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Author Topic: Which way faster, east or west ?  (Read 20003 times)

Offline mawea

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Which way faster, east or west ?
« on: 07/11/2003 16:23:27 »
hello einsteins,

i have a question which has been bugging me for years, hope you guys can help me figure this one out.
say points A , B , C are on common latitude. A is west of B and C is east of B. distance from A to B equals B to C.
if 2 planes take off ( travelling on same speed) from B , one heading west to A the other heads east to C, which one will arrive at their respective destination first? assume there is no wind.

remember earth rotates from west to east ? do you guys think it would be faster to travel westward to A ?



 

Offline Pappy

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Re: Which way faster, east or west ?
« Reply #1 on: 07/11/2003 18:20:21 »
Traveling at same "ground speed" there is no difference. However, since the Jet stream flows from West to East, planes travel faster heading east than when heading west, against the jet stream. In oder for the earth's rotation (I'm just speculating here so feel free to help me out) to affect this scenario, the plane would have to be outside the effects of gravity.........???
 

Offline mawea

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Re: Which way faster, east or west ?
« Reply #2 on: 08/11/2003 06:01:11 »
Thanks Pappy, I believe ground speed is affected by wind also. In this case let us assume there is no wind, and maybe i should rephrase myself, plane heading to A travels with velocity V and the other plane travels velocity -V in nil wind, just incase some of you may have some confusion..forgive my english as it isnt my 1st language. Could you (or anyone) please elaborate on the possible effects of gravity in this case? I think both planes are subject to the same gravitational effects , I may be wrong though.
 

Offline Ians Daddy

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Re: Which way faster, east or west ?
« Reply #3 on: 08/11/2003 06:06:05 »
If you threw a ball from a moving car, it would travel with the car for a bit before gravity pulled it down....momentum.
If you pulled the chair out from under someone as they were sitting down, they would miss the chair and bust their a$$....deviance.

Now, my belief is that traveling westward would be faster. There's not enough momentum from the rotation of the earth to make a difference either way. However, the earth would move enough that a certain point (chair) would be moved from under the plane (a$$). So, I would speculate that west would be faster. (Not counting time changes)
But, my mind is now debating with itself. Great. I know it doesn't take much, but now I'm confused. Thanks alot!

Welcome to the forum, Mawea.
 

Offline mawea

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Re: Which way faster, east or west ?
« Reply #4 on: 08/11/2003 16:09:13 »
I think the momentum or inertia explanation is probably correct.
 

Offline Donnah

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Re: Which way faster, east or west ?
« Reply #5 on: 08/11/2003 18:27:07 »
Provided you are not factoring time zones or jet stream in the question, I think that the plane would land at A slightly ahead of C due to the earth's westerly rotation.
 

Offline tweener

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Re: Which way faster, east or west ?
« Reply #6 on: 09/11/2003 03:07:26 »
I think the key to this question is what velocity are you measuring?  If you are measuring velocity relative to the surface of the earth and assuming no effect from wind, then there will be no difference going west or east, because the rotation of the earth cancels out of the equations.

On the other hand, if you are measuring velocity relative to the center of the earth (as all spacecraft orbital calculations must, but aircraft do not) then the rotation of the earth will make a significant difference.  The linear speed of the surface of the earth due to the rotation is approximately 1,000 miles per hour at the equator, diminishing to zero at the poles.  This speed would be added to the eastbound plane and subtracted from the westbound plane, thus making a big difference in the "velocity".   However, since the starting point is moving along with the end points of both planes, the speed change still cancels out and they will both arrive at the same time relative to their departure.

I think I just canceled everything out!


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Offline UScaV

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Re: Which way faster, east or west ?
« Reply #7 on: 11/11/2003 00:06:00 »
I thought it didn't have anything to do with the rotation of the earth, but just the jet stream and the speed of it.  Not really sure why though, just what I was taught in class...
 

Offline tweener

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Re: Which way faster, east or west ?
« Reply #8 on: 11/11/2003 22:11:19 »
Actually, it doesn't have anything to do with the rotation of the earth because the atmosphere is rotating with the earth and the starting point of the "race" is rotating with the earth.  I didn't explain very well.


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Offline jojo

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Re: Which way faster, east or west ?
« Reply #9 on: 15/11/2003 10:39:37 »
if the earth were to rotate extreemly fast.. and i was to jump.. could i land in a different country? (assuming i didnt get hit by houses or anything..) :D.. hehe stupid question.. but jst wondering.. :)
 

Offline qpan

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Re: Which way faster, east or west ?
« Reply #10 on: 16/11/2003 13:20:18 »
If you take the wind relative to the earth's surface as being zero, then the relative velocity of the plane in ANY direction is the same, as it starts off travelling at the same speed as the Earth's surface. This is because at the start of the journey, when the plane is stationary, it is travelling at the same speed as the Earth's surface, therefore allowing you to negate the effect of the rotation of the Earth (Vel Plane = Vel Earth => vel plane rel earth = 0). Therefore, you can now take the Earth as not rotating as the realtive velocity is equal to zero at the beginning.
However, in real life, the wind relative to the earth's surface is not zero as the atmosphere generally rotates at a slower speed than the earth's surface and so, therefore, it will have to travel against the atmosphere in one direction and with the atmosphere in the other direction, and obviously it goes slower when travelling against the atmosphere.

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Offline chris

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Re: Which way faster, east or west ?
« Reply #11 on: 18/11/2003 18:19:47 »
So is the proposed plan for future air travel involving hopping up into near-space, sitting there a little while as the earth turns beneath you, and then landing in the right place, at all feasible ?

Chris

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Offline roberth

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Re: Which way faster, east or west ?
« Reply #12 on: 18/11/2003 22:13:01 »
I would guess it is feasible. The only problem would be the force required to break from the gravitational pull of the earth. I believe you need to be going at about 25,000 kms/hour, which is faster than most commercial aeroplanes can go these days. Then, of course, it would get warm coming back in.
 

Offline GlacierBlue

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Re: Which way faster, east or west ?
« Reply #13 on: 26/11/2003 22:34:57 »
Your original question was concerning which of the two planes would reach their destination first. The idea of "First" is strange and may be a bit more complicated than you originally thought. Take for instance an expierement done by the USAF in the 1960's. They took 3 ceasium isotope clocks that measure time in the billionths (nano-second). They left one on the ground and loaded the other two into identical fighter jets. Plane A headed due East, while plane B headed due West. The planes (after several refuelings) circumnavigated the globe and landed at the airforce base from whence the came.

When the clocks where compared, (several times over the last few years) it was discovered to no ones great surprise that the plane that had traveled East (against the rotation of the Earth?) had experienced several thousandths of a second LESS TIME than the plane traveling West. The clock left on the ground at the AFB confirmed that it wasn't an anomaly or error.

While this isn't news to many people, Einstein predicted the outcome of this experiment when he wrote the General Theory of Relativity. Time, he said was effected by the speed at which any object traveled. So, while this might only serve to confuse the issue of who gets there first, plane A or B, at the very least it makes for some interesting conversation. :-)


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« Last Edit: 26/11/2003 22:36:45 by GlacierBlue »
 

Offline chris

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Re: Which way faster, east or west ?
« Reply #14 on: 27/11/2003 00:18:45 »
What about the plane going west ?

Welcome to the forum by the way !

chris

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Offline GlacierBlue

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Re: Which way faster, east or west ?
« Reply #15 on: 27/11/2003 23:50:06 »
Good question Chris. I don't remember what the effects were on that plane. Lets puzzle it out. If you live through less time the faster you go, then it makes sense that you would live through more time the slower you go. So if you could slow down in relation to the people around you, it would look like they were in >> fast forward.

What is the theoretical limit of this assumption?

We can assume then that speed is a factor of the energy inherent in an object. When scientists try to cool an object down to absoloute zero (zero kelvin) they are trying to get molecular activity to cease. Maybe one of the reasons that they havn't been able to achieve zero Kelvin rests on the fact that in relation to the universe everything within it has some amount of velocity.

It would be intersting to experience temperatures near zero Kelvin just to see if the slowing of molecular activity increased the amount of time that you lived through.

At zero Kelvin however a persons atomic structure would age in relation to its decreased speed. The person would not "freeze" but rather disolve as the component building blocks of their atomic structure aged to death in "no time" in relation to the outside world.

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Offline qpan

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Re: Which way faster, east or west ?
« Reply #16 on: 04/12/2003 12:25:53 »
One of the reasons that scientists cannot reach absolute zero is due to quantum fluctuations. Another other reason is that in order to cool something very close to absolute zero to absolute zero, you still need a temperature gradient, and so, your temperature can only approach absolute zero as an aymptote as you cannot create the temperature gradient by having the surroundings at lower temperature than absolute zero.
Also, velocity is relative, so particles travelling at the speed of light can still be at zero kelvin as long as they have no relative velocities to each other (as it is equally valid for the particles to suggest that they are stationary and everything else is travelling at the speed of light towards them).
Also, at zero kelvin, the person's body would degrade not due to ageing infinately fast due to travelling at zero speed, but due to the electrons falling into the nucleus destroying all chemical bonds. The person would not age faster as particles in frozen foods move slower than particles in fresh foods but frozen foods don't decompose quicker!


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Offline george

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Re: Which way faster, east or west ?
« Reply #17 on: 04/12/2003 13:54:08 »
Errr I understood the top bit really well - thanks.

But I'm lost on this : "Also, at zero kelvin, the person's body would degrade not due to ageing infinately fast due to travelling at zero speed, but due to the electrons falling into the nucleus destroying all chemical bonds. The person would not age faster as particles in frozen foods move slower than particles in fresh foods but frozen foods don't decompose quicker!"

Can you clarify it a bit !
 

Offline qpan

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Re: Which way faster, east or west ?
« Reply #18 on: 04/12/2003 22:22:20 »
Yep- ok i'll try to clarify. As you all know, the body is made up of many chemical compounds. The only reason chemical compounds exist is so that the elements can share/donate/receive electrons to become more stable. However, at 0K, not even the electrons have any microscopic k.e. and so, fall into the positive nucleus (consider a planet in orbit- if it suddenly lost its speed, it would fall into the sun). Therefore, chemical bonds would break up due to the absence of electrons in their shells.
Also, to clarify further- protons take 10^32 years to decompose(theoretically- although none have been observed)- so the only way a body would decompose instantaneously due to decomposition of electrons is if the surroundings are travelling at near the speed of light- it is simply not sufficient to say that decomposition would happen instantaneously if the the microscopic KE is to equal zero. Also- ageing is different to decomposition- ageing is caused by oxygen free radicals released through respiration and decomposition is caused by the breaking up of compounds or subatomic particles (e.g. a proton)

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Offline qpan

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Re: Which way faster, east or west ?
« Reply #19 on: 05/12/2003 14:28:53 »
oops- in post above should be:
...........decompose instantaneously due to decomposition of Protons is if the surroundings are...........

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Offline Quantumcat

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Re: Which way faster, east or west ?
« Reply #20 on: 05/12/2003 14:46:03 »
You can edit you posts by clicking on the little button that looks like a notepad and pencil

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Offline tweener

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Re: Which way faster, east or west ?
« Reply #21 on: 06/12/2003 04:52:23 »
I don't think that electrons would fall into the nucleus even at 0 K.  I think the "lack of motion" only applies to the atoms and molecules, not the particles that make them up.  If the electrons stoppped, wouldn't they violate the wave equation and the uncertainty priniple?


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Offline qpan

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Re: Which way faster, east or west ?
« Reply #22 on: 06/12/2003 12:55:02 »
Well- if the electrons did not fall into the nucleus, the substance would not be at 0 K would it? If the electrons still have ke, would this not mean that the atom still had ke? The movement of a negative charge would surely incite movement in a positive charge as it would lose/ gain p.e.? This effect would certainly cause the temperature of the substance to rise as fluctuations in the positions of the electrons would incite the movement of all positive nuclei in the substance (please correct me if i am wrong!)

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Offline qpan

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Re: Which way faster, east or west ?
« Reply #23 on: 06/12/2003 13:04:13 »
actually- also read this forum here:
http://www.physicsforums.com/showthread.php?s=&threadid=5618
- it does make sense as i suppose the electrons cannot fall into the nucleus as it is one of the reasons absolute zero is not attainable (violation of heisenberg's law of uncertainty). Also, as i said earlier, you would not be able to cool something to absolute zero due to requiring an energy gradient (so it also violates the law of thermodynamics).
----So our debate is purely theoretical but about something which is actually theoretically impossible!--------

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« Last Edit: 06/12/2003 13:05:02 by qpan »
 

Offline tweener

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Re: Which way faster, east or west ?
« Reply #24 on: 07/12/2003 05:18:58 »
I read the forum thread and I still don't see anyone saying that the electrons will fall into the nucleus, or that the atoms will decay in any way.  I think the one post mentioned different definitions of temperature, and that may be the crux of the matter - what does absolute zero really mean.  

I certainly don't know.


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Re: Which way faster, east or west ?
« Reply #24 on: 07/12/2003 05:18:58 »

 

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