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The golden bird can only fly at 5 mph. That is the only way the bird can move. The bird must stop flying and rest its wings for 5 hours immediately after every hour of flying it does. That is the only way the bird can rest so it can continue flying. The ocean is 6 miles wide. The golden bird flies over the ocean and makes it to the other side without resting. How is this possible?

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    $\begingroup$ Congratulations, your question has made it to the top of today's hot network questions: stackexchange.com/questions?tab=hot $\endgroup$ – Kenshin Nov 17 '14 at 10:49
  • $\begingroup$ Hey, cool, network question status! :D $\endgroup$ – DivideByZero Nov 17 '14 at 14:26
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    $\begingroup$ @Twinkles That would be true if the bird were flying in outer space. The atmosphere rotates with the earth, and so would the bird. That's why we don't have permanent 1040mph winds :) $\endgroup$ – Tymric Nov 17 '14 at 17:54
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    $\begingroup$ Is gliding allowed? Is that "resting"? This site says some birds can glide for 20 metres for each metre of lost altitude, so in the first hour it would only need to reach an altitude of 264 feet or so, ignoring thermals, etc. $\endgroup$ – Ken Y-N Nov 18 '14 at 5:35
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    $\begingroup$ The bird crossed a time zone, so while the difference in local starting time to local stopping time was one hour, the bird's actual range was ten miles. $\endgroup$ – Noctis Skytower Nov 18 '14 at 15:31

16 Answers 16

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The bird's speed is 5 mph. If

the speed of the wind across the ocean is greater than or equal to 1 mph towards the direction the bird is flying*, the overall speed of the bird will be greater than 6 mph,

and it can easily reach the other side of the ocean without resting.

So that means

the speed of the ocean wind at that time must have been at least 1 mph in the same direction the bird was flying.

And hence the bird reached the other side of the ocean without resting.

This picture illustrates the point:

*Or greater than or equal to √2 mph to any angle not more than 45˚ from the direction of bird's flight. If greater than 45˚, it needs to be more than √2 mph, depending on the angle.

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  • $\begingroup$ Too easy to be true, and not alwzys true ! $\endgroup$ – Gil Sand Nov 17 '14 at 7:57
  • $\begingroup$ Yes. It's not always true. But whenever there is a wind with the mentioned speed, it will be true and more practical too. $\endgroup$ – AeJey Nov 17 '14 at 8:51
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    $\begingroup$ +1 this is how passenger jets save time on long-haul flights. $\endgroup$ – oliver-clare Nov 17 '14 at 10:11
  • $\begingroup$ Nothing here really needs to be spoiler-hidden. Nonetheless, I've suggested an edit to keep the kernel of your answer disguised. Hiding the entire answer doesn't really help readability, because then I can only see all or nothing of the answer. $\endgroup$ – Josh Caswell Nov 17 '14 at 19:59
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    $\begingroup$ I did it with pixlr.com/editor/ (an online tool similar to photoshop). In my office pcm there is no Photoshop available, and so I use pixlr editor for my image editing needs at office. ;) $\endgroup$ – AeJey Nov 18 '14 at 4:41
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"The other side" meaning, "the heavenly realm" - i.e. the bird didn't make it across the ocean but died in mid-air.

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    $\begingroup$ Same punch line as "Why did the chicken cross the road?". $\endgroup$ – Aura Nov 17 '14 at 16:16
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    $\begingroup$ @Aura OMG I've heard that joke so many times and never got it until now... :O $\endgroup$ – oliver-clare Nov 17 '14 at 16:17
  • $\begingroup$ @LordScree It's actually kind of dark. $\endgroup$ – Aura Nov 17 '14 at 19:22
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    $\begingroup$ @LordScree I have to admit the same thing - I never realised there was another meaning to "The Other Side" in that old joke - just thought it was supposed to be "Why else would it cross the road, stupid?". But I think you're right! $\endgroup$ – Lefty Nov 17 '14 at 19:35
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    $\begingroup$ "Why did the chicken cross the Mobius strip?" "To get to the other ... oh, forget it!" $\endgroup$ – Rand al'Thor Nov 18 '14 at 15:41
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While this particular ocean is 6 miles wide, its length is considerably less.

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    $\begingroup$ Length: the measurement or extent of something from end to end; the greater of two or the greatest of three dimensions of an object. Wouldn't length have to be in this case more than the width? When you mention an ocean the width should be the smaller one and length the longest one, right? $\endgroup$ – Sinan Samet Nov 17 '14 at 9:43
  • $\begingroup$ Good point Sinan. Luckily a found this definition: "the linear extent or measurement of something from end to end, USUALLY being the longest dimension or, for something fixed, the longest horizontal dimension" so length may only USUALLY be the longest dimension ;) $\endgroup$ – Kenshin Nov 17 '14 at 10:42
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    $\begingroup$ Ah, okay. I find it a hard subject to go on with after researching a little more and it seems to be an opinion based thing. Still I would like to share this information just because I kind of find this interesting. mathforum.org/library/drmath/view/57801.html and another "math dictionary": mathworld.wolfram.com/Length.html $\endgroup$ – Sinan Samet Nov 17 '14 at 11:03
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    $\begingroup$ As much as I agree with @SinanSamet on this, I feel the definition of ocean is the real problem for @Mew: oxforddictionaries.com/definition/english/ocean and oxforddictionaries.com/definition/english/expanse are my sources. "A large continuous area", suggests it would be less likely to be significantly wider or longer in one dimension. $\endgroup$ – oliver-clare Nov 17 '14 at 15:02
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    $\begingroup$ @LordScree, good point, but it is strange enough that the ocean is only 6 miles long, so not too far a stretch to have a tiny ocean in the bizaar universe this question resides in. $\endgroup$ – Kenshin Nov 17 '14 at 15:16
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The golden bird flies without rest inside the cabin of an airplane or helicopter, which takes less than one hour to fly over the ocean.

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    $\begingroup$ This violates "That is the only way the bird can move". $\endgroup$ – Rand al'Thor Nov 17 '14 at 12:17
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    $\begingroup$ Lol, this is exactly the same I answered, but then without all the backstory :P and @randal'thor: It doesn't violate that, as the bird is still moving only by flying, it's just that it's reference frame for it's speed is different (due to less air resistance and stuff). $\endgroup$ – David Mulder Nov 17 '14 at 17:40
  • $\begingroup$ @DavidMulder and GOTO0: Oops, I missed the word 'flies' in this answer! Sorry. $\endgroup$ – Rand al'Thor Nov 17 '14 at 17:43
  • $\begingroup$ How exactly is it possible to have a bird flying 5 mph in a helicopter flying > 6 mph for any reasonable amount of time? I would love a better explanation as to how this works (and scientific proof, if necessary). $\endgroup$ – DivideByZero Nov 18 '14 at 4:28
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    $\begingroup$ @user3155415 Option 1: the bird is flying around in a loop; option 2: the plane is very long; option 3: the plane is very fast; option 4: for a scientific proof, have a look at physics.stackexchange.com, just don't use the word-problem tag ;) $\endgroup$ – GOTO 0 Nov 18 '14 at 6:45
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The Golden Bird is obviously the bird captured by the prince (see the wiki link on "The Golden Bird" at the beginning). What the Grimm brothers missed out on though was that after the Golden Bird the Golden Cat came first, before the Golden Horse. So, when the Golden Bird explains to the prince that to get the Golden Cat the Golden Bird has to fly to the other side of the 6 miles wide ocean without resting, the fox advises the prince to use the wooden boat in the castle and peddle it at a speed of at least 6mph whilst the bird peacefully will fly inside its cage1. Sadly the prince fails, as he ignores the foxes advice and instead uses the Golden Boat, which is far too heavy to peddle that fast, but that's not important now.

1 Of course the cage is covered by a piece of cloth, otherwise air resistance would make this impossible.


And just for the record and for fun: The answer I originally wanted to give was the following:

The Golden Bird is obviously from a fairy tale (before I realized that it really was from a fairy tale). And as commonly known fairy tales do not happen on this earth, so they must have happened on another earth. And as commonly known other earths are not necessarily round, nor does gravity necessarily behave in the same way, so in this particular case the bird simply flew over the mini ocean that was located in a deep hole.

enter image description here

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The bird speed is expressed in Irish miles, with 1 Irish mile = 2.048 km.

The ocean's width is expressed in normal miles, with 1 mile = 1.609 km.

The bird flies at 5mph for one hour and covers 5 * 2.048 = 10.240 km to cross the ocean that is 6 * 1.609 = 9.656 km in width.

Source: http://en.wikipedia.org/wiki/Mile

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  • $\begingroup$ Will also work for knots then: one knot is one nautical mile per hour. One nautical mile is 1.852 km. $\endgroup$ – cst1992 Apr 9 '16 at 13:16
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The bird is on a artificial small planet (gravity doesn't matter but lets say its artificially the same as on earth) it has only 2 land masses and a ocean, the two landmasses are a small island (where the bird is) and a bigger continent. The island is located on the ocean like so that its 6 miles away from the main land on one side and only 5 miles on the other side. So it just flies in the other direction.

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The bird flies up, it doesn't go parallel with the ocean. When it should rest, it just falls down in the direction of the land side, so it falls to his death at the other side. But at least it's there.

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    $\begingroup$ +1 OP didn't say the bird was alive at the other side. $\endgroup$ – oliver-clare Nov 17 '14 at 9:55
  • $\begingroup$ ... but... the OP did say the only way the bird can move is by flying. So we have to assume it stops mid-air instead of falling. $\endgroup$ – oliver-clare Nov 17 '14 at 10:09
  • $\begingroup$ Well, the discussion is, what exactly is 'rest its wings'. If it means sitting down, then this answer is wrong. But by falling down, it doesn't use its wings, meaning it's resting.. but that's open for discussion :-) $\endgroup$ – Gudgip Nov 17 '14 at 10:11
  • $\begingroup$ I know where you're coming from, but falling is still moving, and the OP explicitly said that the only way for the bird to move is by flying. Still a good, morbid answer :) $\endgroup$ – oliver-clare Nov 17 '14 at 16:14
  • $\begingroup$ I think you're right. I'll keep the answer just for fun :-) $\endgroup$ – Gudgip Nov 18 '14 at 7:59
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Could it be that the Earth is round, so the bird just gonna fly in parallel with the diameter of the earth to reduce the distance to 5 mph.

Edit: Analysis to completely trashed this idea of mine.

Suppose the radius of Earth $R=6371\mathrm{km}$. To obtain the arclength $C=6\mathrm{m}$, we need to travel $\theta=6/6371000=9.417\times10^{-7}\mathrm{rad}$. So if the bird fly parallel to the diameter of the Earth, it will be $L=2R\sin{(\theta/2)}=5.999\mathrm{m}$. If you use common sense and think about this physical world, this should be obvious too. Maybe I've not been going out to the real world for too long, and I lost my common sense about the world. Probably.

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  • $\begingroup$ It depends, can you support that answer with a little math? (note that by commenting I am not validating your answer, but am merely interested in another, less intuitive answer than the one I had). $\endgroup$ – DivideByZero Nov 17 '14 at 3:52
  • $\begingroup$ Edited to completely trashed my solution. $\endgroup$ – nexolute Nov 17 '14 at 4:36
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    $\begingroup$ +1 for math although answer is not viable. I think a side-effect of hanging out on puzzling.se is losing common sense about the world so you can come up with subtle answers... $\endgroup$ – DivideByZero Nov 17 '14 at 4:46
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Try this one on for size:

The Golden Bird only moves 5mph - but it can choose the reference point! Normally we would expect it to fly 5mph relative to the ground / the planet it's on. But that means (assuming earth) the Golden Bird is moving ~67,000mph relative to the sun. That's ~492,000 mph relative to our galaxy. So we need to know what it's moving at 5mph in relation to - and the answer is: it chooses. If it can choose to move at 5mph relative to an airplane which is itself moving at >= 1mph across the ocean (relative to the ocean, of course), than the Golden Bird will cover the 6 miles (relative to the ocean) in just a single hour.

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  • $\begingroup$ Fantastic answer, relative to the reference point of the average answer this question would get on Facebook of course. +1 :) $\endgroup$ – DivideByZero Nov 18 '14 at 22:51
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The bird is flying normally with 5 mph and it mades it to the other side of the ocean, because the water underneath is moving. For example, a high tide starting at the same time as the bird's flight and with development direction opposite to the bird's flight direction. If the high tide has a peak in an hour and the water displacement is about 1 mile, there you go, the bird succeded in its adventure.

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  • $\begingroup$ Flying is the only way the bird can move. Please remove answers 1+2 unless they can be made to fit the prompt. $\endgroup$ – DivideByZero Nov 18 '14 at 22:47
  • $\begingroup$ if you insist.. $\endgroup$ – zlobi.wan.kenobi Nov 19 '14 at 10:19
  • $\begingroup$ Sorry, just trying to keep answer quality up. +1'd for creative tidal answer. $\endgroup$ – DivideByZero Nov 19 '14 at 23:08
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A few ideas:

  1. Bird flies for 1 hour, then dies and falls in the ocean. The tide washes her up on the shore.
  2. The golden bird is owned by a prince, who sails the ocean in his luxury yacht. The bird doesn't even need to fly, but the prince lets her out for a fly near the end of his journey, so the bird flies over the ocean and makes it to the other side without resting.
  3. The golden bird flies for an hour (making five miles' progress in the air) and then glides down to land on the other side. Gliding is not the same as flying and it's reasonable to assume that an ocean bird can glide for 1 mile.

None of the above answers satisfy the "that is the only way the bird can move" criterion.

EDIT: JUST THOUGHT OF A FORTH!

  1. The bird flies at 5mph, but the earth is rotating towards the bird at >= 1mph, therefore the bird travels 5 miles in the time it takes the earth's surface to travel 1 mile or more = 6 miles or more and the bird lands safely.
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  • $\begingroup$ #3 was my suggestion, too. $\endgroup$ – No. 7892142 Nov 17 '14 at 13:41
  • $\begingroup$ That triple negative... "not unreasonable ... cannot" => "not reasonable ... can" - seems to be the opposite of what you mean. Try dropping the not - and make the other two positive for ease of reading. $\endgroup$ – Bob Nov 17 '14 at 15:35
  • $\begingroup$ @Bob cheers, I don't disagree with your comment and have adjusted accordingly. $\endgroup$ – oliver-clare Nov 17 '14 at 16:07
  • $\begingroup$ "None of the above answers satisfy the 'that is the only way the bird can move" criterion.' - if they don't fit the prompt, I would suggest that you delete them as they are not answers to this question. $\endgroup$ – DivideByZero Nov 18 '14 at 22:44
  • $\begingroup$ @user3155415 thanks for the comment - it does depend on how strict you were being with that part of the question - many of the other answers given here also did not satisfy that requirement and there are many answers on SE that do not provide a complete answer to the question, but are still of use, or offer an alternative viewpoint. Technically, the accepted answer also violates the movement constraint given that the bird is effectively being pushed. $\endgroup$ – oliver-clare Nov 19 '14 at 12:57
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Well everyone has already answered all the good serious answers. The only serious one that appears to be missing is

  • The bird can rest it's wings by gliding, which is exactly how birds that fly over large expanses of water rest. He builds altitude during his hour of flying, and glides, slowly burning altitude, while resting his wings.

alternatively

  • the bird lived on an island in the center of the ocean all his life. When he finally chooses to cross over the ocean to the other side he finds it takes nearly 50 minutes to fly from his island all the way to the far side of the ocean, sure is good he didn't live on the other coast or he would never have made it!

or, to take the last answer to an even more annoying extream

  • The golden bird one day decides to fly over the ocean. Flying part way there he decides to rest by landing on the water and floating awhile, being a golden duck and all. After awhile he gets bird and starts up his flight again. When he decides to fly again he flys over the ocean and to the other side without any rest that flight.

Of course if we really want to be annoying we can start playing with pronouns and proper names:

  • the bird's 5 MPH is defined as his total average speed for a long trip. Meaning that he is taking an hour of travel, 5 of rest, then repeating over and over. Because of this the speed he travels at while in motion is actually 30 MPH, making it quite easy to cross the ocean.

  • "the other side" is the name of a popular party boat, currently in the middle of crossing the ocean.

  • 5 MPH is the name of the only ocean at which the Golden Bird is capable of flying. He can, however, manage quite fast speeds over the "5 MPH" ocean.

  • The Golden Bird can only fly 5 MPH and crosses the ocean. His friend The Bird (who's feathers are not nearly as brilliant) must rest after every hour of flying. It is a good thing that The Golden Bird can fly much longer then The Bird can.

  • The ocean is the name of a huge moving lava flow. The bird flys for 5 hours to cross it, luckily the lava flows more then 1 MPH the other way at the same time.

  • 'IT' is the name of The Golden Bird's BFF the albatross. The Golden Bird must rest after It the albatross has flown for an hour, because 'It' gets tired easily and the Golden Bird would never leave his tired friend. Sadly one night while flying over the ocean It the albatross was shot down by a ship full of hunger lateral thinking puzzlers (who all have a strange uncontrollable fear of tasting soup). The Golden Bird is so shocked seeing his friend It killed after only 30 minutes of flying he keeps flying for hours crying!. Wanting to get away from the horrible memory he flys all the way to the other coast, which he was never able to reach while he had to rest with IT every hour. In his outrage The Golden Bird swears to force all future puzzlers to figure out the story behind how his doomed voyage, in hopes that they will learn to leave poor easily-tired albatross alone, and also stop being cannibals of course.

yeah, okay sorry I got carried away there. I've had an image of an albatross in my head that I needed to get out since reading this puzzle! My apologies to all those that don't get the allusion. Lets move away from messing with names and pronouns, that's just too easy.

  • The bird flys five miles across the ocean before landing on the ocean and floating while because his wings are growing tired and he is hungry. However, his landing isn't the restful Fishing reprieve he had hoped for. A storm blows in even as he starts diving for fish, and it rapidly grows. The poor bird finds himself paddling for dear life just to stay above the waves and turbulence. He tries fishing for hours, despite the difficulty in catching fish in such turbulent waters, in hopes of settling his gnawling hunger. He keeps hoping the storm will die out as quickly as it started so he can start flying again, but after 5 hours of none stop paddling just to try to keep his head above the water he comes to realize this storm isn't going to end any time soon. The poor bird is exhausted from his time at sea, and doesn't know how he can manage any strain on his weary body, but he realizes the only hope of surviving this storm is reaching dry land, no matter what that takes! The only good news is that muscles of his wings have recovered slightly from the strain of flight during the hours trying to wait out the storm, if only he had the energy in the rest of his body for the exertion of flight!. With an exhausted and desperate strain he somehow manages to climb into the air, though he doesn't know where he finds the energy. He drives on through the ferocious storm towards dry land and safety. He is so tired he doesn't know how he finds the energy to beat his rested wings, but the need to survive drives him. Finally he seen land, with one last deperate dive he swoops in to the safe dry grown, too exauhusted to even try to find a try to rest on; he can only hope no preditors come to find him sheltering against the storm before he recovers enough to start searching for a safer place to stay. He can barely believe he made it through the hours long ordeal without a rest, he will never try crossing that ocean while it's raining that's for sure! The poor tired bird tucks his head under his golden wing and settles in for his first rest in over 6 hours.
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I'll go along the lines of what others have said about the planet being peculiar. The atmosphere of said planet is very low and the bird can survive outside of the atmosphere. Additionally, the said planet spins rather fast. This means the bird flies out of the atmosphere, the planet spins, moving in the opposite direction the bird is flying in. So the bird travels at most five miles, while the planet spins the missing distance.

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  • $\begingroup$ there is so many things wrong with this m8 $\endgroup$ – Vajura Nov 17 '14 at 10:10
  • $\begingroup$ @Vajura Would you mind pointing out where I broke the rules of the question? My logical answer would have included wind (AeJays answer), but that was already taken. $\endgroup$ – SBoss Nov 17 '14 at 10:13
  • $\begingroup$ If the bird would leave said planet it would still move in the direction of the rotation $\endgroup$ – Vajura Nov 17 '14 at 10:19
  • $\begingroup$ @Vajura Good point. Maybe a weaker gravity would solve that problem. $\endgroup$ – SBoss Nov 17 '14 at 10:21
  • $\begingroup$ Gravity doesnt matter in this equation rather hard to explain over here. Go check out why space rockets go at a hard angle when they leave the orbit. The same principle would apply here. Lets say the sun is directly above the bird at all times and you can see the birds shadow at any distance. The shadow of the bird will always stay on the same spot even after it leaves the athmosphere because it will keep moving in the direction of the rotation. $\endgroup$ – Vajura Nov 17 '14 at 10:24
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On its journey it gets hungry and looks for food on the back of a stationary whale for more than one hour.

  1. The bird was looking for food, therefore not resting.
  2. The OP didn't mention that the bird should not stop flying.
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  • $\begingroup$ "that is the only way the bird can move" - by flying. This violates that criteria. $\endgroup$ – DivideByZero Nov 17 '14 at 14:23
  • $\begingroup$ @user3155415: the whale is stationary. This doesn't violate anything. It takes its 5 hours rest sitting on the whale. I was about to post this. $\endgroup$ – smci Nov 17 '14 at 21:25
  • $\begingroup$ The whale does not seem stationary, as is evidenced by "heading the same direction". A good edit could fix that, though... $\endgroup$ – DivideByZero Nov 17 '14 at 23:02
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The ocean is six miles wide only at its widest, or on average. It can be five miles wide or less at some other point, allowing the bird to cross the ocean at this narrower point.

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