Discussion:
a question
(too old to reply)
Kamath Raj
2003-10-12 11:29:59 UTC
Permalink
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Sam Wormley
2003-10-12 12:06:05 UTC
Permalink
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Survey quality GPS
http://www.trimble.com/news/052198a.htm
http://www.trimble.com/gps/mteverest.html
Richard Herring
2003-10-13 13:19:52 UTC
Permalink
Post by Sam Wormley
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Survey quality GPS
http://www.trimble.com/news/052198a.htm
http://www.trimble.com/gps/mteverest.html
Or with older technology, try reading

"The Great Arc: The Dramatic Tale of How India Was Mapped and Everest
Was Named"
by John Keay

http://www.amazon.com/exec/obidos/tg/detail/-/0060195185/104-8890510-0299916?v=glance
Sam Wormley
2003-10-13 14:13:45 UTC
Permalink
Post by Richard Herring
Post by Sam Wormley
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Survey quality GPS
http://www.trimble.com/news/052198a.htm
http://www.trimble.com/gps/mteverest.html
Or with older technology, try reading
"The Great Arc: The Dramatic Tale of How India Was Mapped and Everest
Was Named"
by John Keay
http://www.amazon.com/exec/obidos/tg/detail/-/0060195185/104-8890510-0299916?v=glance
There was a NOVA program devoted to that survey!
tj Frazir
2003-10-14 02:50:27 UTC
Permalink
Altimeter. usa air pressure .
GPS wount give altitude . Radar will.
Sam Wormley
2003-10-14 03:36:01 UTC
Permalink
Post by tj Frazir
Altimeter. usa air pressure .
GPS wount give altitude . Radar will.
See: http://edu-observatory.org/gps/height.html
Jim
2003-10-14 03:39:12 UTC
Permalink
Post by tj Frazir
Altimeter. usa air pressure .
GPS wount give altitude .
Why not?
Could you please explain?

Thanks.

Jim
Post by tj Frazir
Radar will.
Sam Wormley
2003-10-14 03:41:53 UTC
Permalink
Post by Jim
Post by tj Frazir
Altimeter. usa air pressure .
GPS wount give altitude .
Why not?
Could you please explain?
Thanks.
Jim
Jim, you should know better that to believe anything (tj Frazir) writes!
http://edu-observatory.org/gps/tutorials.html
Jim
2003-10-14 05:29:00 UTC
Permalink
Post by Sam Wormley
Post by Jim
Post by tj Frazir
Altimeter. usa air pressure .
GPS wount give altitude .
Why not?
Could you please explain?
Thanks.
Jim
Jim, you should know better that to believe anything (tj Frazir) writes!
http://edu-observatory.org/gps/tutorials.html
While I enjoy learning about physics from reading replies from
yourself and others here, my participation must be restricted, due to
my lack of education.

I enjoy a little give and take with tj, Spaceman, etc., to fill the
conversation void. Posting questions, like above, is just my way of
feeling a-part-of. The first few replies, before the cursing and
whining set in, are kind of entertaining. As long as you don't ask for
any real facts, or references, the conversation stays pretty civil.

As for believing people's posts. It's never hard to tell the
difference between information gleaned from years of hard work, and
well, the other stuff.

I still have a few questions on some subjects, that I'll post on every
now and then. I just need to space 'em out so's not to try the
patience of those in the know. I'll get back on my 'acceleration'
education in another few days. I need to get clearer on what I'm
trying to ask.

Thanks for the link. They all get visited and added to Favorites. :)

Jim
MorituriMax
2003-10-14 05:37:56 UTC
Permalink
Post by Sam Wormley
Post by Jim
Post by tj Frazir
Altimeter. usa air pressure .
GPS wount give altitude .
Why not?
Could you please explain?
Thanks.
Jim
Jim, you should know better that to believe anything (tj Frazir) writes!
Obviously tj hasn't had a heart to heart with his boss yet. Heh

MorituriMax
2003-10-14 04:00:44 UTC
Permalink
Altimeter.. .. ..
BS Filter Activated.
Dirk Van de moortel
2003-10-12 13:27:21 UTC
Permalink
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Mainly by careful triangulation (before GPS we also knew Everest's
height).
Note that 'sealevel' is in fact sort of average sealevel, and also note
that two neighbouring countries can decide on different average
sealevels for the same sea :-)

Interesting read: Geodesy for the Layman:
http://www.nima.mil/GandG/geolay/toc.htm

Dirk Vdm
Uncle Al
2003-10-12 15:48:10 UTC
Permalink
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Classically, you define the geoid and survey the mountain. In the
21st century, you define the geoid (World Geodetic Survey 1984) and do
high accuracy integrated GPS. The answers agree to less than a meter
noise.

Note that plumb lines in the Himalayas do *not* point toward the
center of the Earth, and by a serious surveying offset even allowing
for the horizontal component of Coriolus force. It's all that mass
asymmetrically arrayed around the bob what does it. Ya gotta know
what you are doing. GPS removes all of that bother - after the
satellite orbits are corrected for gravity variation. India is
sitting atop the major negative gravity anomaly of the planet.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Robert J. Kolker
2003-10-12 15:57:12 UTC
Permalink
Post by Uncle Al
satellite orbits are corrected for gravity variation. India is
sitting atop the major negative gravity anomaly of the planet.
Ah ha! So that is how they do the Rope Trick.

Bob Kolker
Graham Lee
2003-10-12 17:30:59 UTC
Permalink
Post by Uncle Al
In the
21st century, you define the geoid (World Geodetic Survey 1984)
Or just use a value from the previous century.... ^^^^
Jim
2003-10-14 00:48:36 UTC
Permalink
Post by Kamath Raj
hai,
we say that Mt.Everest is 8848m high.But how do we measure it?
Also we say that a place 'x' is at a height of 'y' meters from the sea
level.How can we really measure that practically?.Can u plz tell me
how?
Use a friend, a transit, a shot-stick, and a lot of walking/climbing.

Jim
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