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khyber
Joined: 16 Jan 2003
Location: Compunction Junction
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 Posted: Thu Apr 20, 2006 4:55 pm Post subject: questions about stupid s#!)t |
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I have a couple questions i don't get:
1) Why is it that if you drink cold water, it feels MUCH COLDER in your mouth if you drink if faster?
2) Why is it that ambulance sirens seem to change pitch as the approach you and as they drive behind you?
answers?
more questions? |
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Tiberious aka Sparkles
Joined: 23 Jan 2003
Location: I'm one cool cat!
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| Posted: Thu Apr 20, 2006 4:59 pm Post subject: |
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What are the blank pages at the back of most paperback books for?
Sparkles*_* |
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ilovebdt
Joined: 03 Jun 2005
Location: Nr Seoul
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| Posted: Thu Apr 20, 2006 5:08 pm Post subject: |
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| Why is it that when I photocopy there is always a rogue blank piece of paper in with the copies? |
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Bronski
Joined: 17 Apr 2006
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| Posted: Thu Apr 20, 2006 5:12 pm Post subject: Re: questions about stupid s#!)t |
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| khyber wrote: |
I have a couple questions i don't get:
1) Why is it that if you drink cold water, it feels MUCH COLDER in your mouth if you drink if faster?
2) Why is it that ambulance sirens seem to change pitch as the approach you and as they drive behind you?
answers?
more questions? |
1) It probably has to do with your mouth adjusting to the temperature. Like if you ease into a hot tub it won't feel as hot as if you jump in.
2) That's called the Doppler Effect: http://en.wikipedia.org/wiki/Doppler_effect
| Quote: |
The siren on a passing emergency vehicle will start out higher than its stationary pitch, slide down as it passes, and continue lower than its stationary pitch as it recedes from the observer. Astronomer John Dobson explained the effect thus:
"The reason the siren slides is because it doesn't hit you."
In other words, if the siren approached you directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit you, and then immediately jump to a new lower pitch. The difference between the higher pitch and rest pitch would be the same as the lower pitch and rest pitch. Because the vehicle passes by you, the radial velocity does not remain constant, but instead varies as a function of the angle between your line of sight and the siren's velocity:
where vs is the velocity of the object (source of waves) with respect to the medium, and �� is the angle between the object's forward velocity and the line of sight from the object to the observer. |
I don't entirely understand it, but I know that it happens. You can notice it with regular vehicles passing as well, but it's not as obvious. |
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Ya-ta Boy
Joined: 16 Jan 2003
Location: Established in 1994
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| Posted: Thu Apr 20, 2006 5:25 pm Post subject: |
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| If it is really cold and you have to ride a scooter, will you lose more body heat and feel colder if you go slow and take longer, or go fast and create a stronger wind chill factor? |
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khyber
Joined: 16 Jan 2003
Location: Compunction Junction
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| Posted: Thu Apr 20, 2006 5:27 pm Post subject: |
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so if i were to play a note on a violin say, while riding a bike...the pitch of that note would appear to change to someone as i passed them?
This is true of any sound??? |
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peppermint
Joined: 13 May 2003
Location: traversing the minefields of caddishness.
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| Posted: Thu Apr 20, 2006 5:48 pm Post subject: |
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| yeah, didn't take high school physics huh? |
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huffdaddy
Joined: 25 Nov 2005
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| Posted: Thu Apr 20, 2006 7:21 pm Post subject: |
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| khyber wrote: |
so if i were to play a note on a violin say, while riding a bike...the pitch of that note would appear to change to someone as i passed them?
This is true of any sound??? |
This is true of any wave (eg light, but things just don't move fast enough for it to be perceptable). |
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midgic
Joined: 14 Feb 2004
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| Posted: Thu Apr 20, 2006 8:35 pm Post subject: |
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| Quote: |
This is true of any wave (eg light, but things just don't move fast enough for it to be perceptable).
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One can see examples with light, too. As galaxies are flying apart from each other, the light reaching the Earth is red-shifted, (i.e. appearing to our eye to be of longer wave-length). |
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huffdaddy
Joined: 25 Nov 2005
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| Posted: Fri Apr 21, 2006 3:23 am Post subject: |
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| midgic wrote: |
| Quote: |
This is true of any wave (eg light, but things just don't move fast enough for it to be perceptable).
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One can see examples with light, too. As galaxies are flying apart from each other, the light reaching the Earth is red-shifted, (i.e. appearing to our eye to be of longer wave-length). |
Yes, but it's not something the average person notices. Unlike sound doppler. |
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Porter_Goss
Joined: 26 Mar 2006
Location: The Wrong Side of Right
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| Posted: Fri Apr 21, 2006 7:34 am Post subject: |
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| Tiberious aka Sparkles wrote: |
What are the blank pages at the back of most paperback books for?
Sparkles*_* |
Note taking and drawing pornographic pit-chas as your waygookin monkey dances. |
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elynnor
Joined: 08 Feb 2006
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| Posted: Fri Apr 21, 2006 3:52 pm Post subject: |
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...
Last edited by elynnor on Sat Oct 07, 2006 4:57 am; edited 1 time in total |
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tzechuk
Joined: 20 Dec 2004
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| Posted: Fri Apr 21, 2006 6:04 pm Post subject: Re: questions about stupid s#!)t |
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| Bronski wrote: |
| khyber wrote: |
I have a couple questions i don't get:
1) Why is it that if you drink cold water, it feels MUCH COLDER in your mouth if you drink if faster?
2) Why is it that ambulance sirens seem to change pitch as the approach you and as they drive behind you?
answers?
more questions? |
1) It probably has to do with your mouth adjusting to the temperature. Like if you ease into a hot tub it won't feel as hot as if you jump in.
2) That's called the Doppler Effect: http://en.wikipedia.org/wiki/Doppler_effect
| Quote: |
The siren on a passing emergency vehicle will start out higher than its stationary pitch, slide down as it passes, and continue lower than its stationary pitch as it recedes from the observer. Astronomer John Dobson explained the effect thus:
"The reason the siren slides is because it doesn't hit you."
In other words, if the siren approached you directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit you, and then immediately jump to a new lower pitch. The difference between the higher pitch and rest pitch would be the same as the lower pitch and rest pitch. Because the vehicle passes by you, the radial velocity does not remain constant, but instead varies as a function of the angle between your line of sight and the siren's velocity:
where vs is the velocity of the object (source of waves) with respect to the medium, and �� is the angle between the object's forward velocity and the line of sight from the object to the observer. |
I don't entirely understand it, but I know that it happens. You can notice it with regular vehicles passing as well, but it's not as obvious. |
Might be easier to explain it that sound waves change frequency depending on the distance. So if it is far from you, it is one sound; it is is close to you, it is another. Then when it moves away from you, the frequency changes again, so you hear a different sound again.
That's the nutshell of the doppler effect. |
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doggyji
Joined: 21 Feb 2006
Location: Toronto - Hamilton - Vineland - St. Catherines
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| Posted: Fri Apr 21, 2006 6:53 pm Post subject: Re: questions about stupid s#!)t |
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| tzechuk wrote: |
| Bronski wrote: |
| khyber wrote: |
I have a couple questions i don't get:
1) Why is it that if you drink cold water, it feels MUCH COLDER in your mouth if you drink if faster?
2) Why is it that ambulance sirens seem to change pitch as the approach you and as they drive behind you?
answers?
more questions? |
1) It probably has to do with your mouth adjusting to the temperature. Like if you ease into a hot tub it won't feel as hot as if you jump in.
2) That's called the Doppler Effect: http://en.wikipedia.org/wiki/Doppler_effect
| Quote: |
The siren on a passing emergency vehicle will start out higher than its stationary pitch, slide down as it passes, and continue lower than its stationary pitch as it recedes from the observer. Astronomer John Dobson explained the effect thus:
"The reason the siren slides is because it doesn't hit you."
In other words, if the siren approached you directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit you, and then immediately jump to a new lower pitch. The difference between the higher pitch and rest pitch would be the same as the lower pitch and rest pitch. Because the vehicle passes by you, the radial velocity does not remain constant, but instead varies as a function of the angle between your line of sight and the siren's velocity:
where vs is the velocity of the object (source of waves) with respect to the medium, and �� is the angle between the object's forward velocity and the line of sight from the object to the observer. |
I don't entirely understand it, but I know that it happens. You can notice it with regular vehicles passing as well, but it's not as obvious. |
Might be easier to explain it that sound waves change frequency depending on the distance. So if it is far from you, it is one sound; it is is close to you, it is another. Then when it moves away from you, the frequency changes again, so you hear a different sound again.
That's the nutshell of the doppler effect. |
From my understanding, as long as the sound source is the same, the sound wave's intrinsic frequency remains unchanged. It's all about how you get it in a "relative motion." It happens because it's moving. There are sirens A and B. Both of them have the same frequency, 100Hz. Now A is moving towards you from distance and B is stationary 10 meters away from you. Of course, you get the same 100Hz from B(just a bit less amplitude due to dissipations/damping) because there's no relative motion. You and siren B are in the same inertial frame. And imagine the moment when A exactly passes the point where B is placed. Same distance, same sound source but you don't get 100Hz in your ears. It's not like at this distance it has this unique frequency. The motion relative to you is the key. |
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noelinkorea
Joined: 09 Apr 2003
Location: Shinchon, Seoul
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| Posted: Sat Apr 22, 2006 1:23 am Post subject: wait... |
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AND why why why do Korean firemen have orange fireman suits?? To match the flames?
AND why do the police always have their lights going...'cos they watched the Dukes of Hazzard too much?? |
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