How Long Would it Take to Fall through the Earth: Yes, of course this is impossible, but just suppose.

jerryc41 Loc: Catskill Mts of NY

Yes, of course this is impossible, but just suppose.

http://www.popsci.com/how-long-would-it-take-to-fall-through-world?dom=rss-default&src=syn

John N Loc: HP14 3QF Stokenchurch, UK

Find a start point other than a pole (like where you live maybe) and use this little fun app. to find out where you'd exit.

http://www.freemaptools.com/tunnel-to-other-side-of-the-earth.htm

Looks like I'm in for a rough ride in the Southern Ocean!

jerryc41 Loc: Catskill Mts of NY

John N wrote:

Find a start point other than a pole (like where you live maybe) and use this little fun app. to find out where you'd exit.

http://www.freemaptools.com/tunnel-to-other-side-of-the-earth.htm

Looks like I'm in for a rough ride in the Southern Ocean!

I'd pop out SW of Australia.

JohnFrim Loc: Somewhere in the Great White North.

I recall the figure of 42 minutes transit time from my university physics days. In fact, if memory serves me correctly, a trip via the gravity slingshot to ANYWHERE in the world through a frictionless evacuated tunnel would take the same time of about 42 minutes. I don't recall the shape of the curve connecting the two points on the surface of the earth (parabola? catenary? hyperbola?) but the reduced gravitational force when not falling straight down toward the core is compensated by the reduced distance one travels between the points. A series of such tunnels between key locations would make an interesting intercontinental shipping system!!!

ebbote Loc: Hockley, Texas

Jerry, you would fall halfway, bounce in the center for awhile and die there, you can't fall up.

jerryc41 Loc: Catskill Mts of NY

ebbote wrote:

Jerry, you would fall halfway, bounce in the center for awhile and die there, you can't fall up.

Thanks! You've ruined my plans!

JohnFrim Loc: Somewhere in the Great White North.

ebbote wrote:

Jerry, you would fall halfway, bounce in the center for awhile and die there, you can't fall up.

Actually, you CAN "fall up" in a world where things can be massless and frictionless, as in the world of physics simplified. In this instance, after you jump into the hole you will oscillate between the ends with a period of 84 minutes. And that time is very close to the time for a satellite in LEO (Low Earth Orbit) to complete one orbit. All things are connected.

And of course you know there is no such thing as gravity; the Earth simply sucks.

WB9DDF Loc: Knoxville, IL

jerryc41 wrote:

Yes, of course this is impossible, but just suppose.

http://www.popsci.com/how-long-would-it-take-to-fall-through-world?dom=rss-default&src=syn

I can remember this problem in a third year Physics class. As it turns out, it takes the exact same time as half of an orbit of the earth at the altitude of the starting point. The trip from North to South pole and back to North takes as much time as one orbit of the earth. Furthermore is you dug a tunnel between any two points on the earth's surface such as New York and Los Angeles or Chicago and Paris and laid a frictionless railroad track and of course evacuated all the air, the trip would be the same time a one half of an orbit of the earth.

All that integral calculus was so fun at the time.

JohnFrim Loc: Somewhere in the Great White North.

WB9DDF wrote:

I can remember this problem in a third year Physic... (show quote)

Yup, what I said some 6 hours ago!!!

rmalarz Loc: Tempe, Arizona

John, the shortest distance between two points on the earth is a portion of the great circle which passes through those two points and whose center is at the center of the earth.
--Bob

JohnFrim wrote:

I recall the figure of 42 minutes transit time fro... (show quote)

JohnFrim Loc: Somewhere in the Great White North.

rmalarz wrote:

John, the shortest distance between two points on the earth is a portion of the great circle which passes through those two points and whose center is at the center of the earth.
--Bob

Bob, you are correct for travel over the surface. In this case we are considering a tunnel through the earth. Pole-to-pole would be a straight line, but any other two points would be some sort of curve whose equation can be derived from calculus, but I have forgotten most of that. It certainly is not a great circle.

rmalarz Loc: Tempe, Arizona

John, wouldn't it just be a straight line that doesn't pass through the center, then? Sort of like a chord of a circle.
--Bob

JohnFrim wrote:

Bob, you are correct for travel over the surface. In this case we are considering a tunnel through the earth. Pole-to-pole would be a straight line, but any other two points would be some sort of curve whose equation can be derived from calculus, but I have forgotten most of that. It certainly is not a great circle.

JohnFrim Loc: Somewhere in the Great White North.

rmalarz wrote:

John, wouldn't it just be a straight line that doesn't pass through the center, then? Sort of like a chord of a circle.
--Bob

I don't think it is a straight line; I really think it is a curve of some sort. At the bottom of the curve one would be moving perpendicular to a vertical line from the surface to the centre of the earth (or tangent to a circle/sphere at some depth below the surface).

Edit: OK, found the answer in Wikipedia. The shortest-time path is a hypocycloid, but straight-line tunnels all have the same travel time. So you are correct... in a way; and so am I. Check it out https://en.wikipedia.org/wiki/Gravity_train .

WB9DDF Loc: Knoxville, IL

JohnFrim wrote:

Yup, what I said some 6 hours ago!!!

So I see now but for some reason I didn't see your reply when I wrote mine.

aammatj Loc: Zebulon, NC / Roscoe, Ill

Interesting. wonder how long it would take if there were air in the hole.