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Earth's Rotation Speed Question

  1. Jun 14, 2012 #1
    Hey everyone.

    My name is Ryan, I am a filmmaker and am not trained in science past high school.

    I am making a documentary about scientific facts in the Qur'an and have gotten up to the segment based on Physics, Astronomy, and Astrophysics. The information has been provided for me so I am just converting it into a linear documentary and learning along the way. While I was looking up information regarding the earth, I found out that it rotates on its axis at 1000 mph and this got me to think of some things that I cannot comprehend:

    I travelled to India last year leaving from New York, flying transatlantic East. My destination was approximately 7000 miles away and it took me 24 hours to get there with a 3 hour lay over.

    I also travelled to Thailand leaving from New York, flying to opposite direction across the pacific West. It took me roughly the same amount of time.

    So here's my question:

    If the earth rotates at 1000mph why did it take me the same amount of time heading in either direction. Why when traveling with the rotation is there not a significant decrease in time? For example it should have taken me 8 hours to get to Thailand or 7 to India, not 24. If the earth travels at 1000 mph why do we not fly against the rotation?

    I was told that the entire planet is rotating, including the sky. If this is true, same question why do we not fly against the rotation? If the earth is rotating at 1000mph and my plane travels 500 mph, how can it even get to its destination? The earth would catch up and pass the plane.

    I hope someone can explain this to me as if I were a child, and please do not copy and paste your definition from wikipedia or a textbook. Just because someone else says so doesn't make it true; Orson Welles read "War of the Worlds" over the radio in 1938 and the entire country panicked. Just because a billion people are regurgitating something one person says doesn't make it true. It may be a simple explanation, but like I said, I have absolutely no scientific training.

    Peace and blessings to all and thank you in advance,

    Ryan
     
  2. jcsd
  3. Jun 14, 2012 #2

    D H

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    Rhetorical question: When you jump up, why doesn't the Earth suddenly start flying by underneath you at 1000 mph?

    Obviously this doesn't happen. The answer lies in momentum. Suppose you jump a foot off the ground at the equator. When viewed by an inertial observer, someone who is not rotating with the Earth, you have a pre-jump velocity is 1000 mph eastward. Your jump up doesn't change this one iota. The inertial observer sees you as following a parabola. In that one second jump, you move up a foot, then back down a foot. You also move eastward about 5/18 miles. That spot you jumped from? It also moves eastward by about 5/18 miles.

    The same concept applies to an airplane. When it takes off it maintains its momentum it had right before takeoff. The Earth doesn't suddenly start rotating beneath the plane at 1000 mph, plus or minus the plane's takeoff velocity. Once in the air, the forces on the plane are gravity (downward), lift (upward), drag (against the wind), and thrust (forward). After it's initial climb, a plane moves at constant speed with respect to the air. Gravity and lift are in balance, keeping the plane at a constant altitude, and drag and thrust are also in balance, keeping the plane at a constant speed with respect to the air.

    Our atmosphere moves more or less with the rotating Earth. The plane does, too, plus or minus it's speed with respect to the air.

    In fact, a plane oftentimes gets better performance flying west to east, in the direction of the planet's rotation. The reason is that the airplane moves with the air. For the most part, the atmosphere does move with the planet. There are some exceptions to this rule. One of the most notable exceptions are the jet streams that move at fairly high speeds from west to east. Airplanes flying to the east will take advantage of jet streams if they can. Airplanes flying to the west, against the Earth's rotation, try to avoid those jet streams if at all possible.
     
  4. Jun 14, 2012 #3
    Thank you for the explanation, but I still don't understand:

    If we think of the motion as a body of water moving in currents it still provides a problem. When you travel with a current you go fast, if you travel against the current you go slower. If you walk up an up escalator you go faster, if you walk down an up escalator you go slower.

    If the sky is the same "body" as the entire planet, and the entire planet is moving at 1000mph, and we can travel through the sky as we can travel through the water, then why does it take the same amount of time going in either direction transatlantic or trans pacific?

    If you are in a boat on a river with a strong current and you hit the throttle you are going to go even faster than the current. If you turn your boat around, unless your engine is powerful enough, then current will at the very least slow you down and may even over power the engine.

    So what is the difference in the air?
     
  5. Jun 14, 2012 #4

    Janus

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    The difference is that with the water current, when you say you are going faster traveling with it than you are traveling against it, you are judging your speed relative to the shore to which the water itself is moving.

    When you are traveling in the air, there is no great difference between the Air and the Ground like there is for the water and the Shore. The land and air move together.

    In the River analogy is is like swimming from one raft to another where the rafts are floating free with the current. It will not take you longer to swim from raft to raft no matter which way you swim.

    If you looked at it from the shore you would see it like this:
    Boat leaves one raft and heads down stream. Relative to the Shore he travels at the speed of the current plus the speed of the boat. However, the downstream raft is traveling away from him at the speed of the current. By the time the boat has reached the point opposite the shore where the raft started, the raft has drifted further downstream.

    The boat has to chase down the raft. By the time it catches it. it will have traveled a long distance relative to the shore than the distance between the rafts.

    He turns around and heads back to the upstream raft. Now he is fighting the Current, however, the up stream raft is being carried by the current towards him. They meet after the boat has traveled a smaller distance relative to the shore than the distance between the rafts.

    Thus, according to the shore, the boat travels a long distance at a high speed going with the current and a short distance at a low speed going against it and the time done doing this is the same for both trips.

    So when you say the the Earth rotates at 1000 mph, this is relative to so reference point that does not share the Earth's rotation. This is like the Observer sitting on the shore. The plane is the boat and the air is like the water.
    The departure point and arrival points are like the rafts in that they do not move relative to the air, but do relative to the non-rotating observer, just like the rafts don't move relative to the Current but do relative to the shore.
     
  6. Jun 14, 2012 #5

    Nugatory

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    The air is moving at the same speed and in the same direction as the surface of the earth, so whatever your speed through the air, that's your speed over the ground (assuming no wind - headwinds and tailwinds do affect your travel time, just as you'd expect). But the river is moving relative to its banks, so your speed through the water is not going to be the same as your speed along the banks (which is what you care about if you're planning to dock at your destination sometime).

    The airplane flight without headwinds or tailwinds is like being in a boat on a lake with no current; the boat in the river with a current is like an airplane flight with a headwind or tailwind.
    (Also, notice that just like the current in the river, whether it's a headwind or a tailwind depends on which direction you're trying to go).
     
  7. Jun 15, 2012 #6
    As viewed from the shore, yes, as viewed from someone else drifting with the current, no.
    If there are two boats drifting with along the current 100 meters from each other, and you want to swim from the first to the second or the other way around, it is all the same to you.

    Same thing... Does it take you less time to walk a steps down vs a steps up, and does it matter which way the escalator is moving?
     
  8. Jun 19, 2012 #7
    Piggyback question:

    Is there any distance above the Earth that the atmosphere doesn't rotate as quickly as the Earth? I'm going to assume no, simply because there is essentially nothing in space to slow it down, but my question still stands.
     
  9. Jun 19, 2012 #8

    D H

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    Yep. At low altitudes, the trade winds from the equator to 30 north latitude blow from the northeast. So does the return flow at about 10-15 km altitude from the prevailing westerlies between 30 north to 60 north. A similar situation exists in the southern hemisphere. A diagram:

    winds_world.jpg

    These circulatory cells mean that there are regions in the troposphere where the winds blow faster than the Earth's rotation.

    The flow in the upper atmosphere tend to always be super-rotational, but only by 10 to 20 percent. Venus atmosphere is even weirder. There the upper atmosphere rotates many times faster than does the solid body, and in the opposite direction!
     
  10. Aug 30, 2012 #9
    Dear Ryan
    I hope you will understand by a simple example, suppose you are travelling in a bus, speed of bus is 50 mph. Now while in the bus, you move forward or backward.... what happens...

    Hope you understand
     
  11. Mar 26, 2014 #10
    The energy transfer between fluids is different than between solids. So to understand the hydraulics in college, you need three years of calculus and physics, two years of differential equations and fluid mechanics and finally two years to learn how all this applies.

    The main difference is that in the movement of fluids, the friction is negligible. On the flight of an airplane, which we could interpret as friction, is actually used to keep the plane flying. In other words, is not lost.

    That said, you yourself can calculate the difference in the kinetic energy of a geostationary mass at different heights, and the corresponding difference in potential energy.

    By comparing the algebraic result, notice the difference in potential energy is twice the difference of kinetic energy, which means that the difference in tangential kinetic energy is due only to the half of the difference of the potential, and the other half is lost, and is due to the force that must be applied to stop the fall.
    Furthermore, in the event one can sense that there is an exchange of tangential and radial kinetic energy.

    On the surface of the earth, as the radial force is always towards the solid floor, all possible energy transfers that contribute to vertical motion, ending in loss. Not in the case of aircraft (and subs?), where in addition is used to perform the maneuver of changing in altitude.

    By eliminating friction of the analysis, as has always said Bernoulli in the case of fluids, the flight of an aircraft must always be consider absolute, respect to the static center of gravity.
     
  12. Mar 27, 2014 #11
    Way to necro an ancient thread, and with nothing relevant in the post at that. You sir win the internet.
     
  13. Aug 19, 2015 #12
    At what altitude would one see the effect described in the original question (going too fast one way, and falling behind in the other direction), assuming that yes, the "atmosphere" also spins around at 1000 miles an hour? Where does the atmosphere end? Is there a part in the upper atmosphere where the effect would be half? Etc.
    Also, I understand the jumping up in the air thing, and the bus thing. But is the bus thing the same as the airplane thing, where you get up to pee and don't fall over by the speed? I also understand the riverbank reference versus the water, but that assumes that the atmosphere travels with the ground. What proof is there of the atmosphere traveling with the ground (besides the fact that we don't blow off the face of the earth obviously)? Those flat earthers will want to know.
     
  14. Aug 19, 2015 #13

    SteamKing

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    This thread is more than 3 years old. Let it Rest in Peace.
     
  15. Aug 19, 2015 #14

    russ_watters

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    The entire point here is that the effect described in the OP just plain doesn't exist -- altitude has nothing to do with it.
    There are arbitrary limits, such as 100 km, but those are just arbitrary definitions. In reality, the atmosphere gradually thins to nothing. Satellites at 200-300 km still experience a little bit of atmospheric drag.
    Since it is obvious, that's pretty good "proof".
     
  16. Nov 18, 2015 #15
    Alright then, the earth is traveling at 1040 mph. we human or other objects are attached to the earth by the gravitational force. so it means that we are also traveling at 1040 mph speed toward west.

    1) So, if we go toward east at a speed of 1040 mph what will happen?

    2) If we go faster than the speed of earth in the reverse direction will we be able to escape time?

    3) What will happen if we travel at double the speed of earth which is 2080 mph toward east?

    4) Is their any hope of going to the future? suppose if i travel in the west direction at triple speed of earth (3120 mph) will i be 1 day ahead of the other people of the world?

    Hopefully someone will answer my questions.
     
  17. Nov 18, 2015 #16

    SteamKing

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    Someone, please put this thread out of its misery already!
     
  18. Nov 18, 2015 #17

    SteamKing

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    You can reach London from Washington, D.C. in a little over 3-1/2 hours, excluding the time it takes to clear Customs and the security lines at the airport.
    No, but you can get to L.A. in time for dinner.
    Everything will happen that much sooner.
    We're all going into the future by 1 day, every 24 hours.

    Once you cross the International Date Line, just west of Hawaii, you will be 1 day ahead of many people on earth.
    I've tried my best.
     
  19. Nov 19, 2015 #18
    All motion is relative to something else. See G. Galileo, ca. 16th century.
     
  20. Nov 19, 2015 #19
    It may be over 3 years old, but its a new to me. I can in search of basically the same question
     
  21. Nov 20, 2015 #20

    D H

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    Done!

    Thread closed. If any of you reading this thread still have questions, please start a new thread of discussion.
     
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