If Only ...

[RichardB]

If only I could afford to make it to Sheffield more often imagine what a great bunch of photos we could have ... alternatively, you might live there of nearby and could help please ? It's 280 miles round trip for part-time worker me.

[THYLACINE]

If only I could afford to make it to Sheffield more often imagine what a great bunch of photos we could have ... alternatively, you might live there of nearby and could help please ? It's 280 miles round trip for part-time worker me.

Me too!

[DaveH]

Me too!

He said a 280 mile round trip THYLACINE, - not a 23,0000 mile round trip.

Which, based on your present location is more or less what you would be facing. :o

[THYLACINE]

He said a 280 mile round trip THYLACINE, - not a 23,0000 mile round trip.

Which, based on your present location is more or less what you would be facing.

Thanks for reminding me Dave.

Since you're good at figures (I'll take that extra zero as a slip) if I were to take the shortest route, assuming I could withstand the 25,000 tons / sq. inch and 6000deg. C at the centre of the earth, how far would it be? And if I could dig in a straight line through the centre of the earth, how far from Sheffield would I be when I saw daylight? :rolleyes:

[Bayleaf]

Thanks for reminding me Dave.

Since you're good at figures (I'll take that extra zero as a slip) if I were to take the shortest route, assuming I could withstand the 25,000 tons / sq. inch and 6000deg. C at the centre of the earth, how far would it be? And if I could dig in a straight line through the centre of the earth, how far from Sheffield would I be when I saw daylight?

I dunno, but according to that fount of knowledge QI, it would take you 40 minutes to fall in one end and out the other!

[RichardB]

Thanks for reminding me Dave.

Since you're good at figures (I'll take that extra zero as a slip) if I were to take the shortest route, assuming I could withstand the 25,000 tons / sq. inch and 6000deg. C at the centre of the earth, how far would it be? And if I could dig in a straight line through the centre of the earth, how far from Sheffield would I be when I saw daylight?

I do hope you take into account the Chandler Wobble and the Mohorovicic Discontinuity when making this calculation.

[Stuart0742]

Thanks for reminding me Dave.

Since you're good at figures (I'll take that extra zero as a slip) if I were to take the shortest route, assuming I could withstand the 25,000 tons / sq. inch and 6000deg. C at the centre of the earth, how far would it be? And if I could dig in a straight line through the centre of the earth, how far from Sheffield would I be when I saw daylight?

Have a look at this

http://www.antipodemap.com/

[madannie77]

I do hope you take into account the Chandler Wobble and the Mohorovicic Discontinuity when making this calculation.

Congratulations on your bravery in quoting the Moho's full name and spelling it correctly: your next task is to pronounce it correctly as well lol

[DaveH]

Thanks for reminding me Dave.

Since you're good at figures (I'll take that extra zero as a slip) if I were to take the shortest route, assuming I could withstand the 25,000 tons / sq. inch and 6000deg. C at the centre of the earth, how far would it be? And if I could dig in a straight line through the centre of the earth, how far from Sheffield would I be when I saw daylight?

Sorry THYLACINE it was a slip.

With an estimated surface distance to Tasmania of 11,500 miles the round trip, without the extra zero (at least the comma was in the right place) is 23,000 miles.

As for your other questions, one of them involves a chord rather than a diameter through the Earth and the other requires non - Euclidian 3-dimensional geometry using great circles on the Earth.

As these are aspects of advanced mathematics that I don't use every day I will have to revise them a bit first but leave it with me.

In both cases the Earth would have to be approximated to being a sphere of uniform radius

[RichardB]

In both cases the Earth would have to be approximated to being a sphere of uniform radius

But, but, but ... it's an oblate spheroid ! :rolleyes:

[DaveH]

I dunno, but according to that fount of knowledge QI, it would take you 40 minutes to fall in one end and out the other!

If the hole contained no air so that there was no air resistance or drag as you fell through it high speed than this is more or less true, - it would take slightly more than 40 minutes, nearer 45.

The reason for this is that your entire motion, if you just "fell in the hole" is controlled by gravity and the force it exerts to accelerate you.

From a standing start in Sheffield you would accelerate towards the centre of the Earth.

Reaching this at a speed of around 18,000 mph you would have enough kinetic energy to overshoot it, - but now gravity would be trying to pull you back towards the centre, effectively slowing you down, decellerating you.

Gravity would bring you to a stop at the end of the hole at the antipodal point, from which you would of course emerge feet first, head nearest the ground.

Unless you could move out of the hole at this exact stationary point in your inconveniently inverted position you would be immediately pulled back in, falling in the opposite direction on your way home.

With no resistance to your motion this oscillating simple harmonic motion would continue indefinately. If there was any resistance or drag on your motion each oscillation would be smaller and slower, damping the motion and bringing you to rest finally in the Earths centre.

Interestingly, the motion of a rocket in orbit is also controlled entirely by the Earth's gravity. If you wanted to fly exactly half an earth orbit around the world you would have to be going at 18,000 mph to achieve orbit and it would take you about 45 minutes. Exactly the same.

[DaveH]

I do hope you take into account the Chandler Wobble and the Mohorovicic Discontinuity when making this calculation.

Chandler Wobble

I don't see how a 28,000 year "wobble" of the Earths's axis on space (caused by gyroscopic precession) would affect a fall down a hole through the Earth.

However, the Earth's norman diurnal axial rotation would tend to throw you against the side of the hole instead of straight down unless the hole went from pole to pole.

Mohorovicic Discontinuity

The sound change in density between crust and mantle would alter the gravitational constant, g, but the crust is a very small part of the journey (less than 50km) and of course it has a corresponding component at the antipodes which would effectively "cancel out" any discrepancies.

[DaveH]

But, but, but ... it's an oblate spheroid !

I know it is Richard,

But mathematically circles are simpler than ellipses.

Unless of course YOU want to do the maths! lol

[RichardB]

I know it is Richard,

But mathematically circles are simpler than ellipses.

Unless of course YOU want to do the maths!

Never was any good at Maths, I just got three great two word phrases in and thats good enough for me ... unless whilst banging against the walls and hitting the Moho we have to factor in The Moh Scale of Hardness for the materials encountered.

Mohs - "These Girls Can Flirt And Other ***** Things Can Do"

[DaveH]

Have a look at this

http://www.antipodemap.com/

Don't need that one Stuart, I can do it in my head!

Sheffield is 53 degrees 22 arc minutes NORTH and 1 degree 30 arc minutes WEST (according to co-ordinates finder).

Simple arithmetic tells me that the exact antipodes would therefore be

53 degrees 22 arc minutes SOUTH and 178 degrees 30 arc minutes EAST

This would indicate a point somewhere in the southern ocean to the south east of New Zealand.

[DaveH]

Never was any good at Maths, I just got three great two word phrases in and thats good enough for me ... unless whilst banging against the walls and hitting the Moho we have to factor in The Moh Scale of Hardness for the materials encountered.

Mohs - "These Girls Can Flirt And Other Queer Things Can Do"

Take it thats a mnomic for the Moh scale,

Would the first T be Talc and the final D be Diamond?

[Stuart0742]

Don't need that one Stuart, I can do it in my head!

Sheffield is 53 degrees 22 arc minutes NORTH and 1 degree 30 arc minutes WEST (according to co-ordinates finder).

Simple arithmetic tells me that the exact antipodes would therefore be

53 degrees 22 arc minutes SOUTH and 178 degrees 30 arc minutes EAST

This would indicate a point somewhere in the southern ocean to the south east of New Zealand.

Yes but us non clever people like to see it displayed graphically

Can't beat a map for displaying locations

[RichardB]

Take it thats a mnomic for the Moh scale,

Would the first T be Talc and the final D be Diamond?

Correct, just need to fill the rest in now.

Talc

Gypsum

Calcium ?

Flint ? Flouspar ?

A ? Amber ?

O ? Orthoclase ?

Quartz

T ? Tungsten ? Titanium ? Turnip ?

C ?

Diamond

[DaveH]

Yes but us non clever people like to see it displayed graphically

Can't beat a map for displaying locations

OK Stuart I'll leave this one for you as it gets rid of most the maths and introduces a solution using maps.

On a scale map of the south pacific locate my point given in the co-ordinates, measure from it to Tasmania (Lets say Hobart for accuracy of placement) and calculate the scale distance.

That would answer one of THYLACINE's questions about how far he would need to swim to get home after emerging from the hole.

Due to gravity of course, that whole would be drinking up half of the Pacific Ocean :o

[RichardB]

Due to gravity of course, that hole would be drinking up half of the Pacific Ocean

So, Mauna Kea gets its righful place as the tallest ...

[madannie77]

Correct, just need to fill the rest in now.

Talc

Gypsum

Calcium ?

Flint ? Flouspar ?

A ? Amber ?

O ? Orthoclase ?

Quartz

T ? Tungsten ? Titanium ? Turnip ?

C ?

Diamond

Talc

Gypsum

Calcite

Fluorite

Apatite

Orthoclase

Quartz

Topaz

Carborundum

Diamond

seems to be the correct list (didn't recall all of them from my geological period 15 years ago - had to do a bit of web searching to fill in a few gaps)

[vox]

Due to gravity of course, that whole would be drinking up half of the Pacific Ocean

Actually

Given the approximate diameter of Earth, and a comfortable man sized hole of 1.5 mts diameter,

I recon 22,500,00 cubic mts (22 500 000 000 ltrs) of it would be swallowed. (Give or take a bit for spillage ).

(But that's only if I correctly remember my sums from school) :)

[Bayleaf]

Can we stop now please, my brain hurts...:blink:

[Guest carlie167]

Whoa, this is all beyond me. I can't even read it, let alone understand it! :(

[RichardB]

Whoa, this is all beyond me. I can't even read it, let alone understand it!

Planet Earth with a long straw sticking through it, some science nonsense ... at least its not politics.