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Re: [Phys-l] Work and Energy: which first?



Modeling defines the energy stored in a spring as the area under the force
distance curve for a spring. Once the idea of a spring storing energy is
defined, other places to store energy are related to this by experiments.

In reality you have to start with a definition at some point. Minds on
Physics has students calculate mV^2 and compare it to F_g distance of fall
of a falling body without air resistance. At that point working is F
distance parallel and it is related to 1/2 m V^2.

In both approaches there is a physical or thought experiment which is then
related to a definition, not the other way around.

John M. Clement
Houston, TX



I'm thinking about how to teach work and energy to my introductory
class. I like the interpretation of work as a mechanical transfer of
energy, as I think it clears up the sign issues. However, I've seen
energy defined as "the ability to do work", which of course dumps us
into a circular definition. Outside of that, however, I'm not sure
how to define energy in general.

How do other people handle this chicken and egg problem?