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This is a question that I got wrong on an exam and I, nor my teacher who wrote it, know why it is wrong. The question involves a collision of 2 charged particles of the same charge and mass, say 2 protons initially EACH going at a constant speed of let's say 1*10^6 m/s. (I don't know the exact numbers but the exact answer is not what I'm interested in.) The question asks to find the distance between the 2 particles when they slow to a stop due to their charges. In order to solve the problem one must equate kinetic energies to the electric potential energy. I, being the genius that I am (sarcasm alert), used the relative speeds of the 2 particles (1 particle is stationary, the other moving at twice the original speed). I got an answer for distance at half the distance in the answer. I and my teacher can see mathematically why it's wrong 2(.5mv^2)is not equal to (.5m(2v)^2) but I don't understand it physically. Shouldn't the distance from the perpective of one of the particles be the same as the distance from any other perpective?
Whats the best way to stop overtone resonances in a cylindrical tube closed at one end and exicted at the other? -- Tugjob 02:32, 21 June 2007 (UTC)
Did any dinosaurs have a syrinx or even a larynx?
How is global warming related to natural disaster?
Dear 219.75.59.207, the page extreme weather, which you just vandalized, contains some information relevant to your question. -- 169.230.94.28 09:10, 21 June 2007 (UTC)
Today I went to have a test to see if I was suitable to handle food. They took swabs from my arm pits, groin region and my nose. They also requested a sample of my faeces. Does anybody know what procedures are done on the material? What do they look for and how do they identify it's presence? Bastard Soap 10:02, 21 June 2007 (UTC)
thers any one could help me to ans. these question.
A proffesor of religious studies after parking his car for 8 hours in a shed,checked the pressure and found it to be normal for the car.He then drove to another town and discovered that the pressure had slightly increased.In his wisdom,he decided to let some air out in order to reduce the pressure to its original level.comment on this action.
(*response*)He could have changed altitude or the outside temp could have changed, both of these things would change the volume/pressure of the air in the tires yet would not change the amount of air in them, so "commenting on the action" it was stupid if he has to drive back, because as soon as he goes back to the earlier conditions/ place where the pressure was normal the tires will be flat because he let air out. - Matt June 21 2007
You should tell you physics professor that it's not cool to make fun of religious studies professors Nil Einne 22:18, 23 June 2007 (UTC)
I suspect that this is a riddle whose answer is a pun. — Tamfang 04:58, 24 June 2007 (UTC)
Why is it that there is apparently only space for 400 satellites in geostationary orbit?
Thanks, --Fadders 14:54, 21 June 2007 (UTC)
Couldn't they stick them all together and create a huge ring around the earth. Then they wouldn't crash.
Many years ago Tom Digby pointed out that the number could easily be tripled if the added sats have ion engines (which provide a weak thrust steadily for years) pointed parallel to the axis; the thrust added to the gravity vector shifts the orbital plane enough to provide a few degrees of spacing. — Tamfang 05:02, 24 June 2007 (UTC)
I'm in a bit of a puzzle about the theory of relativity because of the following...
if a person was traveling 1000mph down a highway, and another person was traveling in the same direction at 100 mph
Person A
<-- (1000mph)
Person B
<-- (100 mph)
A clock would tick slower for person A right? But what i dont understand is that if this were to take place on earth, and for all intensive purposes earth was traving at around 10,000 mph in the oposite direction as the people were traveling.. then
____________
(...................)
( <--Person A )
( <--Person B )
(___________)earth --> 10,000 mph
so on earth person A is moving faster, and would be at a slower relative time, but looking at the entire picture person A is traveling 9,0000 MPH and person B is traveling at 9,900 MPH... so the clock would tick slower for person B because they are moving faster? These two ideas, yet the same situation seem to contradict eachother.
Hopefully you understand my question, its rather hard to express, but it is bothering me.
-Matt
But its not just earth that is moving at 10,000 mph, the people are too, and the people are in fact moving 9,000 and 9,900 mph, and from one perspective B is moving faster relative to A, but from another perspective A is moving faster than B. So even with your answer, In the the following (identical, yet different situations) they contradict eachother.
what would make earth so special to be the only point to which to be relative to, and not say the solar system instead. or if there was a plane flying by, why not be relative to the plane, why would they have to be relative to earth, your answer doesnt really help (and depending on what object you chose to be relative to... the answers differ) for instance you could say that Person A is traveling 9,000 mph relative to the sun, and person B is traveling 9,900 mph relative to the sun... so your answer contradicts itself in the same way as my question —Preceding unsigned comment added by Demostheness ( talk • contribs)
In this vein, there's something I've always wondered. Suppose I have a universe that's empty except for two pointlike astronauts and has the topology of a 3-sphere. They move towards each other and then synchronize their watches when they reach the same spot (from their point of view; the point here is to make everything symmetric). They then go off on their separate ways, and then meet up again. Each one can reason that the other's clock is slower, since they weren't moving and nobody underwent any acceleration, but their situation is symmetric, so their clocks will match up. How is this resolved? Veinor (talk to me) 16:17, 21 June 2007 (UTC)
Veinor, how do they meet up again if there is no acceleration? Noname
After reading the article on Graphology I am wondering whether messy or relatively difficult to read handwritting has been positively or negatively correlated with certain segments of the population. Commonly, doctors are often cited as having rather difficult to read handwritting, more so than the general population, although I have never seen any studies about the matter. Outside of of the obvious or expected (like beginning writers or calligraphers) are any segments of the population more or less prone to exhibit poor handwritting? (segments = subject of study, higher education, hobbies, gender, profession, perfectionism... etc) I would like to avoid anecdotal evidence in the answer if possible unless it is a reference to a scientific study. 128.196.125.8 22:05, 21 June 2007 (UTC)
How can bird sit on a high-voltage power line and not get electrocuted? I can't find it. - Viola sk8 1976 22:20, 21 June 2007 (UTC)
WHen you get really high voltage wires, such as over 50000 volts the electric field around the wire is very strong and you can get corona discharge from spiky bits. Birds avoid these wires. GB 03:26, 22 June 2007 (UTC)
Ok, sweet. There should be something added on Wiki to explain that...but where would it go, do you think? Oh, and thast video is pretty sweet. I'd like that job.-
Viola
sk8
1976 19:49, 22 June 2007 (UTC)
It should perhaps also be noted that this phenomenon is not limited to birds. Electric linemen under controlled conditions (i.e. while standing in insulated buckets carefully isolated from ground) can and do work on live wires bare-handed, although at higher voltages they have to take precautions to avoid capacitive inrush effects. I myself have held a bare, live, relatively low voltage (120V) wire in my mouth without ill effect, although as that was original research I suppose I shouldn't mention it here. (Oh, and the obligatory: "Don't try this at home, kids.") — Steve Summit ( talk) 00:30, 23 June 2007 (UTC)
I heard that somewhere that air pressure applied by air vortexs that are launched from a source [e.g airzooka] conform to the inverse square law [half the distance four times the effect] is this true? and if not what law does apply to them? Robin
Science desk | ||
---|---|---|
< June 20 | << May | June | Jul >> | June 22 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
This is a question that I got wrong on an exam and I, nor my teacher who wrote it, know why it is wrong. The question involves a collision of 2 charged particles of the same charge and mass, say 2 protons initially EACH going at a constant speed of let's say 1*10^6 m/s. (I don't know the exact numbers but the exact answer is not what I'm interested in.) The question asks to find the distance between the 2 particles when they slow to a stop due to their charges. In order to solve the problem one must equate kinetic energies to the electric potential energy. I, being the genius that I am (sarcasm alert), used the relative speeds of the 2 particles (1 particle is stationary, the other moving at twice the original speed). I got an answer for distance at half the distance in the answer. I and my teacher can see mathematically why it's wrong 2(.5mv^2)is not equal to (.5m(2v)^2) but I don't understand it physically. Shouldn't the distance from the perpective of one of the particles be the same as the distance from any other perpective?
Whats the best way to stop overtone resonances in a cylindrical tube closed at one end and exicted at the other? -- Tugjob 02:32, 21 June 2007 (UTC)
Did any dinosaurs have a syrinx or even a larynx?
How is global warming related to natural disaster?
Dear 219.75.59.207, the page extreme weather, which you just vandalized, contains some information relevant to your question. -- 169.230.94.28 09:10, 21 June 2007 (UTC)
Today I went to have a test to see if I was suitable to handle food. They took swabs from my arm pits, groin region and my nose. They also requested a sample of my faeces. Does anybody know what procedures are done on the material? What do they look for and how do they identify it's presence? Bastard Soap 10:02, 21 June 2007 (UTC)
thers any one could help me to ans. these question.
A proffesor of religious studies after parking his car for 8 hours in a shed,checked the pressure and found it to be normal for the car.He then drove to another town and discovered that the pressure had slightly increased.In his wisdom,he decided to let some air out in order to reduce the pressure to its original level.comment on this action.
(*response*)He could have changed altitude or the outside temp could have changed, both of these things would change the volume/pressure of the air in the tires yet would not change the amount of air in them, so "commenting on the action" it was stupid if he has to drive back, because as soon as he goes back to the earlier conditions/ place where the pressure was normal the tires will be flat because he let air out. - Matt June 21 2007
You should tell you physics professor that it's not cool to make fun of religious studies professors Nil Einne 22:18, 23 June 2007 (UTC)
I suspect that this is a riddle whose answer is a pun. — Tamfang 04:58, 24 June 2007 (UTC)
Why is it that there is apparently only space for 400 satellites in geostationary orbit?
Thanks, --Fadders 14:54, 21 June 2007 (UTC)
Couldn't they stick them all together and create a huge ring around the earth. Then they wouldn't crash.
Many years ago Tom Digby pointed out that the number could easily be tripled if the added sats have ion engines (which provide a weak thrust steadily for years) pointed parallel to the axis; the thrust added to the gravity vector shifts the orbital plane enough to provide a few degrees of spacing. — Tamfang 05:02, 24 June 2007 (UTC)
I'm in a bit of a puzzle about the theory of relativity because of the following...
if a person was traveling 1000mph down a highway, and another person was traveling in the same direction at 100 mph
Person A
<-- (1000mph)
Person B
<-- (100 mph)
A clock would tick slower for person A right? But what i dont understand is that if this were to take place on earth, and for all intensive purposes earth was traving at around 10,000 mph in the oposite direction as the people were traveling.. then
____________
(...................)
( <--Person A )
( <--Person B )
(___________)earth --> 10,000 mph
so on earth person A is moving faster, and would be at a slower relative time, but looking at the entire picture person A is traveling 9,0000 MPH and person B is traveling at 9,900 MPH... so the clock would tick slower for person B because they are moving faster? These two ideas, yet the same situation seem to contradict eachother.
Hopefully you understand my question, its rather hard to express, but it is bothering me.
-Matt
But its not just earth that is moving at 10,000 mph, the people are too, and the people are in fact moving 9,000 and 9,900 mph, and from one perspective B is moving faster relative to A, but from another perspective A is moving faster than B. So even with your answer, In the the following (identical, yet different situations) they contradict eachother.
what would make earth so special to be the only point to which to be relative to, and not say the solar system instead. or if there was a plane flying by, why not be relative to the plane, why would they have to be relative to earth, your answer doesnt really help (and depending on what object you chose to be relative to... the answers differ) for instance you could say that Person A is traveling 9,000 mph relative to the sun, and person B is traveling 9,900 mph relative to the sun... so your answer contradicts itself in the same way as my question —Preceding unsigned comment added by Demostheness ( talk • contribs)
In this vein, there's something I've always wondered. Suppose I have a universe that's empty except for two pointlike astronauts and has the topology of a 3-sphere. They move towards each other and then synchronize their watches when they reach the same spot (from their point of view; the point here is to make everything symmetric). They then go off on their separate ways, and then meet up again. Each one can reason that the other's clock is slower, since they weren't moving and nobody underwent any acceleration, but their situation is symmetric, so their clocks will match up. How is this resolved? Veinor (talk to me) 16:17, 21 June 2007 (UTC)
Veinor, how do they meet up again if there is no acceleration? Noname
After reading the article on Graphology I am wondering whether messy or relatively difficult to read handwritting has been positively or negatively correlated with certain segments of the population. Commonly, doctors are often cited as having rather difficult to read handwritting, more so than the general population, although I have never seen any studies about the matter. Outside of of the obvious or expected (like beginning writers or calligraphers) are any segments of the population more or less prone to exhibit poor handwritting? (segments = subject of study, higher education, hobbies, gender, profession, perfectionism... etc) I would like to avoid anecdotal evidence in the answer if possible unless it is a reference to a scientific study. 128.196.125.8 22:05, 21 June 2007 (UTC)
How can bird sit on a high-voltage power line and not get electrocuted? I can't find it. - Viola sk8 1976 22:20, 21 June 2007 (UTC)
WHen you get really high voltage wires, such as over 50000 volts the electric field around the wire is very strong and you can get corona discharge from spiky bits. Birds avoid these wires. GB 03:26, 22 June 2007 (UTC)
Ok, sweet. There should be something added on Wiki to explain that...but where would it go, do you think? Oh, and thast video is pretty sweet. I'd like that job.-
Viola
sk8
1976 19:49, 22 June 2007 (UTC)
It should perhaps also be noted that this phenomenon is not limited to birds. Electric linemen under controlled conditions (i.e. while standing in insulated buckets carefully isolated from ground) can and do work on live wires bare-handed, although at higher voltages they have to take precautions to avoid capacitive inrush effects. I myself have held a bare, live, relatively low voltage (120V) wire in my mouth without ill effect, although as that was original research I suppose I shouldn't mention it here. (Oh, and the obligatory: "Don't try this at home, kids.") — Steve Summit ( talk) 00:30, 23 June 2007 (UTC)
I heard that somewhere that air pressure applied by air vortexs that are launched from a source [e.g airzooka] conform to the inverse square law [half the distance four times the effect] is this true? and if not what law does apply to them? Robin