On Sun, 27 Mar 2005 05:30:52 GMT, "Don"
wrote:


"Richard Cline" wrote in message
...
In article ,
"Greg O" wrote:

"Don" wrote in message
k.net...
Won't expanding the pulley make the hole smaller?



Nope, when you heat a ring shape, such as a pulley, the hole will get
larger.
Greg


Is that because the air in the hole expands more than the metal and
forces it to be bigger?

I wonder what scientific property allows one portion of the metal to expand
(the outside surface of the pulley) while the other part contracts (the
hole).



the hole isn't part of the metal. it's where the metal isn't. look at
it like this: say you have a piece of wire. you heat it, it expands
and gets longer. now say you bend it into a circle. you heat it, it
gets longer. the corcle gets bigger, both inside and outside diameters