Subject: | |
From: | |
Date: | Thu, 1 Jun 2000 11:10:21 +0100 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
New Scientist magazine, 03 June 2000
Sweet symphony
OPENING sweets at the movies [and classical concerts] always creates
a disturbance. And now we know why. The crinkles in commonly used
wrappings such as Mylar and cellophane are to blame, says a
Massachusetts physicist.
"This class of materials seems to be almost uniquely suited for
producing very loud noises," says Eric Kramer of Simon's Rock College
of Bard in Great Barrington.
Kramer studied the sounds that pre-crumpled Mylar makes when it is
unwrapped and scrunched up again. He found that the unwrapping
cacophony is a series of individual clicks, caused by crinkles in
the material. They release energy as they go from one stable state
to another between being crumpled and flat.
As Mylar crinkles, polymer molecules shift and break. Some of these
changes are permanent, creating the crinkles themselves. But others
are reversible, storing just enough energy to make a din, Kramer
believes.
James Kearney
[log in to unmask]
|
|
|