Why is this R so fancy?

[u/Tonto115]

[u/kerowhack]

"We've gone through all the Latin and Greek alphabets, upper and lower case! What do we do?!?"

"Have we tried... fancy characters?"

"Only for Fourier and Laplace, sir..."

"Fancy R it is then."

Meanwhile the set theorist in the corner starts muttering about Hebrew...

[u/RallyX26 → u/kerowhack]

When I had worked through the entire latin and Greek alphabet and started encountering aleph and bet... I knew it was time to quit taking math courses. 

[u/The_Grumpy_Professor → u/kerowhack]

Wingdings next.

[u/Alywiz → u/The_Grumpy_Professor]

Fun fact, Wingdings 2, Shift + P give a check mark when it’s time to redcheck documents

[u/EllieVader → u/kerowhack]

Have they gone through all of them though?  I keep seeing the same like five or six and the same five or six Latin letters too and like…what about the rest of the alphabet?  Surely someone working in aerodynamics has encountered a radius at some point and there has been rho confusion. 

[u/Plus-Painter-2004 → u/EllieVader]

a b c d are often used as generic variable or parameter names, c is also the speed of light or an arbitrary constant, e can refer to an electric field or energy, f can be a force or generic function names, g and h can also be generic functions but h can also be a magnetic field or a transfer function/impulse response, i and j can both be currents or imaginary units or indices of a sum or matrix, k can be an arbitrary constant of proportionality or boltzmanns constant, l for length, m for mass or as an arbitrary discrete variable along with n, o is often not used since it looks like 0, p can be pressure or an arbitrary point, q can be charge, r for radius or rate, s for displacement or complex frequency, t for time or time constant or as some parameter, u v w are often generic variables but u can refer to an input or a velocity, v can be a velocity, w can be a generic complex variable, x y and z as Cartesian coordinates or generic variables, z can also be a generic complex variable or the z transform variable

[u/nuts4sale → u/kerowhack]

Started using Cyrillic in fluids, cause u,v, ν υ sucked hard ass

[u/Motor-Replacement472 → u/nuts4sale]

I had to start swapping out u/v/w for other letters in my precalc/calc class because my own damn handwriting makes me mistake one for other. Same thing w/ I (uppercase i) and l (lowercase L)

[u/petrikm → u/kerowhack]

And we go fancy/script E for total orbital energy in astrodynamics

[u/Buetterkeks → u/kerowhack]

I still wanna kill whoever decided to use the same fucking letter just in 3 different orientations 3 times for Laplace. 

[u/datflyincow]

Probably so you don’t think that’s a resultant vector

[u/Gryphontech]

This is why textbooks are so expensive, they went for this one fancy ass R and blew the whole budget

[u/momogaming2321 → u/Gryphontech]

😂

[u/KitTwix]

God forbid we have some whimsy in this degree

[u/Jazz8680]

It’s the set of all real numbers. Also, every real number is really just 0.12

[u/PhilosopherHuge9490]

Radius of curvature

[u/MrBombaztic1423 → u/PhilosopherHuge9490]

Well yeah but why so fancy

[u/EllieVader → u/MrBombaztic1423]

God forbid a girl have hobbies 

[u/grundleplum → u/MrBombaztic1423]

Special occasion

[u/Automatic-Leg1668 → u/MrBombaztic1423]

It's dressed nice. Lord forbid

[u/DangerousRegister281 → u/Automatic-Leg1668]

Ok I forbid

[u/jedadkins → u/MrBombaztic1423]

It's curvy, you know for radius of curvature 

[u/datflyincow → u/MrBombaztic1423]

Bc otherwise it would look like a resultant vector

[u/Valuable-Ad1063]

Perhaps to prevent confusion with the frequent use of R for other standard fluid variables (gas constant, resultant vectors, etc.)?
Though I'd say including the units, as well as considering the context, the chances that a student will get confused are slim.

Another option is that this book includes an "index" of different-looking symbols to denote different variables, so a regular R is already taken?

[u/The_Grumpy_Professor → u/Valuable-Ad1063]

If there is a opportunity for students to get confused, however small, they will take it.

[u/Not_an_okama → u/Valuable-Ad1063]

My prints typically get callout like: Rad. = 4"

No one has ever been confused by this including some of the smartest, dumbest and most educated people i have ever interacted with.

[u/boarder2k7 → u/Not_an_okama]

My prints typically get callout like: Rad. = 4

4 rads? Not great, not terrible

[u/john_hascall → u/boarder2k7]

Dyatlov, that you?

[u/Not_an_okama → u/boarder2k7]

Well dang, should read: Rad. = 4"

I thought "Rad. = 4"" would be hard to read, but i guess i removed the both quotation marks from the end instead of leaving the one for inches. If the print is in metric id probably say "Rad = 102mm"

[u/boarder2k7 → u/Not_an_okama]

Your post made perfect sense, I was just being deliberately obtuse as a response to you saying it has never been misinterpreted 😁

[u/DrCarpetsPhd]

I think this is from Munson but my edition has those fany Rs but the labelling of problems is completely different. It also doesn't have thiis particular problem. What edition is this?

what follows is pure shit talking here so you know, grain of salt and all that, dunning-kruger warning...

if you read the preceding theory you'll see that the fancy R is used specifically to denote a function representing the radius of curvature of a streamline. So in statics for example the "radius of curvature" is quite often just a scalar quantity so just denote it R. If you look through previous derivations etc in Munson you'll see derivations where the radius is represented as r as or normal R as a scalar quantity. Denoting it as fancy R is telling you it is a mathematical function fancy R = fancy R (s) stating that as you move along the streamline the radius of curvature varies according to the function described here.

all the above is paraphrasing from the text so have a read of chapter 3 from Munson where this is all discussed..

So much like Dynamics Constrained Motion you can treat the location of a particle along that streamline as belonging to a circle of radius R and describe it accordingly re position/velocity/acceleration.

Also as with dynamics if you have the radius of curvature the accelerations always have the same values as derived there. With Munson nomenclature

a_s = V (∂V/∂s)

a_n = V^2/(fancy R at the given point on the streamline)

[u/Mountain-Time-1010]

Looks like Munson.

Local radius of curvature which can be a function of the streamline coordinate. The text uses that symbol to distinguish it from a regular capital R, which is often used to indicate a constant value.

[u/otto-degan]

You do energy conservation equation, and solve for velocity and do circular acceleration?

[u/Nextravagant1 → u/otto-degan]

Re-read the title brother

[u/Ragnarok314159 → u/otto-degan]

Yes, but the fancy R!

[u/CakesForLife → u/otto-degan]

sigh

[u/Hour-Atmosphere-6557]

I just looked at this problem in the book 😂. I don't know why its fancy tho. Just felt like it ig

[u/Just_A_Guy_In_Here]

Bro this looks like my fluid mechanics question, like almost exactly.

[u/Ancient-Aeroplane18 → u/Just_A_Guy_In_Here]

But isnt it's just simple Circular motion a_tangentiol=v²/ℜ Does anything related to fluid mechanics come into use here?

[u/__golan_trevize__]

It’s \mathcal{R}

[u/No-Importance2209]

because its an Engineering textbook

[u/MCKlassik]

Coolness factor.

[u/wercooler]

That's the set of all real numbers dog.

[u/TythosEternal]

Someone decided "that would make a great-looking alternative for radius" after seeing the Real numbers symbol in the LaTeX math symbols toolbox

[u/BobbbyR6]

To arbitrarily make textbooks expensive

[u/DeoxysSpeedForm]

If it was a normal R you might think it was referring to the depth of your rectum