Funny Pic Thread VII - No swearing. No sex. No complaining. (READ FIRST POST)
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You know when an ambulance or police car goes past you the sound changes? It goes nenawnenawnenawnenawnenawnenawnenawNENAWNEEEnaaaawneeeenaaawneeeeenaaaawneeeeeenaaaaawneeeeeee?:headexplodes:
That is certainly beyond my comprehension.
I like my horrible pun better.
It's basically because it's catching up with the sound coming from it as it comes towards you, and it's moving away from the sound coming from it as it goes away from you. That changes the pitch (wavelength).
The effect affects all EM coming from (or being reflected from) the object, but most EM is very fast. Sound moves at 330m/s, which isn't very fast, so the 60-70mph that the ambulance is doing is actually an appreciable chunk of the speed of sound - about 10% of it. It affects light too, but you can't perceive it at these speeds - 30m/s is nothing compared to 300,000,000m/s
However, if something is going fast enough, you can see it, and the effect is the same. The "pitch" of the light changes so that something coming towards you has a shorter wavelength (higher pitch) as it catches up with its own light, and its light appears more blue, but something going away from you has a longer wavelength (lower pitch) and its light appears more red. The light literally "shifts", so something coming towards you is "blue shifted" and something going away is "red shifted". Stuff in the universe is largely going away from each other, so it all appears more red, and we can actually measure how far away something is by how much it is redshifted.
That also has the effect of making objects look shorter as they come at you and longer as they go away. Basically there's less distance between the light from the back of it and the light from the front as it comes towards you (for the same reason - the back is catching up with the light), and more as it goes away.
So the car coming towards him is blue-shifted and looks shorter, and as it passes and goes away it's red-shifted and looks longer.
From this we can surmise that the car is travelling at close to 98% of light speed, and that dude can turn his head real quick.
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ROAD_DOGG33J
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Ah, a one-make race. The exact same sound over and over and over and over and over and over and over and over again!
Still, I could almost smell the racing exhaust!
I have a video somewhere of Porsches coming out of Turn 7 at Sebring, that metallic sound they have in the exhaust when they upshift. Again and again and again and again and again and again and again!
Still, I could almost smell the racing exhaust!
I have a video somewhere of Porsches coming out of Turn 7 at Sebring, that metallic sound they have in the exhaust when they upshift. Again and again and again and again and again and again and again!
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My wife send me links to articles about our kids being able to be vaccinated.
I send her pictures like this.
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And I have to admit that I'm jealous of you and the others that get it.
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Thanks for the explanation. I would not have guessed it. Not in a million times. Strangely enough, I don't feel ashamed, frustrated or whatever negative emotion. I'm actually glad that you guys explained it to me.
EDIT: I thought it was a garage. I couldn't find out why there suddenly was a garage instead of a house.
EDIT: I thought it was a garage. I couldn't find out why there suddenly was a garage instead of a house.
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ROAD_DOGG33J
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