Why are some random physical quantitites given a name?

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Discussion Overview

The discussion revolves around the naming conventions of physical quantities, specifically questioning why certain derivatives, like ##\frac{dp}{dt}## (force), are given names while others, such as ##\frac{dp}{ds}##, are not. Participants explore the implications of naming on calculations and the perceived importance of various quantities in physics.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the rationale behind naming physical quantities, suggesting that if convenience in calculations is a criterion, then ##\frac{dp}{ds}## should also have a name, proposing the term 'x-force'.
  • Another participant expresses skepticism about the importance of naming ##\frac{dp}{ds}##, implying that it may not be significant in the broader context of physics.
  • A different participant acknowledges that while naming may not seem important, the ability to perform calculations with the quantity is valid.
  • One participant suggests that the naming of quantities may depend on factors such as frequency of use, relationships to other quantities, and derivability from other quantities, citing 'jounce' as an example of a named but rarely used quantity.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the importance of naming physical quantities, with some expressing indifference while others argue for the significance of naming based on utility in calculations.

Contextual Notes

There are unresolved assumptions regarding the criteria for naming physical quantities and the implications of those names on their perceived importance in physics.

Kumar8434
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##\frac{dp}{dt}## is given the name 'force' but ##\frac{dp}{ds}## has no name. I know 'force' is useful for calculations and predicting the future of the system. If 'convenience in calculations' is the reason why some quantities are given names, then I don't see why ##\frac{dp}{ds}## doesn't have a name.
Let's call ##\frac{dp}{ds}## 'x-force' denoted by ##x##. Then if x-force is a function of time ##x(t)##, then,
$$\int_{t_1}^{t_2}x(t)dt=m(\ln(v_2)-\ln(v_1))$$
which looks similar to the work-energy equation:
$$\int_{s_1}^{s_2}F(s)ds=\frac{1}{2}m(v_2^2-v_1^2)$$
So, x-force can also be used for calculations but is not given a name. Then, what is the basis for calling a physical quantity important and giving it a name?
 
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Kumar8434 said:
Let's call dp/ds 'x-force'...
Yeah, call it what you want, and then go on to stuff that actually matters.
 
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A.T. said:
Yeah, call it what you want, and then go on to stuff that actually matters.
If you don't like the name, then maybe use ##force'##. But why doesn't it matter? I've shown that we can also do calculations with it and predict the future of a system.
 
Kumar8434 said:
But why doesn't it matter?
If it matters to you, name it what you want and be happy.
 
There's no simple answer to your question, but I'd bet some factors include how often these quantities are used, their relationship to other quantities, whether they can be derived from other quantities or not, along with other factors. Some quantities have names but are rarely used. For example, the 2nd derivative of acceleration is known as jounce, but you probably won't encounter that term very often.
 

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