Movitation For Definitions In Physics

Bashyboy

Hello,

I noticed in my physics textbook that we define certain relationships to be true. I can see how this is considerably helpful in deriving other relationships from these definitions; for instance, take position: we define these quantities to be so, and from it we can define other quantities like velocity, acceleration, etc. Moreover, most of the time these definitions are well-grounded and intuitive. However, at other times they aren't. To serve as some examples: force, torque, and electric fields. How were these things defined? What was the reasoning used to define these quantities? What are the motivations for these definitions?

ModusPwnd

The motivation for all definitions in physics is to be able to create descriptive and predictive models of our observations. If we define force, torque, and electric fields the way we do, we get powerful models. If we define them other ways, we dont.

Bashyboy

So, the way in which we define something is somewhat of a result of "trial-and-error?" That is, keep trying definitions until we find a definition that best describes something or fits experimental data?

ModusPwnd

Yes, experiment is generally the final arbiter of whether a definition is useful. How you get the definition doesn't matter, trial and error, intuition, logic, wild guess, burning bush, whatever. Of course its interesting to read about how definitions came about, it gives insight into the process of science. But as far as theories of science are concerned, it doesn't matter at all how you come up with a definition. All that matters is if the definition increase our ability to predict and describe observations or not.