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ImAFool · Jun 29, 2007

Only if you're name was qqwhore.

ImAFool · Jun 29, 2007

It's true.

Paris starts with a P

Ends starts with an E.

on the 19th of the last month, there was a double murder on the express train from Paris to Berlin. The engineer and the conductor were killed at the same time, even though they were at opposite ends of the train. This was confirmed by a police detective, who was at the exact center of the train and heard both gunshots at the same time.
when my cousin was told this story, he realized that both victims did not die at the same time
how did he figure it out?

--

Since it was a "double murder", one person could not be at both ends of the train. AMIRIGHT!?

full_tilt · Jun 29, 2007

50m, heard good things about him ^ XD

zack_cez · Jun 29, 2007

No....I Don't wanna kill anything and i don't have aids lol.

mage3158 · Jun 29, 2007

Who would be teh spam king me or 0120012345

devilsparadise · Jun 29, 2007

AMIRIGHT?!
no, no your not lol
well, the paris question you are

they were at both sides
there was 2 people

ok, i posted this on another forum, and some guy got the first one right

also i got a lengthy explanation on the dopplar effect and sound traveling through different substances
let me copy and paste it for you

Development
Doppler first proposed the effect in 1842 in the monograph Ãœber das farbige Licht der Doppelsterne und einige andere Gestirne des Himmels - Versuch einer das Bradleysche Theorem als integrirenden Theil in sich schliessenden allgemeineren Theorie (On the coloured light of the binary refracted stars and other celestial bodies - Attempt of a more general theory including Bradley's theorem as an integral part) [1]. The hypothesis was tested for sound waves by the Dutch scientist Christoph Hendrik Diederik Buys Ballot in 1845. He confirmed that the sound's pitch was higher as the sound source approached him, and lower as the sound source receded from him. Hippolyte Fizeau discovered independently the same phenomenon on electromagnetic waves in 1848 (in France, the effect is sometimes called "effet Doppler-Fizeau"). It is often overlooked that in Doppler's publications (and also Einstein's in his discussion of the Doppler effect) he explicitly acknowledges that his formulae are only approximate since he made several mathematical approximations in his derivation. Doppler's derivation is repeated more or less verbatim in most modern textbooks but often without the warning that the formulas are only valid in some (experimentally often seen) limits.

[edit] General
For waves that travel through a medium (sound, ultrasound, etc...) the relationship between observed frequency f' and emitted frequency f is given by:

where
is the speed of waves in the medium (in air at T degrees Celsius, this is 332 + 0.59T m/s)
is the velocity of the source (the object emitting the sound)
For waves that travel at the speed of light, such as radio waves, the relationship between observed frequency f' and emitted frequency f is given by:

Change in frequency Observed frequency

where
is the transmitted frequency
is the velocity of the transmitter relative to the receiver in meters/second: positive when moving towards one another, negative when moving away
is the speed of light in a vacuum m/s
is the wavelength of the transmitted wave subject to change
Because the detected frequency increases for objects moving toward the observer, the object's velocity must be subtracted when motion is moving toward the observer. (This is because the source's velocity is in the denominator.) Conversely, detected frequency decreases when the object moves away, and so the object's velocity is added when the motion is away. As mentioned previously this equation is only a first approximation to an exact formula, but works reasonably well in the case considered by Doppler, i.e. when the source and/or receiver moves slowly and the signal or wave moves rapidly, as well as simultaneously also being the case that the source and receiver are far apart from each other. When any of these approximations that Doppler made are violated the formulas discussed here are no longer valid except as a very rough approximation to the exact formulas.

[edit] Analysis
It is important to realize that the frequency of the sounds that the source emits does not actually change. To understand what happens, consider the following analogy. Someone throws one ball every second in a man's direction. Assume that balls travel with constant velocity. If the thrower is stationary, the man will receive one ball every second. However, if the thrower is moving towards the man, he will receive balls more frequently because the balls will be less spaced out. The converse is true if the thrower is moving away from the man. So it is actually the wavelength which is affected; as a consequence, the perceived frequency is also affected. It may also be said that the velocity of the wave remains constant whereas wavelength changes; hence frequency also changes.

If the moving source is emitting waves through a medium with an actual frequency f0, then an observer stationary relative to the medium detects waves with a frequency f given by:

which can be written as:
where v is the speed of the waves in the medium and vs, r is the speed of the source with respect to the medium (positive if moving away from the observer, negative if moving towards the observer), radial to the observer.

With a relatively slow moving source, vs, r is small in comparison to v and the equation approximates to:

A similar analysis for a moving observer and a stationary source yields the observed frequency (the observer's velocity being represented as vo):

where the same convention applies : vo is positive if the observer is moving away from the source, and negative if the observer is moving towards the source.

These can be generalized into a single equation with both the source and receiver moving. However the limitations mentioned above still apply. When the more complicated exact equation is derived without using any approximations (just assuming that everything: source, receiver, and wave or signal are moving linearly) several interesting and perhaps surprising results are found. For example, as Lord Rayleigh noted in his classic book on sound, by properly moving it is possible to hear a symphony being played backwards. This is the so-called "time reversal effect" of the Doppler effect. Other interesting cases are that the Doppler effect is time dependent in general (thus we need to know not only the source and receivers' velocities, but also their positions at a given time) and also in some circumstances it is possible to receive two signals or waves from a source (or no signal at all). In addition there are more possibilities than just the receiver approaching the signal and the receiver receding from the signal.

All these additional complications are for the classical i.e. nonrelativistic Doppler effect. However, all these results also hold for the relativistic Doppler effect as well.

The first attempt to extend Doppler's analysis to light waves was soon made by Fizeau. In fact, light waves do not require a medium to propagate and the correct understanding of the Doppler effect for light requires the use of the Special Theory of Relativity. See relativistic Doppler effect.

[edit] Applications

A stationary microphone records moving police sirens at different pitches depending on their relative direction.
[edit] Everyday
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 the observer directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit him, and then immediately jump to a new lower pitch. Because the vehicle passes by the observer, the radial velocity does not remain constant, but instead varies as a function of the angle between his 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 Â¸ is the angle between the object's forward velocity and the line of sight from the object to the observer.

[edit] Astronomy

Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to that of the Sun (left).The Doppler effect for electromagnetic waves such as light, is of great use in astronomy, and results in either a so-called redshift or blueshift. It has been used to measure the speed at which stars and galaxies are approaching toward or receding from us, that is, the radial velocity. This is used to detect if a single star is, in fact, a close binary and even to measure the speed of rotation of stars and galaxies.

The use of the Doppler effect for light in astronomy depends on the fact that the spectra of stars are not continuous. They show absorption lines at well defined frequencies that are correlated with the energies required to excite electrons in various elements from one level to another. The Doppler effect is recognizable in the fact that the absorption lines are not always at the frequencies that are obtained from the spectrum of a stationary light source. Since blue light has a higher frequency than red light, the spectral lines from an approaching astronomical light source show a blueshift and those of receding sources show a redshift.

Among the nearby stars, the largest radial velocities with respect to the Sun are +308 km/s (BD-15Â°4041, also known as LHS 52, 81.7 light-years away) and -260 km/s (Woolley 9722, also known as Wolf 1106 and LHS 64, 78.2 light-years away). Positive radial velocity means the star is receding from the Sun, negative that it is approaching.

[edit] Temperature measurement
Another use of the Doppler effect, which is found mostly in astronomy, is the estimation of the temperature of a gas which is emitting a spectral line. Due to the thermal motion of the gas, each emitter can be slightly red or blue shifted, and the net effect is a broadening of the line. This line shape is called a Doppler profile and the width of the line is proportional to the square root of the temperature of the gas, allowing the Doppler-broadened line to be used to measure the temperature of the emitting gas.

[edit] Radar
Main article: Doppler radar

The Doppler effect is also used in some forms of radar to measure the velocity of detected objects. A radar beam is fired at a moving target - a car, for example, as radar is often used by police to detect speeding motorists - as it approaches or recedes from the radar source. Each successive wave has to travel further to reach the car, before being reflected and re-detected near the source. As each wave has to move further, the gap between each wave increases, increasing the wavelength. In some situations, the radar beam is fired at the moving car as it approaches, in which case each successive wave travels a lesser distance, decreasing the wavelength. In either situation, calculations from the Doppler effect accurately determine the car's velocity.

The proximity fuze which was developed during World War II also relies on Doppler radar.

[edit] Medical imaging and blood flow measurement
An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. One of the limitations is that the ultrasound beam should be as parallel to the blood flow as possible. Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output. Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related medical measurements.

Although "Doppler" has become synonymous with "velocity measurement" in medical imaging, in many cases it is not the frequency shift (Doppler shift) of the received signal that is measured, but the phase shift (when the received signal arrives).

Velocity measurements of blood flow are also used in other fields of medical ultrasonography, such as obstetric ultrasonography and neurology. Velocity measurement of blood flow in arteries and veins based on doppler effect is an effective tool for diagnosis of vascular problems like stenosis[2].

[edit] Flow measurement
Instruments such as the laser Doppler velocimeter (LDV), and Acoustic Doppler Velocimeter (ADV) have been developed to measure velocities in a fluid flow. The LDV and ADV emit a light or acoustic beam, and measure the doppler shift in wavelengths of reflections from particles moving with the flow. The actual flow is computed as a function of the water velocity and face. This technique allows non-intrusive flow measurements, at high precision and high frequency.

[edit] Underwater Acoustics
In military applications the Doppler shift of a target is used to ascertain the speed of a submarine using both passive and active SONAR systems. As a submarine passes by a passive Sonobuoy, the stable frequencies undergo a Doppler shift and the speed and range from the Sonobuoy can be calculated. If the SONAR system is mounted on a moving ship or an another submarine, then the relative velocity can be calculated.
Click to expand...

lmao

mage3158 · Jun 29, 2007

#2
They couldn't have died at the EXACT same time because they could of
Gotten hit in two different places therefor could not die at the same time.

Close?

soccertj · Jun 29, 2007

WOOT MY 100th POST FINALLY LOLZSOZ

WinterDreamZ3 · Jun 29, 2007

ImAFool said: ↑

I saved for the iphone. Which I want to buy within the next 2 months.
Click to expand...

Cool those are really expensive.

nono5666 · Jun 29, 2007

Fucccck you

mage3158 · Jun 29, 2007

nono5666 said: ↑

Fucccck you
Click to expand...

Thank you for your flaming opinion.

Darukai-Rumone · Jun 29, 2007

Rawr.

pha que1 · Jun 29, 2007

Gotta go with WoW Blows is gay >_>

mage3158 · Jun 29, 2007

pha que1 said: ↑

Gotta go with WoW Blows is gay >_>
Click to expand...

That option is to prove once and for all.

xWcMastax · Jun 29, 2007

w0w blows is gay ftw lol just cause its funny

rooofl · Jun 29, 2007

thats hawt

Robin · Jun 29, 2007

The princess chick.

And for ImAFool: http://www.youtube.com/watch?v=sNYDpH0Jors

Elvemaqe · Jun 29, 2007

I would kill 1000 people with AIDS to cure AIDS...random clean people shouldn't die cuz of some ppl having UNSAFE fun..

Robin · Jun 29, 2007

Noooooooo

revo325 · Jun 29, 2007

This Thread Is Useless =\, Also It Doesn't Make Sense

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