ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
*****************************************************************************

In this case, the "pulley" isn't acting as a pulley.  In the parlance of a
simple machine, to be a pulley it must do one of three things:

   - change the direction of a force
   - transmit rotational motion
   - realize a mechanical advantage

In this case, the "pulley" is doing none of those things, and is acting as a
wheel and axle.

You can tell this by imagining that the rider and wheel on top of the zip
line... imagine a tight rope walker on roller skates.  You'd expect to buy a
set of wheels and axles, not a pulley.

----
Earl Stirling

Building SCIENCE!
e x p l  O  r a t o r i u m
3601 Lyon St
San Francisco CA 94123
+1.415.353.0401



On Tue, May 10, 2011 at 2:42 PM, Fournier, Kathy <[log in to unmask]>
wrote:
> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related
institutions.
>
*****************************************************************************
>
> Hey all:
>
> I need some help in settling a difference of opinion among my staff. We
> are writing up the science of a zipline for a new exhibit and there is
> some disagreement on whether or not the 2 simple machines involved are
> an inclined plane (they slope of the wire) and a pulley OR an inclined
> plane and a wheel and axle.
>
>
>
> I know this group will have plenty of insight so bring it on!
>
>
>
> Kathy Fournier
>
> Associate Vice President of Education
>
> McWane Science Center
>
> 200 19th Street North
>
> Birmingham, AL 35203
>
> 205-714-8254
>
> [log in to unmask]
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ***********************************************************************
> For information about the Association of Science-Technology Centers and
the Informal Science Education Network please visit www.astc.org.
>
> Check out the latest case studies and reviews on ExhibitFiles at
www.exhibitfiles.org.
>
> The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft.
To learn more, visit
> http://www.lsoft.com/LISTSERV-powered.html.
>
> To remove your e-mail address from the ISEN-ASTC-L list, send the
> message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
> [log in to unmask]
>

***********************************************************************
For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.

Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.

The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
http://www.lsoft.com/LISTSERV-powered.html.

To remove your e-mail address from the ISEN-ASTC-L list, send the
message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
[log in to unmask]