)”
<unicycling@winternet.com>
Subject: RE: Unicycling physics!!!
Date: Mon, 31 Jan 2000 11:33:27 +0100
Content-Type: text/plain;
charset=“iso-8859-1”
X-MIME-Autoconverted: from quoted-printable to 8bit by icicle.winternet.com id EAA06038
Sender: owner-unicycling@mail.winternet.com
Precedence: bulk
Reply-To: “Stroessner, Wolfgang” <wolfgang.stroessner@sap.com>

Joel Gilmore wrote:
> I know that there’s an article floating around on the physics of
> unicycling, but I can’t seem to put my finger on it. Does
> anybody know
> the URL (or any other URL to the physics of this wonderful passtime?)

To my knowledge it’s not available on the net. But you can probably get it
at the physics department of any university library. That’s the way where I
got a copy. The article is relly worth being read. I only have a copy on
paper. Otherwise I would send it per e-mail.

Best regards,
Wolfgang

          \\\|///
          | ~ ~ |
         (- 0 0 -)

±---------oOOo-()-oOOo----------------+
| |
| Wolfgang Strößner |
| |
| eMail: wolfgang.stroessner@sap.com |
| http://private.addcom.de/stroessner |
| Oooo. |
±--------.oooO-----( )----------------+
( ) ) /
\ ( (/
_)

>
>
>–
>monojankuf
>------------------------------------------------------------------------
>monojankuf’s Profile: http://www.unicyclist.com/profile/932
>View this thread: http://www.unicyclist.com/thread/18152
>
>___________________________________________________________________________
>rec.sport.unicycling mailing list - www.unicycling.org/mailman/listinfo/rsu
>
------- End of forwarded message -------

9

I don’t know if this will help but it sure looks interesting… http://www.math.lsa.umich.edu/~zenkov/papers/unicycle.pdf
I think they may be trying to say “pedal, pedal, pedal”