Why is force vector F but acceleration vector a not A?

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Discussion Overview

The discussion revolves around the conventions of using upper and lower case letters to denote vectors in physics, specifically questioning why force is often represented with an upper case letter while acceleration is not. Participants explore the historical and contextual reasons behind these notational choices.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that there seems to be a convention where velocity and acceleration are typically represented with lower case letters, while force is represented with an upper case letter.
  • Others argue that there is no strict rule governing the use of upper or lower case letters, suggesting that context plays a significant role in determining notation.
  • One participant mentions that the letter A is commonly used for area, while V can represent volume or electrical voltage, indicating that certain letters have established meanings that can conflict with vector notation.
  • Another participant reflects on the chaos that could arise from inconsistent notation across different contexts, emphasizing the importance of clarity in defining notation in scientific work.
  • It is suggested that different people may adopt varying notation schemes, and that these can change depending on the situation, particularly in handwritten work.
  • Areas of Agreement / Disagreement

    Participants generally agree that there is no universal rule for the use of upper or lower case letters in vector notation, and multiple competing views on the topic remain. The discussion does not reach a consensus on a definitive standard.

    Contextual Notes

    Participants highlight that the choice of notation may depend on historical reasons and specific contexts, which could lead to confusion without clear definitions.

TheCelt
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Is there some rule or standard that determines whether we define a vector with upper or lower case? I have not been told of any particular rule but it seems with velocity and acceleration they are lower case but force has always been upper case from what I've been reading so far.

Is there a rule to it?
 
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TheCelt said:
Is there some rule or standard that determines whether we define a vector with upper or lower case? I have not been told of any particular rule but it seems with velocity and acceleration they are lower case but force has always been upper case from what I've been reading so far.

Is there a rule to it?
There are far more quantities than letters, so they are used in multiple ways. It's the context - if at all - which gives some standard notations. Yes, acceleration and velocity have usually lower case letters and Force an upper case. But think about that they are in conflict with Ampère, Volt and frequency. All these have presumably historic reasons. It's similar in math: vectors are usually written as ##u,v,w##, but if you have groups and vector spaces at the same time, then it's convenient to write ##U,V,W## and reserve the lower case letters for the group elements.

The only thing for sure is, that ##f=A\cdot M## or ##u=r\cdot i## will raise a lot of questions.
 
Last edited:
TheCelt said:
Is there some rule or standard that determines whether we define a vector with upper or lower case? I have not been told of any particular rule but it seems with velocity and acceleration they are lower case but force has always been upper case from what I've been reading so far.

Is there a rule to it?
The letter ## A ## is usually used for area. Similarly, ## V ## usually means volume, or electrical voltage, while ## v ## means velocity. The letter ## T ## is usually used to represent the period of oscillation or some other specific time, while the letter ## t ## indicates a running time.
 
Charles Link said:
The letter ## A ## is usually used for area. Similarly, ## V ## usually means volume, or electrical voltage, while ## v ## means velocity. The letter ## T ## is usually used to represent the period of oscillation or some other specific time, while the letter ## t ## indicates a running time.
... and ##T##emperature.
 
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I remember a discussion I once had about the justifications of standard notations. We could write ##F=m \cdot a## as well as ##\Phi = B \cdot \aleph\,## - a Greek 'F', a Cyrillic 'W' and a Hebrew 'a'. What an incredible chaos would break lose. The discussion I mentioned was about matrices: why ##a_{ij}## and not ##a_{ji}\,?## Well, because ##a_{ji}## would be the transpose. It makes sense in a way, although there is no logical reason for it.
 
Basically, no. Different people have different rules (i.e. notation schemes), sometimes the same people use different notation in different situations. It is a problem you will have to deal with through out your career in the physical sciences. This is why it's important to help out people reading your work by making it clear what your notation means.
 
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The 'rules' are very local and they have to be different for handwritten work.
 

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