
#1
May304, 11:41 PM

P: 5,616

Is there a reference list anywhere where I can look for the meaning of a weird physics symbol when I run across one? For instance there is a thing that looks like a sideways capitol M. (There are two of them in the new PF banner to the right of Einstein's face.)
I ran into this sideways capitol M in one version of Hookes law: (Weird Sideways Capitol M)F = kx A different physics text gave Hookes law as F~(triangle)x The triangle, I believe, is delta, which means change, but I'm not sure what the ~ means. In both cases I understood the verbal explanations of Hookes law, which is that the restoring force is directly proportional to the amount of displacement from equilibrium. The meaning of the symbols I don't understand is, no doubt, covered in earlier chapters I haven't read. However I often look things up as background for something else I'm researching and don't have time to read the previous 300 pages to find the symbol that is baffling me. Therefore if anyone has a link to a list of these symbols and what they mean it would be a great help. Zoobyshoe 



#2
May404, 12:43 AM

Mentor
P: 7,291

Is this
[tex] \Sigma [/tex] The weird sideways M? If so that is a Greek Sigma, it is used to denote summation. In your case it would be the Sum of the Forces. 



#3
May404, 02:04 AM

Emeritus
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PF Gold
P: 10,424

The tilde, in that context, is used to indicate proportionality: F is proportional to the change in x.
It's most often shown as [tex]F \propto \Delta x[/tex] and is read as "F is proportional to the change in x."  Warren 



#4
May404, 02:30 AM

P: 5,616

Weird Physics Symbols
[tex] \Sigma [/tex]
Yes this is it. I don't understand why they would express Force that way in Hooke's law. Why "the sum of the forces" rather than just "force"? I think there is only one force at work here (simple harmonic motion): the restoring force. 



#5
May404, 02:35 AM

P: 5,616

No list of these symbols anywhere? 



#6
May404, 03:05 AM

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zooby,
It's a stupid notation in the case of Hooke's law. F is always considered to be the net force, and that's all [itex]\Sigma F[/itex] means  net force. There is no specific list of symbols anywhere, because often the symbols are dependent on context. There are many different ways or representing the same equation, with different notational systems. Unfortunately, since there is no rigorous standard, there can be no cheatsheet.  Warren 



#7
May404, 03:17 AM

P: 5,616





#8
May404, 03:22 AM

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I feel your pain  you have an excellent resource right here at pf though. Ask anything you'd like.
 Warren 



#9
May404, 08:25 AM

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#11
Aug408, 11:55 AM

P: 1

One thing I'd like to note here is about the symbol: ∝ (Greek: alpha)
This is used in mathematical functions as proportional as stated in the example you've given yet there are other uses for Greek alpha as angular acceleration, linear expansion, coefficients (sometimes), and alpha particles. It is a wonder we get anything scientifically done at all with the complete lack of standardized symbols and communication without reference. Cheers, Matthew Jordan 


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