How to write that per that in mathematical terms?

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The discussion focuses on how to express "this per that" in mathematical terms, specifically using the example of meters per second. It clarifies that "50 m/30 sec" represents a rate, while "50 m = 30 sec" is incorrect because it implies equality between two different units. The correct way to express the rate is through fractions, such as "50 m/30 s" or "5/3 m/s." The conversation emphasizes that without an equals sign, the expression is not a complete statement, and suggests using descriptive language to convey the intended meaning. Ultimately, the distinction between rates and equalities is crucial for accurate mathematical communication.
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:

1 + \frac{2}{3} \; \frac{m}{s} or \frac{5}{3} \; \frac{m}{s} or \frac{50}{30} \; \frac{m}{s}

or in indefinite form:

1.6... \; \frac{m}{s}

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

\frac{\delta y}{\delta x}

"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:

1 + \frac{2}{3} \; \frac{m}{s} or \frac{5}{3} \; \frac{m}{s} or \frac{50}{30} \; \frac{m}{s}

or in indefinite form:

1.6... \; \frac{m}{s}

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

\frac{\delta y}{\delta x}

"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:

\frac{50 m}{30 s} = \frac{5}{3}
 


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

You can say \frac{50m}{30s}=\frac{5m}{3s}
 


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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Here is a little puzzle from the book 100 Geometric Games by Pierre Berloquin. The side of a small square is one meter long and the side of a larger square one and a half meters long. One vertex of the large square is at the center of the small square. The side of the large square cuts two sides of the small square into one- third parts and two-thirds parts. What is the area where the squares overlap?

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