Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Pb

PHYS-L@lists.nau.edu writes:
To demo this kind of transformation I drop a steel ball onto a one of
the temperature sensitive color changing post cards (the Exploratorium
sell these). The card must be on a hard floor. A color change occurs at
the point of impact. Pressing the ball against the card and floor with
great force and effort causes no change in color. Dropping the ball on a
piece of wood with the card in between also causes no change in color.
Demo leads to great student discussion regarding where energy is being
transferred.

HTH
Scott

Doesn't the impact damage the micro-encapsulated liquid crystal? Are you
sure you are looking at a temperature change and not a physical damage
artifact?

I have done this with a LARGE (2kg) iron ball onto a section of 1x4 and
then placed the LC card on the spot where it hit and noticed a very nice
temperature rise.

P. Lohstreter "If we want to solve a problem
that
US Science we have never solved before,
Chemistry & Physics we must leave the door to the
unknown ajar."
214-360-6389
Richard Feynman