Which Definition of Physical Quantity is Clearer and More Accurate?

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The discussion centers on the clarity and accuracy of definitions for "physical quantity." Participants critique the definitions provided, arguing that they are vague and imprecise, particularly the use of terms like "anything" and "measurement." A consensus emerges that a physical quantity should not only be measurable but also calculable, with examples like photons illustrating that not all physical quantities pertain to matter. The need for clearer definitions of terms such as "measurement" and "physical" is emphasized to enhance understanding. Ultimately, the conversation highlights the complexity of defining physical quantities accurately.
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Which definition is more clear and correct ?
1)Any thing that has a measurement is called a physical quantity.
2)Characteristics that can be given to a matter is called physical quantity.
 
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johncena said:
Which definition is more clear and correct ?
1)Any thing that has a measurement is called a physical quantity.
2)Characteristics that can be given to a matter is called physical quantity.
I would say that neither are correct. A physical quantity can not only be measured, but also calculated. And a photon is not matter, but has several physical quantities.
 
What about this one ?
Any thing that has a measurement and can be expressed in the form of a number is called physical quantity.
 
Eh, in my opinion, both are highly unclear and imprecise definitions...though I'll pick 1) if I had no choice. A physical quantity would be a physical property that, as its name suggests, is quantifiable. "Anything" is a terribly vague term, as is "measurement".
As for 2), "Characteristics" is too broad and sweeping a term - colour for example is most definitely not a physical quantity.
 
johncena said:
What about this one ?
Any thing that has a measurement and can be expressed in the form of a number is called physical quantity.
Again, what about calculating a physical quantity? And you need to define 'measurement', before you can use it.
 
Hootenanny said:
a photon is not matter, but has several physical quantities.

Why photon is not considered as matter?
 
johncena said:
Why photon is not considered as matter?

well its more accurate to consider it as a packet of energy, keeping in mind matter can be turned to energy and vice versa , i think 'physical' itself should be defined , maybe even some criteria to differentiate physical from non-physical.
 
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