"Toller" wrote:

You are not really into geometry, are you?
http://en.wikipedia.org/wiki/Non-euclidian_geometry

That was my initial reaction, but on reflection, the definition of
parallel lines is not different in the three geometries, just the
number of parallel lines.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

CW wrote:

Parallel has only one definition. It's not open to interpretation. You're a
Bill Clinton fan, aren't you?

Parallel - each point on line A equidistant from its counterpart on
Line B
- in plane (as in two dimensions) geometry. In 3-D things get a bit
trickier,
double helix for example - pairs of points equidistant but the
"lines" aren't
straight. Euclidian and Non Euclidean geometry have different sets
of
Theoroms and Axioms. And when you want to play in "n" dimensions
Analytical Geometry is pretty handy. You can describe a closed shape
that
has an infinite surface are and no volume and another that has
infinite
volume but no surface are. The mobius strip has either no outside
surface
or no inside surface. Besides, we don't live on a plane but rather
more or
less of a sphere - and we're basically stuck operating on or above
the
surface. Then there's Einstein's "deformed/curved space" idea that
raises all kinds of hell with plane geometry.

charlie b

Fri, Apr 20, 2007, 10:46am (EDT-3) (GROVER)
physics us with:
The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

Maybe. Unless the wind is blowing.

However, you left out too many pertinent details to give an
absolute answer:
How long are the plumb bob strings?
Are the strings the same length?
What are the strings attached to?
What type of knots were used?
Were both strings tied with the same type of knot?
Are both strings attached at the same level?
Can you see both plumb bobs at the same time?

When you can provide answers to these questions, then you can
receive a viable response to your original question. Unless more
questions come up in the meantime that is. Next time properly research
your questions, before you ask them.



JOAT
Expensive tennis shoes won't cure a sore toe.
- Bazooka Joe

In article .com,
GROVER wrote:
...snipped...
The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


No, they have to be approximately 12,500 miles apart for that.


--
When the game is over, the pawn and the king are returned to the same box.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar.org

"charlieb" wrote in message
...
Now about those space ships approaching each other
at the speed of light and both turn on their headlights
- could either pilot/dirver see the on coming vehicle's
lights?


I just had a vision of the alien guy from Mars wearing the Spartan helmet on
the TV cartoon. ;~) Bugsbunny IIRC

Thanks for that one.

On Apr 21, 1:51 am, (J T) wrote:
Fri, Apr 20, 2007, 10:46am (EDT-3) (GROVER)
physics us with:
The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

Maybe. Unless the wind is blowing.

However, you left out too many pertinent details to give an
absolute answer:
How long are the plumb bob strings?
Are the strings the same length?
What are the strings attached to?
What type of knots were used?
Were both strings tied with the same type of knot?
Are both strings attached at the same level?
Can you see both plumb bobs at the same time?

The weight, material and shape of the BOBs come into play in a windy
model. Or not.
Either way, plug in all the info, wind up the ol' 'puter out comes the
answer and BOB is your uncle.

efgh wrote:
"GROVER" wrote in message
oups.com...
Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


I would say they are as close to parallel as one would care for them to be.
If you want to get technical, they are not exactly parallel due to the
curvature of the earth. One would assume that the bottom of the plumb bob
is pointing at the exact centre of the earth due to gravity and since we're
on a ball, they wouldn't be exactly parallel. At 50 feet apart, the
difference wouldn't be enough to care about.


I was in HS when they built the Verrazano Bridge in NY. I remember one
of my teachers explaining that the uprights had to be 6" out of parallel
due to the curvature of the earth. I don't know if the number is
accurate, but that is what I recall (after forty years or so).

Glen

In article .net,
Glen wrote:

efgh wrote:
"GROVER" wrote in message
oups.com...
Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


I would say they are as close to parallel as one would care for them to be.
If you want to get technical, they are not exactly parallel due to the
curvature of the earth. One would assume that the bottom of the plumb bob
is pointing at the exact centre of the earth due to gravity and since we're
on a ball, they wouldn't be exactly parallel. At 50 feet apart, the
difference wouldn't be enough to care about.


I was in HS when they built the Verrazano Bridge in NY. I remember one
of my teachers explaining that the uprights had to be 6" out of parallel
due to the curvature of the earth. I don't know if the number is
accurate, but that is what I recall (after forty years or so).

Glen

Let's do some quick math.

The towers are about 700 feet tall, and the Earth's radius is about 4000
miles. 700 feet / 4000 miles is about 1 part in 30,000.

Since arc length is proportional to radius, the tops of the towers are 1
part in 30,000 further apart from each other than their bases. The towers
are about a mile (call it 5000 feet) apart, so the tops are about 5000 /
30,000, or 1/6 of a foot further apart than the tops. Call it two inches.

Now, let's got to the video tape. Wikipedia says:

Due to the height of the towers (690') and their distance apart (4260'), the
curvature of the earth's surface had to be taken into account when designing
the bridge -- the towers are 1-5/8 inches farther apart at their tops than at
their bases.

Not bad for back of the envelope, huh?

"Roy Smith" wrote in message
...
In article .net,
Glen wrote:

efgh wrote:
"GROVER" wrote in message
oups.com...
Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


I would say they are as close to parallel as one would care for them to
be.
If you want to get technical, they are not exactly parallel due to the
curvature of the earth. One would assume that the bottom of the plumb
bob
is pointing at the exact centre of the earth due to gravity and since
we're
on a ball, they wouldn't be exactly parallel. At 50 feet apart, the
difference wouldn't be enough to care about.


I was in HS when they built the Verrazano Bridge in NY. I remember one
of my teachers explaining that the uprights had to be 6" out of parallel
due to the curvature of the earth. I don't know if the number is
accurate, but that is what I recall (after forty years or so).

Glen

Let's do some quick math.

The towers are about 700 feet tall, and the Earth's radius is about 4000
miles. 700 feet / 4000 miles is about 1 part in 30,000.

Since arc length is proportional to radius, the tops of the towers are 1
part in 30,000 further apart from each other than their bases. The towers
are about a mile (call it 5000 feet) apart, so the tops are about 5000 /
30,000, or 1/6 of a foot further apart than the tops. Call it two inches.

Now, let's got to the video tape. Wikipedia says:

Due to the height of the towers (690') and their distance apart (4260'),
the
curvature of the earth's surface had to be taken into account when
designing
the bridge -- the towers are 1-5/8 inches farther apart at their tops
than at
their bases.

Not bad for back of the envelope, huh?

You're a star.

Patriarch writes:

"Leon" wrote in news:4ObWh.5794$H_5.4139
@newssvr23.news.prodigy.net:


"GROVER" wrote in message
oups.com...
Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


No.


According to which theory?

String Theory

"Leon" writes:

"GROVER" wrote in message
oups.com...
Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?


No.

Second question - How far apart are the values?

Roy Smith writes:

Let's do some quick math.

The towers are about 700 feet tall, and the Earth's radius is about 4000
miles. 700 feet / 4000 miles is about 1 part in 30,000.

Since arc length is proportional to radius, the tops of the towers are 1
part in 30,000 further apart from each other than their bases. The towers
are about a mile (call it 5000 feet) apart, so the tops are about 5000 /
30,000, or 1/6 of a foot further apart than the tops. Call it two inches.
[snip]

Not bad for back of the envelope, huh?

Ding Ding Ding Ding. We have a winnah!

On Apr 20, 1:54 pm, "efgh" wrote:
"GROVER" wrote in message

oups.com...

Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

I would say they are as close to parallel as one would care for them to be.
If you want to get technical, they are not exactly parallel due to the
curvature of the earth. One would assume that the bottom of the plumb bob
is pointing at the exact centre of the earth due to gravity and since we're
on a ball, they wouldn't be exactly parallel. At 50 feet apart, the
difference wouldn't be enough to care about.

Also, the plumb bobs contain mass, and exert gravitational attraction
upon each other. That would further take the strings out of
parallel.

On 20 Apr 2007 10:46:22 -0700, GROVER
wrote:

Since I've been enjoying the topics and discussions of this news
group, and I see that there are many posters who are quite bright, I
decided to pose a question concerning the laws of physics to
stimulate the group's curiosity.

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

Technically - no.

For single story building construction - close enough ;-)

John

On Apr 21, 7:58 am, (Larry W) wrote:
In article .com,GROVER wrote:

...snipped...

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

No, they have to be approximately 12,500 miles apart for that.

Or one directly over the other.

On Apr 21, 7:58 am, (Larry W) wrote:
In article .com,GROVER wrote:

...snipped...

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

No, they have to be approximately 12,500 miles apart for that.



??

The question is: If you hang two plumb bobs, say 50 feet apart are the
strings parallel?

No, they have to be approximately 12,500 miles apart for that.



??


I think we're picking fly **** out of the black pepper once again.

Plumb bobs in use are never parallel unless one is inside the other ... in
which case they would be coaxial as well. In our imperfect world, they're
often close enough to being parallel as not to cause us worry. That doesn't
stop the pepper pickers however.

Go make some sawdust.

"CW" wrote in message
news

"Toller" wrote in message
...

No way to answer this question without knowing your definition of
"parallel".

Parallel has only one definition. It's not open to interpretation. You're
a
Bill Clinton fan, aren't you?

That depends on what your definition of the word "fan" is.

B.

"Buddy Matlosz" wrote in message
...

"CW" wrote in message
news

"Toller" wrote in message
...

No way to answer this question without knowing your definition of
"parallel".

Parallel has only one definition. It's not open to interpretation.
You're
a
Bill Clinton fan, aren't you?

That depends on what your definition of the word "fan" is.

B.

GROVER wrote:

| Since I've been enjoying the topics and discussions of this news
| group, and I see that there are many posters who are quite bright, I
| decided to pose a question concerning the laws of physics to
| stimulate the group's curiosity.
|
| The question is: If you hang two plumb bobs, say 50 feet apart are
| the strings parallel?

Since you make it a physics question rather than a woodworking
question, the answer is that two separate strings can never be
parallel.

"The proof is left as an exercise for the student." :-)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/

Han wrote:

| Actually it depends on the mass of the plumb bobs. If massive
| enough they would attract each other.

Just to add aggravation: the /strings/ will attract each other...

....and both the strings and the bobs will share a mutual attraction
with every other object in (at least) /this/ universe.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/

On Apr 22, 10:33 am, "Morris Dovey" wrote:
GROVER wrote:

| Since I've been enjoying the topics and discussions of this news
| group, and I see that there are many posters who are quite bright, I
| decided to pose a question concerning the laws of physics to
| stimulate the group's curiosity.
|
| The question is: If you hang two plumb bobs, say 50 feet apart are
| the strings parallel?

Since you make it a physics question rather than a woodworking
question, the answer is that two separate strings can never be
parallel.

"The proof is left as an exercise for the student." :-)


If the 'strings' are mere physical props for something bigger, such as
the imaginary line between two points, one would have to address the
question: "why strings?"
In an equation, one can force the issue that they are perfectly
parallel and bend the universe around them to make it fit. Simply
metaphysics, really. To me those strings are perfectly parallel and
what is anybody going to do about it?
Other than that, I bolt onto Rick M's black pepper theory... or as
they say on an Eastern mountaintop in Nepal, and I translate loosely:
"no need to sort mosquito turds by size."

r

Robatoy wrote:

| If the 'strings' are mere physical props for something bigger, such
| as the imaginary line between two points, one would have to address
| the question: "why strings?"

Indeed - or even "why plumb bobs?" or "why pepper?" ;-)

| In an equation, one can force the issue that they are perfectly
| parallel and bend the universe around them to make it fit. Simply
| metaphysics, really. To me those strings are perfectly parallel and
| what is anybody going to do about it?

I'm willing to agree without reservation as soon as you post the
equations that accounts for the effect of all other masses to which
the strings and bobs are attracted. The equations will, of course, be
different for each (string,bob) pair...

I'm not sure what anyone else is going to do about it, but I'm going
to go have lunch. :-)

| Other than that, I bolt onto Rick M's black pepper theory... or as
| they say on an Eastern mountaintop in Nepal, and I translate
| loosely: "no need to sort mosquito turds by size."

....nor moonbeams by pitch.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/

Robatoy wrote:

snip

as they say on an Eastern mountaintop in Nepal,
and I translate loosely:

waiting with great anticipation for
the Eastern Words of Wisdom...

"no need to sort mosquito turds

by size."

Huh?

What about shapes or weight - or colors?

Oh.

Ah - so!

charlie b