How to write that per that in mathematical terms?

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Discussion Overview

The discussion revolves around how to express the phrase "this per that" in mathematical terms, particularly in the context of rates such as meters per second. Participants explore the differences between various mathematical representations, including fractions and equations, and seek clarification on the proper syntax and meaning of these expressions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant asks how to mathematically express "50 meters per 30 seconds" and whether it should be written as a fraction or an equation.
  • Another participant suggests that the expression can be written in various forms, such as fractions (e.g., 1 + 2/3 m/s, 50/30 m/s) and emphasizes that "50 m = 30 s" is incorrect because it implies equality between different units.
  • A follow-up question is posed about whether one can equate the fraction to a numerical value, such as "50 m/30 s = 5/3".
  • One participant asserts that the equation cannot be formed due to mismatched units, but offers a valid expression as "50 m/30 s = 5 m/3 s".
  • Another participant compares the grammatical structure of the expressions, arguing that "50 m = 30 s" is akin to a sentence that makes a statement, whereas "50 m/30 s" is simply a value without an equality statement.

Areas of Agreement / Disagreement

Participants express differing views on how to represent the concept mathematically, with some agreeing on the importance of unit consistency while others focus on the grammatical structure of the expressions. The discussion does not reach a consensus on the best way to express "this per that" in mathematical terms.

Contextual Notes

Participants highlight the importance of unit consistency in mathematical expressions and the distinction between expressions that imply equality versus those that represent rates. There is an ongoing exploration of how to articulate these concepts clearly in mathematical language.

Juwane
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How to write "this per that" in mathematical terms?

What is the mathematical equivalent of saying, for example, meters per second?

If we want to say that something moves with the rate of 50 meters per 30 seconds--do we write this as a fraction or as an equation, or we can write as both?

I mean what is the difference between saying "50 m/30 sec" and "50 m = 30 sec"? I'm confused.
 
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You would write:

[itex]1 + \frac{2}{3} \; \frac{m}{s}[/itex] or [itex]\frac{5}{3} \; \frac{m}{s}[/itex] or [itex]\frac{50}{30} \; \frac{m}{s}[/itex]

or in indefinite form:

[itex]1.6... \; \frac{m}{s}[/itex]

The general syntax being, "change in y over change in x":

[itex]\frac{\delta y}{\delta x}[/itex]

"50 m = 30 s" is not possible, = indicates equality, and 50 m is NOT equal to 30 s.
 
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tuoni said:
You would write:

[itex]1 + \frac{2}{3} \; \frac{m}{s}[/itex] or [itex]\frac{5}{3} \; \frac{m}{s}[/itex] or [itex]\frac{50}{30} \; \frac{m}{s}[/itex]

or in indefinite form:

[itex]1.6... \; \frac{m}{s}[/itex]

The general syntax being, "change in y over change in x":

[itex]\frac{\delta y}{\delta x}[/itex]

"50 m = 30 s" is not possible, = indicates equality, and 50 m is NOT equal to 30 s.

How can we I set the fraction to an equal something? Can I say something like:

[itex]\frac{50 m}{30 s} = \frac{5}{3}[/itex]
 


You cannot. Since the units don't match on each side of your equation, the equation is nonphysical.

You can say [tex]\frac{50m}{30s}=\frac{5m}{3s}[/tex]
 


Juwane said:
I mean what is the difference between saying "50 m/30 sec" and "50 m = 30 sec"? I'm confused.

Compare these two sentences.

"The man walked over the hill."

"The man with no hair."

The first one is a sentence. The second isn't.

The same is true of "50m = 30sec" and "50 m/30 sec". The equals sign makes a statement about two values. It says the value on the left is equal to the value on the right. The second one is just a value... with no equals sign. The equals sign is the verb. Without one, you just have a meaningless noun.

What you want to express can't be put into symbols. Use words to describe it: "the man ran 50m in 30sec" or "His velocity was 50m/30sec".
 
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