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## Re: Curve fitting units

What is Alvaro trying to say?

Is cycle=Hz*sec wrong?

I checked out Mathcad Prime results with my casio calculator, and then checked the casio calculator results with my Aristo Scholar slide rule, and they all agree

## Re: Curve fitting units

I tend to agree that the statement 'cycle=Hz*s' is wrong. Cycle is (should be) just a number without units (hence it is 1) because it is an occurrence of something...or anything. You can compare 'cycle' with e.g. 'drops of water falling' from a dripping tap. When the circumstances are unchanged, these drops fall with a certain frequency, or a period of time between them. But that does not make 'drops of water falling' a unit. It's their rate of falling that has a unit: Hz.

Mathcad allows you to define cycle as a unit.

If you do, for the above reason, define it as cycle:=1, not as cycle:=Hz*s.

Success!
Luc

## Re: Curve fitting units

So N = 100,000 what?

## Re: Curve fitting units

N=100 000 times the occurrence of one cycle if you will.

Look up the definition of rad and sr in table 3 of the SI brochure at https://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf .

There are more units that are...just 1.

Success!
Luc

## Re: Curve fitting units

wrote:

I tend to agree that the statement 'cycle=Hz*s' is wrong. Cycle is (should be) just a number without units (hence it is 1) because it is an occurrence of something...or anything. You can compare 'cycle' with e.g. 'drops of water falling' from a dripping tap. When the circumstances are unchanged, these drops fall with a certain frequency, or a period of time between them. But that does not make 'drops of water falling' a unit. It's their rate of falling that has a unit: Hz.

Mathcad allows you to define cycle as a unit.

If you do, for the above reason, define it as cycle:=1, not as cycle:=Hz*s.

Success!
Luc

I'd like to point out that Hz sec is (at least in Mathcad) unity.  So you're both right

This horse is no longer breathing, lifeless and bleeding on the floor.  Stop beating him!

## Re: Curve fitting units

I'm, as electromechanical, always use mass basis for thermodynamics, and see molar basis as a simple curiosity. But working between chemicals engineers, must to use it, even at the first understand nothing. Later I see that for chemicals the weight isn't that important, it is more important the quantity of particles, because the reactions are between them, not mases. And, for example, the hydrogen have a very little mass, and in practical calculus it mass disappear in the approximations. But taking their number (moles) in the reactors you get more accurate precision with the less effort.

If I cook bread I know that 2 kg of eggs with 10 kg of flour give me 12 kg of bread plus some humidity (it's an open system for the water). But for a chemical engineer, they use kgmol, and the product isn't the summation of the kgmol. You must to convert they first to kg. So, for things you must to be very clear about the domain of what you are adding. In mathcad for solve problems from the viewpoint of the chemistry I define kgmW, kgmH2O, kgmCl, etc for each compound as the molecular weight  for a supply for steel working with mases, not amount of things.

So, my conclusion of cycles is that it must to be very important. There are a lot of examples where the number of cycles are counting in distinct way at each region. For example, the number of passes in a heat exchange is used for calculus in some places, but in others is the number of "U" 's. It's easy get confusing counting those things. In some places people says "nos vemos en 8 días" (we'll see in 8 days) meaning "say next week". What means "we'll see in 8 days"? A week? That's don't agree my circadian cycle ...

Best regards.

Alvaro.

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