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

In summary: The reason that acceleration and velocity have mostly lower case letters is because they are seen as basic vectors, while force is seen as a more complex vector.
  • #1
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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  • #2
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.
 
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  • #3
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.
 
  • #4
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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  • #5
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.
 
  • #6
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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  • #7
The 'rules' are very local and they have to be different for handwritten work.
 

1. Why is the force vector F but acceleration vector a not A?

The force vector (F) and acceleration vector (a) are both physical quantities that describe the motion of an object. However, they represent different aspects of that motion and are measured in different units.

2. What is the difference between force vector F and acceleration vector a?

The force vector (F) is a measure of the amount of force applied to an object, while the acceleration vector (a) is a measure of how quickly the object is changing its velocity. In other words, force causes acceleration, but they are not interchangeable terms.

3. Can force and acceleration have the same direction?

Yes, force and acceleration can have the same direction. When the force applied to an object is in the same direction as its velocity, the object will experience an increase in speed (positive acceleration). When the force applied is in the opposite direction to its velocity, the object will experience a decrease in speed (negative acceleration).

4. Why is force measured in newtons (N) and acceleration measured in meters per second squared (m/s^2)?

The units for force and acceleration are based on their respective definitions. Force is defined as the product of mass and acceleration (F=ma), and the SI unit for mass is kilograms (kg) and the SI unit for acceleration is meters per second squared (m/s^2). Therefore, the unit for force is kg*m/s^2, which is equivalent to newtons (N).

5. How do force and acceleration relate to each other?

According to Newton's Second Law of Motion, the force applied to an object is directly proportional to its acceleration. This means that the greater the force applied, the greater the acceleration will be, and vice versa. Additionally, the direction of the acceleration will always be in the same direction as the net force acting on the object.

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