If you could hover, would buildings crash into you?

15 November 2016


"The Blue Marble" is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometres (18,000 mi). It shows Africa, Antarctica, and the Arabian Peninsula.



If I could hover in the air totally unattached to the Earth, and I am hovering - let's say 2m from a building on its eastern side - would the building crash into me as the Earth rotates?


Chris Smith put this to physicist Andrew Norton from the Open University...

Andrew - The short answer is no, but I think you want a longer answer. We've got to understand the Earth is rotating and if we take the equator of the Earth, that's about 40,000 kilometers all the way round, and the Earth rotates once in every 24 hours. So if you're on the equator, you're moving at about 1,670 kilometers per hour. And here, a little bit further north, we're moving a little slower than that but nonetheless, we're moving very fast as the Earth rotates.

So, if you do decide to hover with your jetpack, or whatever it may be, then you've already got that sort of sidewise motion, whether or not you're hovering or standing on the Earth. So you and the buildings will continue moving sideways east to west at that same speed so, no the building wouldn't crash into you. You and the building would keep moving, keep rotating round the Earth with the speed that you've got.

I guess what you're thinking of maybe is if you could somehow take away that rotational speed that you've got by giving yourself an equivalent speed in the opposite direction, then that could well do it. But you'd have to work very hard to give yourself that extra speed in the opposite direction to cancel out the rotation that you start with.

Chris - A flight time to America is different in duration to a flight time from America though for the reason the Earth is turning to an extent, isn't it?

Andrew - It's partly because the Earth's rotating, partly also it's affected by the high altitude winds that either give you til wind or a head wind on the plane. But yes, the rotation of the Earth does make a difference to that.


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