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• The earth spins once per day which means that if you live at the equator,

• the surface of the earth with you on it is moving around a thousand miles per hour to the east relative to the center of the Earth.

• Even at 45 degrees latitude, the Earth's surface is moving 700 miles per hour to the east.

• So it kind of seems like it should be faster for airplanes to fly west.

• I mean their destination is literally spinning towards them.

• At the same time, however, they're spinning away from their destination.

• When we say the earth is going a thousand miles per hour to the east

• that means that the ground, and airplanes on the ground, and even the air above the ground are also moving a thousand miles per hour to the east.

• For an airplane to get anywhere, it has to start moving relative to the ground and through the air, at something like a hundred or so miles per hour.

• So when it flies east, it's actually moving a thousand plus a hundred mile an hour to the east.

• And when it flies west, it's actually moving a thousand minus a hundred miles an hour to the east

• Yes! To go west, you go east just slower than the Earth is going east.

• Unless you're within 10 or so miles of the poles in which case a brisk westward walk will take you legitimately west.

• That said a plane do often take different amounts of time to fly the same route in different directions.

• Because of wind in the upper atmosphere like the jet stream that they either have at their tail or have to fly into.

• The prevailing direction of these winds is largely caused by the Coriolis effect,

• which is caused by the fact that different parts of the Earth are moving east at different speeds,

• which happens because the Earth is round and spinning.

• So airplane travel times are influenced by the rotation of the Earth, just not in a straightforward way.

• This video is supported by audible.com the leading provider of audio books across all types of literature including fiction, non-fiction, and periodicals.

• If you're at audible.com/minutephysics, you can try audible free for 30 days.

• I highly recommend the book K2 by Ed Viesturs and David Roberts,

• about climbing the second highest mountain on Earth and all the human drama the successes and failures that have unfolded on its slopes.

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The earth spins once per day which means that if you live at the equator,

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# Why Isn't It Faster To Fly West?

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Loïc posted on 2015/12/19
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