I went with speed of sound. Any idea how to figure it?

-edit-
Removed my attempt at figuring the distance for a more interesting video of the volcano erupting

shock waves are not limited to the speed of sound though right.. how did you figure it

Good example of why rail guns that fire projectiles at 7x the speed of sound are so effective. It's as if the energy of impact had something to do with velocity. I bet there's an equation for that.

>> ^Tokoki:

Woah...mind blown (twice). I mean, I knew that light was slower in air, but ~1M m/s slower? Crazy...
And the "speed of push" being the speed of sound? Love these types of videos...


Ya, I have known forever that sound traveled in water faster than air...but I didn't think of the larger implications of what this meant in reality. And just like light, there is a formula for calculating the speed of sound in objects, which by conscience is also the speed of change in the object, something I never placed in the same realm before (sound was related to motion in my mind, but in reality sound IS MOTION).

Woah...mind blown (twice). I mean, I knew that light was slower in air, but ~1M m/s slower? Crazy...

And the "speed of push" being the speed of sound? Love these types of videos...

Ah yeah... Mosquito saliva includes an anaesthetic, that's why you don't feel it.

I'm pretty sure the sudden inflation of 5-10 ml's of cold fluid at near the speed of sound into my highly nerve sensitive skin is going to hurt like hell.

Flesh expands around injections because skin and muscle is elastic. However the faster you expand it the more it's going to hurt and damage surrounding tissue.

You're basically being shot, point blank, by a miniature Railgun.

When I was in 5th grate, the teacher was telling us that the speed of light was the same as the speed of sound. Even the 10-year-old me knew this was false so I raised my had to say so, pointing out the obvious delay one sees when watching another person dribble a basketball some distance away. He still didn't believe me, but he was up for a wager and allowed me to run off to the library for an encyclopedia. I returned with the facts and won the bet, all of which he took very gracefully, unlike the teacher in the video here. In fact, what I won was less detention because the bet was for plus or minus one "demerit", which was his way of tracking small classroom infractions (e.g. missing homework, coming late, acting up) that could add up to a punishment assignment if you got three of them in a week.

Light doesn't have one set speed. Each frequency of light travels at slightly different speeds. I've long had this theory, and NASA has since confirmed it. We have detected very slight differences in the time it takes different frequencies of light to travel a set distance.

As such, we cannot say light has "a" speed, but rather a range of speeds. Therefore, could it also then be possible that the speed of an individual photon can be adjusted by various means in order to either speed up or slow down?

The answer is yes. Scientists have managed to slow the "speed of light" all the way down to 38mph. How is this possible? Well, as light has mass (albeit, a very miniscule amount), it will slow when traveling through a material, such as water, glass, oil, or even air. Passing the light through a super-dense, ultra-cooled material magnifies this effect.

As we already know different frequencies of light travel at slightly different speeds, and as we also already know, we can only visibly perceive a very narrow range of frequencies (for example, we cannot see infra-red or ultra-violet, or x- or gamma-rays), isn't it then perceivable that there are frequencies of light outside of what we can see that do travel faster than "the speed of light"?

And if this is true, then what else could travel faster? Are there things we can't even hope to detect simply because they exist in our timeframe for an impossibly short amount of time?

Part of the reason light is able to travel as fast as it does is its incredibly small (by our standards anyway) mass. What if mass is infinite? What if you could shrink yourself down to the size of a photon, or better yet, small enough to live on that photon as if it were the Earth. From your new perspective, the photon would appear to be very large, and as you are now traveling with it, that photon does not seem to be going as fast. You may see things that are even smaller and appear to move even more quickly, but something like the Earth would be imperceptible to you because you are so miniscule. It would be as the Universe to you--impossibly large, and inconceivably tangible. While you would know it is there, it would stand before you as a gigantic, unknowable concept, and things even larger than that would exist merely as mists of an imaginary daydream.

Now, imagine that the electromagnetic spectrum is infinite in both directions as well. Consider the possibility that, along with light, x-rays, gamma radiation, radio waves, and all the other things we know to make up the electromagnetic spectrum, sound is also part of that spectrum. Consider that light, being high in frequency exists near the top of what we can perceive of the spectrum, and sound is near the bottom. The vibrations become so slow and so wide toward the bottom that they effect the air and other matter around us, creating sound. And while we cannot see it, we perceive it with other sensory organs. Imagine that you could slow down light to the point that you can hear it, or speed up sound to the point that you can see it.

Now take another hit before that feeling goes away.

>> ^Jinx:

Raise your hand if you sat there counting the seconds after the flash until the bang to work out how far away it was.
\o


No, i just watched the youtube counter and used the speed of sound in air. Counted to 11, so that's about about 3.7km, what did you get?

>> ^hpqp:

Am I the only one whose first reaction when seeing the cannonball hole was "FAKE!!" ?

Tbh I had no idea a cannonball could do that kind of damage. I thought thay travelled a lot slower than 1000ft/s. Something with that kind of mass travelling at close to the speed of sound. I think I'd make sure there was a mountain or something between me and the nearest settlement when firing that thing.

And its not that surprising it missed those trash cans. A spherical projectile with no rifling? Yah, that shits gonna go anywhere it fucking pleases.

In a semi-related note my mum was missed by less than a metre by a bullet from a nearby shooting range when she was a teenager. I almost didn't exist due to similar accident as this

Where was the boom?

Oh wait, its another one of those videos with a low flying jet and a vapor cone. LOOK. COOL SHOCKWAVE TYPE THING AND A LOUD NOISE. I'D WAGER THATS THE SPEED OF SOUND THAT.

I want to add something to this comment. The estimates that celestial body will pass through the keyhole are 1 and 250,000. Not likely but still enough to warrant a good looking at. Perhaps when DeGrasse made this video it was still consensus that it was a 1 in 37 chance of passing into the Keyhole. That doesn't seem to be the case now. But that's not to say it can't happen, it's highly unlikely.

Astronomers have identified an asteroid named Apophis that was once estimated to have a 2.7% (1 in 37) chance of striking the earth in 2029. Further observations and revisions of the estimated path of the asteroid have resulted in an estimated 1 in 250,000 chance (0.0004%) of impact in 2036.[1][2] Apophis is estimated to be as large as 1,300 feet (400 m) across, and could cause millions of casualties if it were to hit Earth.[3] Astronomers think that Apophis will most likely miss a 2,000-foot (610 m) wide keyhole in 2029 which, if passed through, would cause it to hit Earth in 2036.[3]

http://en.wikipedia.org/wiki/Gravitational_keyhole#The_Apophis_Deflection

Ok, ok, ok. 2029 it may thread the keyhole, in which the next time it comes around 2036 would be BOOM! Excellent I can't wait. Shit that means I'll be about 50 years old! Fuck! A lot can happen between now and then.

On Friday, April 13, 2029, Apophis will pass Earth within the orbits of geosynchronous communication satellites.[10] It will return for another close Earth approach in 2036.

Precovery observations from March 15, 2004 were identified on December 27, and an improved orbit was computed.[11] Radar astrometry further refined the orbit. The 2029 pass will actually be much closer than the first predictions, but the uncertainty is such that an impact is ruled out. Similarly, the pass on April 13, 2036 carries little risk of an impact.

http://en.wikipedia.org/wiki/99942_Apophis

It's traveling at 30.728 km/s. Cars generally travel at Km/h. That's about 20 miles per second, and about 32187 Meters per second. If the speed of sound is 343.174 meters per second, then 32187/343.174 would mean that Apophis is traveling at 93 times the speed of sound. Which is just a comparison because things in space tend to have different physics than things inside an atmosphere.

http://www.wolframalpha.com/input/?i=speed+of+sound
http://www.wolframalpha.com/input/?i=20+miles+per+second
http://www.wolframalpha.com/input/?i=32187%2F343.174

This is a great comment. You should add it to the original vid so it gets seen.

In reply to this comment by NordlichReiter:
I'm pretty sure I made a comment on this already. So it's now 2029? Last I checked it was 2036. Ah, Wikipedia has conflicting data.

Ok, ok, ok. 2029 it may thread the keyhole, in which the next time it comes around 2036 would be BOOM! Excellent I can't wait. Shit that means I'll be about 50 years old! Fuck! A lot can happen between now and then.

On Friday, April 13, 2029, Apophis will pass Earth within the orbits of geosynchronous communication satellites.[10] It will return for another close Earth approach in 2036.

Precovery observations from March 15, 2004 were identified on December 27, and an improved orbit was computed.[11] Radar astrometry further refined the orbit. The 2029 pass will actually be much closer than the first predictions, but the uncertainty is such that an impact is ruled out. Similarly, the pass on April 13, 2036 carries little risk of an impact.

http://en.wikipedia.org/wiki/99942_Apophis

It's traveling at 30.728 km/s. Cars generally travel at Km/h. That's about 20 miles per second, and about 32187 Meters per second. If the speed of sound is 343.174 meters per second, then 32187/343.174 would mean that Apophis is traveling at 93 times the speed of sound. Which is just a comparison because things in space tend to have different physics than things inside an atmosphere.

http://www.wolframalpha.com/input/?i=speed+of+sound
http://www.wolframalpha.com/input/?i=20+miles+per+second
http://www.wolframalpha.com/input/?i=32187%2F343.174

I'm pretty sure I made a comment on this already. So it's now 2029? Last I checked it was 2036. Ah, Wikipedia has conflicting data.

Ok, ok, ok. 2029 it may thread the keyhole, in which the next time it comes around 2036 would be BOOM! Excellent I can't wait. Shit that means I'll be about 50 years old! Fuck! A lot can happen between now and then.

On Friday, April 13, 2029, Apophis will pass Earth within the orbits of geosynchronous communication satellites.[10] It will return for another close Earth approach in 2036.

Precovery observations from March 15, 2004 were identified on December 27, and an improved orbit was computed.[11] Radar astrometry further refined the orbit. The 2029 pass will actually be much closer than the first predictions, but the uncertainty is such that an impact is ruled out. Similarly, the pass on April 13, 2036 carries little risk of an impact.

http://en.wikipedia.org/wiki/99942_Apophis

It's traveling at 30.728 km/s. Cars generally travel at Km/h. That's about 20 miles per second, and about 32187 Meters per second. If the speed of sound is 343.174 meters per second, then 32187/343.174 would mean that Apophis is traveling at 93 times the speed of sound. Which is just a comparison because things in space tend to have different physics than things inside an atmosphere.

http://www.wolframalpha.com/input/?i=speed+of+sound
http://www.wolframalpha.com/input/?i=20+miles+per+second
http://www.wolframalpha.com/input/?i=32187%2F343.174