Earth Rotation

[raptorsoft2000]

If a jet is flying 700 miles an hour against the Earth's rotation, would it effectively be flying at approx. 1400 miles an hour? ( earth's rotation = 700mph???? )

Example 2: If I leave in an airplane flying from Detroit to London, how do I arrive at my destination when the plane is flying slower than the Earth's rotation? Wouldn't I be moving backwards since I am not flying as fast as the Earth is moving?

 

[BrownTown]

when you launch you are already moving at 700MPH, newtonian mechanics apply in an intertial frame of reference, if you reference your movemnt to the earth below then you are going 500 MPH, if you are referencing it to some contant point in space then you are moving millions of miles an hour. Since everything around you is also rotating at hte same speed there it is no differnet than if it were all actually not moving at all.

 

[Vegitto]

See it like this: You and me are running against each other in a (speeding) train. The fact that the train is traveling 300 MPh or whatever doesn't mean that we're running at 300 MPh. It's relative speed .

 

[Peter]

Right. What matters is the speed of things in the system you're in.

 

[Vegitto]

Wow! I was right? I was just putting random words together .

 

[bisqeet]

so the speed of light isnt increased by racing a car and turning on the headlights...

 

[giantpinkbunnyhead]

Originally posted by: bisqeet
so the speed of light isnt increased by racing a car and turning on the headlights...

Whoa.. that's a whole new can of worms right there! That starts delving into the theories about nothing being able to exceed the speed of light, including light itself. I don't know what would happen for sure, but I'd guess only that the light would simply leave the headlights at a speed equal to c - v(speed of car). Otherwise... frame of reference applies.

 

[sao123]

Originally posted by: bisqeet
so the speed of light isnt increased by racing a car and turning on the headlights...

q]Originally posted by: sao123

Originally posted by: sao123
I recommend you all read Brian Greens 2 books on this subject and more. He answers all of your questions in a laymans manner for all to understand.

The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (Paperback)
The Fabric of the Cosmos : Space, Time, and the Texture of Reality (Vintage) (Paperback)

if you understand vectors, let me give you an oversimplified example.
Imagine you are moving at a constant velocity in a northerly direction. If you now begin to move in a easterly direction in addition to the northerly direction, but stay at a constant velocity... then your northerly speed magnitude must decrease.


Everything moves through spacetime(4d) at the speed of light. And this same property occurs. At complete rest, your entire vector magnitude, would be traveling though time (T) at the speed of light. As you begin moving in any of the otehr 3 directions (x,y,z), your motion through T, must decrease by that same amount. As an object reaches the speed of light, then its magnitude through T approaches zero. (time would stop at speeds of light.)

If a stationary body shoots a laser beam, the light will be traveling at C. If a moving body traveling at C/2 is traveling in the same direction as the laser, the light will also appear to be traveling at C. If you are able to travel at 1000C or 1000000000C, it will still appear to be traveling at C from the same, stationary source.

The reason this is so, is because of a mathematical limitations... watch.
As per above, something traveling at C in (X,Y,Z) travels through T at 0. Since speed is distance traveled divided by time, any distance in X,Y,Z traveled, divided by time = 0 (since time stops at velocity C) is undefined. Now you must read the books I posted to actually understand that which I have regurgitated to you from memory.

[/quote]

 

[BrownTown]

too bad Brian Green's theories are unprovable and almost certainly wrong. The basics are there of course, but string theory aint going anywhere so far. Only reason hes getting anywhere is cause hes a pretty good speaker and writer unlike other scientists. I've seen him speak on string theory, but so far all they have is theories and equations that work together, but no proof that hte theories and equation actually describe our universe, or just describe some imaginary universe. Until they actually get some proof I wouldn't start placing too much stock in their beliefs.

 

[silverpig]

Originally posted by: BrownTown
too bad Brian Green's theories are unprovable and almost certainly wrong. The basics are there of course, but string theory aint going anywhere so far. Only reason hes getting anywhere is cause hes a pretty good speaker and writer unlike other scientists. I've seen him speak on string theory, but so far all they have is theories and equations that work together, but no proof that hte theories and equation actually describe our universe, or just describe some imaginary universe. Until they actually get some proof I wouldn't start placing too much stock in their beliefs.

Thank you. I know a lot of the general public is swayed by his great media presence and are convinced that string theory is the real deal yet there isn't any proof yet. Granted, it MIGHT be true, but there's no experimental evidence to back it up.

 

[Woodchuck2000]

Originally posted by: BrownTown
too bad Brian Green's theories are unprovable and almost certainly wrong. The basics are there of course, but string theory aint going anywhere so far. Only reason hes getting anywhere is cause hes a pretty good speaker and writer unlike other scientists. I've seen him speak on string theory, but so far all they have is theories and equations that work together, but no proof that hte theories and equation actually describe our universe, or just describe some imaginary universe. Until they actually get some proof I wouldn't start placing too much stock in their beliefs.

Just out of interest, what higher knowledge allows you to state "...almost certainly wrong"?

String theory is still the only plausible and mathematically consistent GUT that I know of...

 

[BrownTown]

the "almost certainly wrong" part comes from the fact that throughout history many people have postulated theories of how the fundamental nature of out universe works, and very few have actually got stuff right. Maybe he is on to something, or maybe it will just be another theory that sounded good at the time, but turns out to be fundamentally flawed.

 

[sao123]

Originally posted by: BrownTown
the "almost certainly wrong" part comes from the fact that throughout history many people have postulated theories of how the fundamental nature of out universe works, and very few have actually got stuff right. Maybe he is on to something, or maybe it will just be another theory that sounded good at the time, but turns out to be fundamentally flawed.

Even if string theory is wrong.... the parts im speaking about havent even covered string theroy yet... What I just explained to you is all background infromation...
This is the explaination of Einsteins theory of relativity which has been proven true (and has nothing to do with string theory)... defining time and the like.

 

[IGBT]

..how about "rotational wobble"? the earth doesn't spin on a perfect axis. how does this wobble effect climate?

 

[BrownTown]

Originally posted by: sao123

Originally posted by: BrownTown
the "almost certainly wrong" part comes from the fact that throughout history many people have postulated theories of how the fundamental nature of out universe works, and very few have actually got stuff right. Maybe he is on to something, or maybe it will just be another theory that sounded good at the time, but turns out to be fundamentally flawed.

Even if string theory is wrong.... the parts im speaking about havent even covered string theroy yet... What I just explained to you is all background infromation...
This is the explaination of Einsteins theory of relativity which has been proven true (and has nothing to do with string theory)... defining time and the like.

yes, and thats why I said the foundations are correct, because what you were talking about isn't string theory and has at least some proof behind it. There really was no need to bring string theory into the discussion since what you are reffering to was postulated 100 years ago. I wasn't trying to say that anything you said was wrong, just that the guy who wrote the books you are reffering to is.

 

[dwcal]

One thing to add: The atmosphere rotates with the earth (more or less). Airspeed is what matters to a plane.

 

[mjia]

Regardless of it validity, "The elagant universe" is a great book and worth a read. In addition to the topics in covers concerning string theory, it also provides a good background on special and general relativity (though if you already understand these theories then it is a little redundant and worth skipping a few chapters). I would high recommend this book to anyone curious on this subject.

 

[Alastria]

I've always been intrigued by M-Theory more than String Theory, since M seems to use Many Worlds to explain the Big Bang (two branes colliding), dark matter (gravitons leaking off other membranes onto ours), etc.

 

[Spinne]

BTW, KSC is in Fl because it's more effecient to launch eastwards han westwards (the Earth's rot vel adds to that of the rocket), and since you want your test rocket to fly over an ocean rather than populated land, they picked the east coast. Now, the rot velocity is propertional to the distance from the axis, hence you want to be as close as possible to the equator. You still wanna stay on US soil for security reasons so you pick Cape Canavarel, FL!

 

[inveterate]

yup YOUR not moving,, everything is moving around you. Thats the way it's got to be

 

[DrPizza]

Originally posted by: BrownTown
the "almost certainly wrong" part comes from the fact that throughout history many people have postulated theories of how the fundamental nature of out universe works, and very few have actually got stuff right. Maybe he is on to something, or maybe it will just be another theory that sounded good at the time, but turns out to be fundamentally flawed.

Then again, throughout history, science and philosophy sort of went hand in hand... experiments weren't performed, careful, precise observations weren't made. However, have there really been that many theories in science in the past 200 years that were proven incorrect (versus being fine-tuned and improved upon?)

For example, Rutherford figured out there was a nucleus with the protons in it, and the electrons went around it, sort of like the planets around the sun. However, there were a few problems with that theory. Bohr improved on it with the concept that the orbits of electrons were at distinct energy levels. This explained the atomic spectrum of hydrogen, but again, wasn't perfect. The cloud model and quantum mechanics improved upon Bohr's model. But, going back to Rutherfords: the essential concepts: nucleus in the center, surrounded by the electrons, still stands as correct.

 

[beansbaxter]

This has nothing to do with newtonian mechanics, it's all relativity, and the foundations for Einsteins theories. Relative to a person standing on earth, the plane's going 700 MPH. Relative to someone floating in space watching the earth spin, the plane's going 1400 MPH. Relative to a person on the plane it's not moving at all. So whether you're moving backward, forward and how fast all depends on which reference you're observing from.

 

[rgwalt]

Originally posted by: bisqeet
so the speed of light isnt increased by racing a car and turning on the headlights...

No, velocity is not truly additive. However, at low velocities (like the speed of the rotation of the earth, even 700mph is very, very slow compared to light) velocities are very nearly additive.

R

 

[gsellis]

Back to the original post. Speed is measure relative to the ground or air. The air 'spins' with the planet at a similar speed (but that is very simplistic). So, we just ignore the rest of the motion and base it on ground speed or air speed.

Classic example - HNL to LAX speed records for passenger liners. The airplanes do around 600mph. If they get a strong jet stream (tail wind), they can do 750mph relative to the ground. Still only flying 600mph for airspeed. Ground speed might be over Mach, but no boom as they are still below Mach in airspeed.

Oh, and if you really want to get tricky, the earth has a speed around the sun, and the sun is moving in the galaxy, and the galaxy is moving. I read it once, but forget the true speed, but your example might be that the jet is moving 10,000 miles/min - backwards.

 

[alpha88]

While I'm a physicist, and the majority of these answers are correct (and I've even met Brian Greene and pointed out that his socks didn't match)...

In general (as in everyday life), it's safe to approximate the earth as flat and not in motion. This is because the earth is slightly larger than we are.