The Natural Frequency of Soup!

[Awezing]

I have found that everybody who stirs soup, does so at the natural frequency of the given pot of soup. If you stir a pot of soup at its natural frequency, then the surface of the soup will rock back and forth, and will do so more violently until the longer you keep stirring at that speed. If you slow down or speed up your soup stirring, then the surface will become calm again, and stay level with the floor. However, if you exactly double or halve your speed, all you are doing is moving up or down an 'octave' and it will continue to rock back and forth. This isn't quite as interesting as using natural frequency to say, destroy buildings or planets or whatnot, but its a little more common place.

what weirds me out is that people will always gravitate the natural frequency of whatever they are stirring.


anways, this is somewhat useless and dumb, but i'm bored and figured people might want to know about the natural frequency of soup? maybe? I was gonna post this in the science section, but i don't know if its significantly science-y enough.

ps - since soup stirring doesn't really require its own thread, any other crazy things that you've noticed that people do? another example: in a large crowd, when booing somebody or something else negative, people will always do so at a decending minor third (like chanting somebody's name at a sports game to psych them out... generally works best with two syllable words)

[Alcari]

I think people stir at the natural frequenty because it works.
Then again, stirring just into the flow would mix it far better...hmmm....

This reminds me of the time my old 'highschool' class would just line up infront of the a side door to the local library. This didn't actually lead anywhere, but other people did join the line. Especially when we started "moving forward." It works even better when you get some people to look up at a building and point at it. people WILL stop and look.

Ahh, human herding. Gotta love it.

[4=5]

well I actually HUM at the natural frequency of soup or the room I'm in or whatever, it's fun because it bugs the hell out of my parents

soup is stirred at the natural frequency because that is how you get the most action, instead of hitting against yourself, you reinforce your previous action

what I'd really love to do is arrange my lawn ornaments in the shape of a elipse so that at certain speeds a car emits sound at one focus which it then catches at the other focus

Please check your posts for typos before submitting. If you want the extra help, firefox has a built in spell checker.

-Anonymod

[Alcari]

how can you hum at the natural frequenty of the room?
How do you even KNOW that? If you do know, isn't the frequenty of the room likely to be something around <10hz?

[Woxor]

Actually, I always reverse stirring direction (clockwise-counterclockwise) periodically, because I figure that turbulence helps the convection or the mixing. I don't know if that's true, but it seems true. At any rate, it keeps the natural frequency thing from spilling it.

[4=5]

how can you hum at the natural frequenty of the room?
How do you even KNOW that? If you do know, isn't the frequenty of the room likely to be something around <10hz?

the whole room is too big to hear if I'm resonet, but any alcove I can either find the main or harmonic frequency, or the tub too,

I also enjoy hetrodyneing my whisles
I taught my sibling how to also so it's fun to harmonise our hetrodyeing so it sounds really wierd

[SpitValve]

well I actualy HUM at the natrual frequency of soup or the room I'm in or wht ever, it' funn'cause it bugs the hell out of my parents

I recall one situation when people were talking naturally and every now and again the room would reverberate as somebody accidentally hit the natural frequency... it got annoying enough that I opened the door to change the harmonics

[Marbas]

I like making my plates and silverware vibrate by humming near them. It is fun. Conveniently, it makes my sister very uncomfortable because it "weirds her out".

[davef]

A house I used to live in had a little arch lust outside the front door. If you stood directly under the apex and spoke you heard the sound bouncing off the wall to your left and right simultaneously so you got this great stereo delay.

Finding resonant harmonics is usually pretty easy in a room with wood floors, or the bathroom if it's tiled.

I really hate it when people clap on the wrong beat at a concert. The accents are on the two and four, people!!

s/Lust/Just/ ?

Pfft, it staying.

-4d.

[Thunderbird4!]

I think people stir at the natural frequenty because it works.
Then again, stirring just into the flow would mix it far better...hmmm....

This reminds me of the time my old 'highschool' class would just line up infront of the a side door to the local library. This didn't actually lead anywhere, but other people did join the line. Especially when we started "moving forward." It works even better when you get some people to look up at a building and point at it. people WILL stop and look.

Ahh, human herding. Gotta love it.

Yes, I'm not the only one who does this! Though my personal favorite is in between classes to get to the class first, pull the door closed quietly while the teacher is in the room (our doors are behind the teachers) and then stand outside and tell everyone that the door is locked and when people tell me to try to turn the handle I try but intentionally fail.

[davef]

Who remembers the Radiohead video where there's a guy in a suit lying on the ground? Passers-by ask him what he's doing and he refuses to tell anyone. At the end of the video he relents, and the last shot is this amazing ascending aerial shot of dozens of people all lying on the footpath.

[hermaj]

Ummmm. Was that Just? Admittedly it's the only one I've seen and that was a long tme ago, but what you're saying seems to ring a bell.

Anyway, getting back on topic, my theory is that people stir at the natural frequency of soup because they like to see that something is happening and they think it's working better. In my very humble and absolutely non-physics-based opinion it would do less, because everything would just flow around without really mixing up too much. I tend to stir soup in a quick couple of S-motions, anyway, before it goes back in the microwave.

[davef]

I tend to stir soup in a quick couple of S-motions, anyway, before it goes back in the microwave.

Think you're right about Just.

Stirrage for me is usually figure-of-eight. (I won't microwave soup anymore since a recent unpleasant episode.) I suppose I do it because I think I'm achieving maximum displacement or movement or something.

[Vogt]

Yeah, it was Just. Recently watched that video, very interesting :].

By the way, how did you guys come upon this knowledge? Random experience or something? I'd very much like to learn something like this, haha. ^.^

[Sandry]

I think we had some music stands whose resonant frequency was actually the D above concert A. As you can imagine, this is the sort of thing one finds out really quickly. Unfortunately, tuning to your music stand does not guarantee actual good intonation.

Anyone know of any "god spots" close to their home/work/school/whatever? (This is a term I think a friend of mine made up, and is a little hard to explain. Generally happens when you've got an arc surrounding you, as in a stadium, or this one round classroom I had, and when you're at the precise right point in the room, anything you sing/speak/whistle/whatever sounds directly in your ear.) MIT has an outdoor amphitheatre that's got a good one. It totally qualifies as my idea of fun to end up over there and start singing random stupidity. Possibly I need to get out more.

[davef]

MIT has an outdoor amphitheatre that's got a good one. It totally qualifies as my idea of fun to end up over there and start singing random stupidity. Possibly I need to get out more.

Ooh, I want to do that, too! I mentioned this in an earlier post -

A house I used to live in had a little arch just outside the front door. If you stood directly under the apex and spoke you heard the sound bouncing off the wall to your left and right simultaneously so you got this great stereo delay.

but an amphitheater would be much more fun.

[4=5]

Ummmm. Was that Just? Admittedly it's the only one I've seen and that was a long tme ago, but what you're saying seems to ring a bell.

Anyway, getting back on topic, my theory is that people stir at the natural frequency of soup because they like to see that something is happening and they think it's working better. In my very humble and absolutely non-physics-based opinion it would do less, because everything would just flow around without really mixing up too much. I tend to stir soup in a quick couple of S-motions, anyway, before it goes back in the microwave.

wait you mean you stir soup to mix it not to make a votex that seperates out the materials?

[SpitValve]

I really hate it when people clap on the wrong beat at a concert. The accents are on the two and four, people!!

Yes! I find it particularly annoying when people clap every beat.

Apparently in country music it's right to clap on 1 and 3.

[xooll]

Finding resonant frequencies of a room is really fun. It's kind of hard if the room isn't fairly boxy with hard walls and floors, though. It works best in shower stalls.
Also:
http://www.aleph.se/andart/archives/200 ... iptic.html

[bbctol]

Apparently in country music it's right to clap on 1 and 3.

As well as... classical...

Hey, I just realized I missed my thousandth post!

[SpitValve]

Apparently in country music it's right to clap on 1 and 3.

As well as... classical...

But do you normally clap in classical music?

[bbctol]

Oh. Yeah. Heh heh.

Well, I sometimes do...

[hermaj]

I was under the impression that a lot of classical music does not actually have a beat, this is why it is so good to study to.

[Sandry]

Erm. Most classical has a beat, though it's not always very obvious.

Modern stuff can have totally free rhythm... I seldom find it good to study to, though, as I think an easily identifiable beat is more comforting than a mental searching for a beat which may or may not be there.

[Blatm]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

[ICDB]

I was playing a song the other day that alternated between 4/8 and 5/8. It was pretty BA.

[lanicita]

I was under the impression that a lot of classical music does not actually have a beat, this is why it is so good to study to.

This is why I study to live music... it doesn't tend to stay on the beat because they switch it up.

[TheTankengine]

I believe this exact conversation has taken place with the subject of "coffee". Anyone else remember that? I guess I'm talking to the hardcore old-skool still among us.

[3.14159265...]

When I stir tea or coffee, I make sure I DON"T stir at the natural frequency, I did take note of this and it is usefull.

If its rocking too much I just speed up a bit or slow down, and it stops getting my pants brown

[SpitValve]

I believe this exact conversation has taken place with the subject of "coffee". Anyone else remember that? I guess I'm talking to the hardcore old-skool still among us.

Not quite the same: that was talking about walking down the corridor and amplifying the oscillations until you spilt your coffee.

But yeah, same gist.

[Jakell]

I think people stir at the resonant frequency because it's easiest. If you stir faster or slower, the energy gets dumped into the resonant frequency and you waste energy maintaining the offbeat. I've often done the same while washing dishes in deep water. I have to make it a point to stir off-beat, soas not to make a big easily-cleanable mess.

I stir soup in a (hopefully) unique fashion. Instead of a figure eight, I move each loop around by about 20 degrees, and every third swirl is a vertical loop, down the outside and up the middle. It works well for me.

SpitValve wrote:

...walking down the corridor and amplifying the oscillations until you spilt your coffee.

I sometimes try to get people to speed up/slow down to get this to happen. So far no luck...

[Gelsamel]

Figure Eight? I just stir in a circle.

[damienthebloody]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

Totally. Second best thing at death metal concerts is watching people work out how to mosh to something in 5 or 7 or worse. The best thing is when you see someone who can actually do it.

[Gelsamel]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

Totally. Second best thing at death metal concerts is watching people work out how to mosh to something in 5 or 7 or worse. The best thing is when you see someone who can actually do it.

I'd just give up and stand around...

How would you even do this:

4/4 -> 7/8 -> 3/4 -> 13/16 -> 15/16 -> 17/16 -> 14/16 -> 5/4 -> 6/8 -> 2/4 -> 5/8 -> 11/4 -> 9/4 -> 7/16 -> 6/16 -> 5/16 -> 10/16 -> 9/8 -> 15/8 -> 12/16 -> 16/16 -> 3/8

[xooll]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

Totally. Second best thing at death metal concerts is watching people work out how to mosh to something in 5 or 7 or worse. The best thing is when you see someone who can actually do it.

Headbanging is extremely difficult for death metal, and in very packed crowds, being off beat can be dangerous (I once split my lip on the back of a guy's head because one of us missed a time change)

[evilbeanfiend]

....
anways, this is somewhat useless and dumb, but i'm bored and figured people might want to know about the natural frequency of soup? maybe? I was gonna post this in the science section, but i don't know if its significantly science-y enough.

o its definetly sciencey enough given its all about standing waves.

ok to answer the question:

first what we are really talking about is standing waves in the bowl/pot so we want to estimate the wave lengths a typical bowl/pot can sustain

so assuming a 0.2 m wide bowl, the lowest harmonic supported would be a 0.4 m wave. integer fractions of 0.4 cm will also work.

to work out the frequency we use f = v/l which means we need to estimate the velocity of waves in the soup. assuming the soup is a thin consume it is going to be very close to water, a bit of googling has given me a typical velocity of about 0.2 ms^-1. so given that our minimum frequency is 0.4/0.2 = 2 hertz with harmonics at integer multiples

edit: obviously a thicker soup will have slower wave velocity and .'. lower frequencies, the wavelengths should be the same for the same bowl though.

[gmalivuk]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

3/4 isn't too hard if you just clap on the downbeat.

One of the (several) reasons I really like Tool (their name is not one of the reasons, btw) is their propensity for uncommon meters. I think 11 and 13 are my favorites. Part of "Schism" has a 27-beat cycle (could actually be written as 9/4 in triplets, but that's not the point).

"Tubular Bells" (aka the Exorcist theme) starts out alternating between 7 and 8, or stays in 15, depending on your perspective.

[Azrael]

Don't forget heavy metal. Well it's not so much that it's appropriate to clap on the 1 and 3, it's just that no one really cares. What I really get a kick out of is having people try to clap along with a song in 3/4 or 5/4 (or Money by Pink Floyd, which is in 7/8.)

3/4 isn't too hard if you just clap on the downbeat.

One of the (several) reasons I really like Tool (their name is not one of the reasons, btw) is their propensity for uncommon meters. I think 11 and 13 are my favorites. Part of "Schism" has a 27-beat cycle (could actually be written as 9/4 in triplets, but that's not the point).

"Tubular Bells" (aka the Exorcist theme) starts out alternating between 7 and 8, or stays in 15, depending on your perspective.

Recently, while in Florida, I hear a lounge band play Take 5 in straight time.

I cried.

[gmalivuk]

Recently, while in Florida, I hear a lounge band play Take 5 in straight time.

I cried.

Blasphemy!

Though I do like the Emerson Lake and Palmer injection of part of Blue Rondo alla Turk in straight time (I forget which song/album it's on atm...)

If it makes you feel better, my high school's choir once sang a version of "Deck the Halls" in 7/8 time. It was part of a skit where something had been spilled on the score, removing one beat from each measure.

[Spaz Funbag]

Resonant spots can be found in many small confinements (right word?), like sowers, small bathrooms or narrow staircases.

By the way, this is the reason (according tio what my physics teacher once told us) why men sing in the shower. The shower's resonant frequency is around a level that is near a man's "comfy spot" concerning sound waves. So by humming, one is submerged in a surround sound experience that "just feels good" (and is way better thatn THX!).