Undergrad How does pi in physics relate to circular motion and waves?

[NoahOl]

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

edit: [Link Spam edit deleted by the Mentors, and spammer OP has been banned][/ b]

 

[A.T.]

 

[PeroK]

I'm more of a tau man, myself.

 

[Ibix]

Taking the daft question seriously, $\pi$ (or $\tau/2$, to appease PeroK) appears in our mathematical models, usually through trigonometry or trigonometric functions in the solutions of differential equations. Whether it appears in reality (or whether that statement even makes sense) is in the realm of philosophy and is largely "who cares" as long as the models make accurate predictions. We can worry about whether the $\pi$s should appear exactly when models start making inaccurate predictions traceable to the use of $\pi$.

 

[Ibix]

Side note: if you cut $\pi$ in two you get $\tau\tau$, but $\tau=2\pi$. There's clearly something wrong with the world.

 

[Baluncore]

Welcome to PF.

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

Written on the side of the elephant is; ω = 2⋅π⋅f

 

[fresh_42]

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

I don't know what improves engineering is meant to be. Engineers calculate and need finite approximations for $\pi .$ Improvement is at most a matter of how many valid digits are used and is subject to quite a few engineering jokes. A famous connection between $\pi$ and the real world is Buffon's needle problem. It connects measurement and $\pi .$

As @Ibix has already mentioned, $\pi$ usually enters the formulas via trig functions, e.g. the harmonic oscillator. The real world is modeled by differential equations, e.g. $y''+y=0$ with trig functions as solutions. This point of view automatically generates the presence of $e$ and by Euler's formula $e^{ ix }=\cos(x)+ i \sin(x) ,$ we are back at trig functions. Trig functions relate angles with lengths and therewith circles and waves with lengths. All quantities that matter if you describe motions.

 

[pinball1970]

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

Is this a bit of a spoof post? If it is not then as stated above pi is all over the map in physics.
In terms of engineering, if you wanted to calculate an area to your circular or elliptical base how would you do that? Or calculate the volume of your cylindrical/spherical/conical vessel?

 

[pinball1970]

How does pi in physics relate to circular motion

Could be a lost in translation thing.

 

[kuruman]

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

Watch this video. Understanding anything, not just $\pi$, improves engineering.

 

[kuruman]

Is this a bit of a spoof post? If it is not then as stated above pi is all over the map in physics.

I do not think it is a spoof. When I taught intro physics, I showed a simulation similar to the video shown above to make the connection between the period in circular motion and simple harmonic motion. Regardless of whether "pi is all over the map in physics", the question to explore here is "in what sense is something going around in a circle at constant speed related to something bobbing up and down in a straight line with varying acceleration?"

 

[Lnewqban]

Wel

How does pi in physics relate to circular motion and waves? never saw a real life example where understanding pi improves engineering...

Welcome!

For engineering practices, knowing a practical value of π is very useful each time that you have any kind of wheel rolling over a flat surface (rack and pinion mechanism, for example), or when you need to wrap a line or a plane over a round shape (building a cylindrical tank out of sheet metal, for example).

You can always roll one thing over the other and mark before cutting, but is easier and cleaner to calculate πD²/4 or πD before marking and cutting.

The practical imprecisions of fabricating parts will always eclipse any excessive precision of the value that you use, reason for which using 3.1416 is more than enough.

 

[berkeman]

Taking the daft question seriously,

Turns out it was a daft question because it was a spam setup post. OP subsequently went back and edited his post to add "link spam" into his OP. He has been banned now, and the link has been redacted. Have a nice day.

 

[kuruman]

Turns out it was a daft question because it was a spam setup post. OP subsequently went back and edited his post to add "link spam" into his OP. He has been banned now, and the link has been redacted. Have a nice day.

What exactly does a "link spam" do? I am naive in such things.

Thanks for being vigilant.

 

[berkeman]

What exactly does a "link spam" do? I am naive in such things.

Link spam means when a spam URL is hidden in a post, or when it is added back in later. In this case, the OP didn't really try to hide the URL, and just added it back in as an edit (so easy to spot as long as we were monitoring them for any subsequent activity after their OP). More well-hidden link spam is where they include the URL as a link with a different title so it is less obvious that it is an edit. Like they replace some word in their post with the same word linked to a URL. The only hint is that the word changes to a blue color since it is a link. In the worst case I've seen a period at the end of a sentence linked to a spam URL. That is almost impossible to spot, unless we do an EDIT of the post to look for the URL construct.

Apparently for some spam "artists", they get credit for placing the spam based on web crawler bots finding it, and for how long the link stays posted before being spotted and deleted. Sheesh.

EDIT/ADD: The "daft" nature of the OP question plus the location in the world of the OP (which we can see as Mentors) made this newbie a very suspicious member. That is why we were keeping a closer eye on them.

 

[kuruman]

Thank you, @berkeman, for a most informative reply. I have one more question. From your experience, are the spam links usually of the malicious kind that one shouldn't unwittingly click on?

 

[berkeman]

From your experience, are the spam links usually of the malicious kind that one shouldn't unwittingly click on?

Good question. At least for the last few years, malicious links do not seem to make it past the PF AI software. The links that I've seen have only been advertising.