Naked Science Forum
Non Life Sciences => Technology => Topic started by: neilep on 06/05/2016 19:09:04
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Dearest Car-Brake-Squeakologists,
As a sheepy I of course luff to drive my cars, I luff it !!
look here I am driving my motor:
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A bonafide non doctored piccy of me driving my car !!
Recently, my car has been singing to me when I brake, it;s a nice single tune of one note that sounds like a screaming cat playing a violin !
One thing I have noticed , is that the pitch/tone of the squeak does not change as the car slows down....why's that then ?
Why Does The Pitch Of My Squeaky Car Brakes Remain Constant whilst braking and slowing ?
This is a phenomenon that deserves study and an answer is beckoned from my sheepy bum heart
hugs and shmishes
mwah mwah
sheepy
xxxxx
I did ask a mouse if it would leak
The nature of my brakey squeak
But answer did not come very far
Cos i run it over in my car !!...lol (the rhymes get worse ewe know !)
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It's a mating call. Very species-specific. Ask any bird.
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I vote for resonance (https://en.wikipedia.org/wiki/Resonance).
No matter how fast a violin-string is bowed, the pitch is constant.
Also true of bowed metal, e.g. ... Bowed Metal Music (https://www.youtube.com/watch?v=ESeWcRNLnoA)* , or "singing" bowls (https://www.youtube.com/watch?v=0h7uk75-X9Q).
[ * psychological cruelty more-like [:)] ]
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does the tone change at all if you do other things differently?
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does the tone change at all if you do other things differently?
The timbre (https://en.wikipedia.org/wiki/Timbre#Harmonics) can change, with the fundamental pitch (https://en.wikipedia.org/wiki/Fundamental_frequency) remaning constant.
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The squeak comes from the drum or disk being set vibrating and the pitch is determined by the dimensions of the drum or disk.
the fundamental frequency will remain constant although the harmonic content may well vary with the degree of braking
As RD said!
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...one note that sounds like a screaming cat playing a violin !
There is a general myth that violin strings are made from the gut of cats. This is because the material is called catgut, possibly because a dancing master's violin used to be called a kit.
The strings are in fact made from the intestines of another animal. Now, what is it, had it on the tip of my tongue a moment ago, begins with s, ah I remember ........
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There might be some subtle temperature dependence for the pitch of the squeak. As has been pointed out by others, it is the physical dimensions and condition of whatever is vibrating. The speed of sound in the vibrating object (as well as its dimensions) will change ever so slightly with temperature, so one would expect this to have an effect (this is why the band has to literally "warm up" before tuning)
There might also be a way to dampen the vibration with water or oil or something to lower the pitch. Like a water gong: