dixon wrote:
I have a question that has me questioning the laws of fluid physics. I will
be posting the question in a day or so, but first I want to get some others
input regarding water pressure at different depths. First, do we all agree
that pressure is only dependant on depth of water? Lets say you had an
aquarium that was 3 feet high and 3 feet long and 2 feet front to back.
Fluid laws say it would not matter what the front to back measurement is.
The pressure on the front glass would be the same if the back of the
aquarium was two feet or 200 feet or 200 miles away, right?
Dixon
--



Yes:-)

K

"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam doesn't matter
...
but ... then why are dams so thick at the top? Dams can be 20 / 30 / ...
feet thick at the top where the water is only a few inches deep. There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage heavy
equipment
if need be for repairs, etc. That will require a certain practical width.
You
also need some structural mass to frame spillway gates, etc- often
located
near
the top of the dam. Hoover Dam has a highway across the top, and so is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of material
WRT strength. (like a roof truss)

Inspection galleys, equipment areas, and
there are also waves hitting the top above normal water level. These have
a
side force.

"P.Fritz" wrote in message ...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam doesn't matter
...
but ... then why are dams so thick at the top? Dams can be 20 / 30 / ...
feet thick at the top where the water is only a few inches deep. There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage heavy
equipment
if need be for repairs, etc. That will require a certain practical width.
You
also need some structural mass to frame spillway gates, etc- often
located
near
the top of the dam. Hoover Dam has a highway across the top, and so is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be 20 / 30 /
....
feet thick at the top where the water is only a few inches deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage heavy
equipment
if need be for repairs, etc. That will require a certain practical
width.
You
also need some structural mass to frame spillway gates, etc- often
located
near
the top of the dam. Hoover Dam has a highway across the top, and so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

Dam's are also thick, in case water rises above the top. Avoids erosion
causing breaks. Also, you may have to have a thick section not too far
down. Freshwater is about 15 psi for every 33', and the gradual decrease
to the top, will make for thicker top.

"Calif Bill" wrote in message
nk.net...

"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be 20 / 30
/
...
feet thick at the top where the water is only a few inches deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage heavy
equipment
if need be for repairs, etc. That will require a certain practical
width.
You
also need some structural mass to frame spillway gates, etc- often
located
near
the top of the dam. Hoover Dam has a highway across the top, and so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

Dam's are also thick, in case water rises above the top. Avoids erosion
causing breaks. Also, you may have to have a thick section not too far
down. Freshwater is about 15 psi for every 33', and the gradual decrease
to the top, will make for thicker top.

Asslicker shows his lack of reading comprehension once again......and
maintains his deathgrip on the title of King of the NG idiots.

"Calif Bill" wrote in message ink.net...
"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be 20 / 30 /
...
feet thick at the top where the water is only a few inches deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage heavy
equipment
if need be for repairs, etc. That will require a certain practical
width.
You
also need some structural mass to frame spillway gates, etc- often
located
near
the top of the dam. Hoover Dam has a highway across the top, and so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

Dam's are also thick, in case water rises above the top. Avoids erosion
causing breaks. Also, you may have to have a thick section not too far
down. Freshwater is about 15 psi for every 33', and the gradual decrease
to the top, will make for thicker top.

Also, usually, the bottom of the dam is restrained by rock, while the
top of the dam is restrained only at the ends.

"basskisser" wrote in message
om...
"Calif Bill" wrote in message
ink.net...
"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam
doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be 20 /
30 /
...
feet thick at the top where the water is only a few inches deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage
heavy
equipment
if need be for repairs, etc. That will require a certain
practical
width.
You
also need some structural mass to frame spillway gates, etc-
often
located
near
the top of the dam. Hoover Dam has a highway across the top, and
so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

Dam's are also thick, in case water rises above the top. Avoids erosion
causing breaks. Also, you may have to have a thick section not too far
down. Freshwater is about 15 psi for every 33', and the gradual
decrease
to the top, will make for thicker top.

Also, usually, the bottom of the dam is restrained by rock, while the
top of the dam is restrained only at the ends.

What does this have to do with the question. You would only need thickness
at the ends if this was the reason. You could save cost via material and
material moving with a thin center top.

"Calif Bill" wrote in message link.net...
"basskisser" wrote in message
om...
"Calif Bill" wrote in message
ink.net...
"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam
doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be 20 /
30 /
...
feet thick at the top where the water is only a few inches deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to stage
heavy
equipment
if need be for repairs, etc. That will require a certain
practical
width.
You
also need some structural mass to frame spillway gates, etc-
often
located
near
the top of the dam. Hoover Dam has a highway across the top, and
so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported compression?
Axial supported compression? Tension? Compression perpendicular to the
plane?

Dam's are also thick, in case water rises above the top. Avoids erosion
causing breaks. Also, you may have to have a thick section not too far
down. Freshwater is about 15 psi for every 33', and the gradual
decrease
to the top, will make for thicker top.

Also, usually, the bottom of the dam is restrained by rock, while the
top of the dam is restrained only at the ends.

What does this have to do with the question.

Everything, but, depending on WHICH question you'd like answered.

You would only need thickness
at the ends if this was the reason.

Nope, absolutely wrong. I simply said the bottom is restrained by
rock, usually, or in the case of earthen dams, even skin friction.
This is true. AND, it also has no bearing on the thickness in the
middle, completely different set of circumstances, or in a way you may
understand, apples, and oranges.

You could save cost via material and
material moving with a thin center top.

Again, why would you assume that, because the bottom of a dam is
restrained by mechanical means, either rock strata, skin friction,
caissons, etc., that that somehow means there are smaller forces
acting on the "center top"???

"basskisser" wrote in message
m...
"Calif Bill" wrote in message
link.net...
"basskisser" wrote in message
om...
"Calif Bill" wrote in message
ink.net...
"basskisser" wrote in message
m...
"P.Fritz" wrote in message
...
"Calif Bill" wrote in message
ink.net...

"Gould 0738" wrote in message
...
I would have agreed with the width/length of the tank/dam
doesn't
matter
...
but ... then why are dams so thick at the top? Dams can be
20 /
30 /
...
feet thick at the top where the water is only a few inches
deep.
There
is
more to this than me thinks!


Many dams have a service road across the top, a place to
stage
heavy
equipment
if need be for repairs, etc. That will require a certain
practical
width.
You
also need some structural mass to frame spillway gates, etc-
often
located
near
the top of the dam. Hoover Dam has a highway across the top,
and
so
is
probably
75 feet "thick" many feet above the surface. :-)


And parts of the dam are hollow.

Because a solid mass is not necessarily the most efficient use
of
material
WRT strength. (like a roof truss)

Hmm, really? When speaking of "strength", just what aspect are you
talking about, Fritz? Stress? Strain? Axial unsupported
compression?
Axial supported compression? Tension? Compression perpendicular to
the
plane?

Dam's are also thick, in case water rises above the top. Avoids
erosion
causing breaks. Also, you may have to have a thick section not too
far
down. Freshwater is about 15 psi for every 33', and the gradual
decrease
to the top, will make for thicker top.

Also, usually, the bottom of the dam is restrained by rock, while the
top of the dam is restrained only at the ends.

What does this have to do with the question.

Everything, but, depending on WHICH question you'd like answered.

You would only need thickness
at the ends if this was the reason.

Nope, absolutely wrong. I simply said the bottom is restrained by
rock, usually, or in the case of earthen dams, even skin friction.
This is true. AND, it also has no bearing on the thickness in the
middle, completely different set of circumstances, or in a way you may
understand, apples, and oranges.

You could save cost via material and
material moving with a thin center top.

Again, why would you assume that, because the bottom of a dam is
restrained by mechanical means, either rock strata, skin friction,
caissons, etc., that that somehow means there are smaller forces
acting on the "center top"???

You're babbling again, and you are not a brook.

"dixon" wrote in message news:JqOqd.110213$V41.105580@attbi_s52...
I have a question that has me questioning the laws of fluid physics. I will
be posting the question in a day or so, but first I want to get some others
input regarding water pressure at different depths. First, do we all agree
that pressure is only dependant on depth of water? Lets say you had an
aquarium that was 3 feet high and 3 feet long and 2 feet front to back.
Fluid laws say it would not matter what the front to back measurement is.
The pressure on the front glass would be the same if the back of the
aquarium was two feet or 200 feet or 200 miles away, right?
Dixon
--

So far, 12-03-04, everyone has agreed but I don't know... water
pressure might be x at so many feet depth but that is water pressure
from all sides pushing in or out on a gauge. In the above situation
the outside of the aquarium is not under pressure and it would seem
that at a constant depth the more water that was inside, as in a
bigger aquarium, it would add more and more weight and therefore more
pressure on the sides. But, then again, that kid did plug the dike
with just his finger.