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Re: [Phys-L] defining energy



Following up on John Clement's comments about gasoline and oxygen, I found
when teaching a distance education version of Matter & Interactions for
in-service high school physics teachers that many of them were surprised to
discover that they had been carrying around a view of binding energy that
was basically backwards, with the wrong sign. The view was something like
"there is energy stored in the bonds in the gasoline molecules which we can
use" instead of "in combustion the molecules transition to a lower energy
state and become more bound". To put it another way, they seemed to have
thought that "more" in the bonds (more binding) meant more "bond" energy
was available, instead of more bonding being associated with lower energy,
not higher.

I'll admit I can't express the issue very clearly, but the teachers
themselves were convinced that useful energy resulting from transitions to
lower energy levels (greater binding) was a new idea for them.

Bruce