How Does The Force Of Gravity Change As You Dig Yourself Down Into The Earth?

Long distance air travel sucks. Anyone who's ever had to sit on an airplane for 17 hours, indelible screaming babies, terrible net, and the constant threat of deep vein thrombosis knows how bad it sucks. I know, I know, information technology's the miracle of flight, and I actually shouldn't complain. But there'south got to be a amend fashion.

Well, I'one thousand happy to inform you, there is a better fashion. A faster way, where you lot tin travel halfway around the world in less than an hour, with no pesky seats, or even an aeroplane at all. All you lot need to practice is leap… down. Into that enormous tunnel bored right through the Globe connecting your location with the exact reverse spot on the Earth – your antipode.

Oh, yous don't take a tunnel like that nearby? That's probably because information technology's a terrible thought, completely impractical when you consider the massive engineering challenges to make something like that happen.

Just if you could, information technology would be pretty sweet. Here's how it would work:

The circumference, or altitude around the Globe, is approximately 40,075 km, merely that depends on where y'all measure information technology; around the equator, or from pole to pole. So, to travel overland from one location to its antipode, you'd demand to travel xx,037 km.

A tunnel, dug from one side of the Earth to the other would be, on average, 12,742 km. So information technology'south a shorter trip, sure, but that's not the best part.

If you jumped into the tunnel, you lot'd autumn down towards the center of the Earth, accelerating constantly, thank you to gravity. By the time you reached the halfway point, later on falling for 21 minutes, you'd be traveling at 28,000 kilometers per hour.

Once y'all crossed the halfway point, the velocity would bear you back up the other side of the tunnel for some other 21 minutes. This time, however, gravity is slowing you down, then by the time you reach the other terminate, y'all come up to a perfect end, merely every bit yous arrive at your destination.

In other words, the trip didn't require whatever energy. You exchanged gravitational potential energy for kinetic free energy on the way downward, and then exchanged information technology back on the way upwardly again. No energy was created or destroyed. We obey all the laws of thermodynamics here on the Guide to Space.

The fob is that you demand to make sure the tunnel is a complete vacuum, so that yous don't feel whatsoever air resistance during your journeying. That would cause you to fall at terminal velocity, and you'd stop up stuck at the center of the Earth, completely weightless and helpless.

I'grand sure the engineer in y'all is screaming obscenities at the screen right now. We tin barely dig a tunnel simply a few kilometers into the reasonable outer crust of the Globe. Forget digging down through the hotter part of the crust, into the mantle, where rock squishes and oozes around like jello. And you lot can completely forget digging through the Earth'due south metal inner core, which probably spins faster than the Earth itself.

Now, this is practically impossible on every level. However, this idea isn't completely terrible. Here's the absurd function.

If you dig a tunnel between whatever two points on Earth, you tin can even so take advantage of the Earth's gravity. Instead of traveling between two antipodes, y'all could travel a much shorter distance, without piercing so far down.

This concept is called a Gravity Railroad train. For instance, you could build a shallow tunnel from London to Paris, that only goes down about 55 kilometers. Evacuate the tunnel, and the gravity railroad train is pulled downwardly for half the journey, and and so decelerates naturally for the second half. And amazingly, the journey still but takes 42 minutes. No matter which ii points you connect, the journeying will only take 42 minutes.

Practically speaking, though, fifty-fifty a tunnel like that, which would dip into the Earth's mantle a niggling bit, is style beyond the engineering reach of anything nosotros can imagine. But who knows what amazing technologies we'll figure out in the future? Maybe some day you lot'll be able to travel around the Earth, using upwardly no energy, going anywhere you like in 42 minute train rides.

What two spots on Earth should be continued by a gravity train? Would y'all ride in one? Let us know your thoughts in the comments beneath.

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Citation: What if we dug a tunnel through the Earth? (2015, November 30) retrieved 17 March 2022 from https://phys.org/news/2015-11-dug-tunnel-earth.html

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