Spehro Sez: "Acceleration depends on the force and the mass (a = f/m). The
net force is the force from gravity minus the drag from the air. Obviously
at the terminal velocity the acceleration is zero."

A fine point for sure! But acceleration is, as you said = force/mass. Not
sure if you meant to say that air drag has an influence on acceleration from
the force of gravity. I don't think it does. Air drag will effect the
resulting velocity, but acceleration from gravity is a constant.

Bob Swinney


"Spehro Pefhany" wrote in message
...
On Tue, 16 Dec 2003 19:43:23 GMT, the renowned "Bob Swinney"
wrote:

Ted sez: "32 ft/sec^2 "near" Earth's surface in vacuum"

Forget the vacuum, Ted. Acceleration is independent of ambient
conditions.
*Terminal velocity* is related to the medium through which a body
"accelerates". Acceleration varies slightly with altitude (on earth)
with
32 ft sec-sec being the accepted figure for sea level.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers:
http://www.trexon.com
Embedded software/hardware/analog Info for designers:
http://www.speff.com

Randal O'Brian wrote:
"Roy" wrote in message
...
I have heard on numerous occasion that a penny thrown off the top
observation tower of thr Empire State building can hit the ground
with enough force to crack a 6" concrete slab. I used to believe
this statement when I was a kid, but have a hard time buying it as
fact now. I just can't see it being fact, and see it more of an old
wives type tale. I don;t really think you could throw a penny that
hard and far enough to make it reach out sufficiently to clear the
lower floors stepped out structure anyhow.


A month or so ago, the MythBusters on the Discovery Channel tested
the penny legend and determined that the terminal velocity of a penny
tossed off the Empire state Bldg was about 60 MPH, as I recall.
There is not enough kinetic energy in a penny at that speed to do
much damage.

Randy

But I was told by a former high-rise construction worker that a bolt dropped
from an upper floor on a supervisor walking on the ground floor can do some
damage.

(Stan Schaefer) wrote in message . com...


If you guys haven't caught Mythbusters, it's about debunking urban
myths. Some of the stuff that's shown so far has been about the guy
in the lawn chair and the weather balloons,

Is that really a myth? I've seen pictures of the guy, and in the
aviation business, of which I'm a part, we heard a lot about it. If
it's a legend, it's a good one.
Dan

Ted Edwards wrote:
wrote:
Ted Edwards wrote:

Bob Swinney wrote:
Fire a cannon ball exactly horizontal (level) with the earth. At
the exact instant the cannon ball leaves the muzzle, drop another
cannon ball from the same height. The 2 cannon balls will reach
the earth at the same time.

On an airless planet but not on Earth. Think Areodynamic drag.

Even on earth.

Nope.

Basic physics has us break things up into components.

This is frequently the case and examples in high school Physics have
carefully chosen conditions so this will be ok. In order to do so, we
apply the principle of superposition which requires that the total
effect of a set of forces is the sum of the effects of the individual
forces. This requires linearity. Drag is proportional to velocity
squared.

Set up the differential equations of motion for a projectile fired at
some angle to the horizontal in a vertical gravitational field and
experiencing a retarding force alligned with but in opposite direction
to the motion vector that is proportional to the magnitude of the
velocity squared. It's a neat problem and fun to work. (I first did
it studying arrow flight.) You will discover two things: 1) The
resulting set of differential equations has no closed form solution
(elliptic integrals) and must therefore be solved numerically.
(Runge-Kutta is a good method if you wish to try it.) 2) Attempting
to separate the forces into vertical and horrizontal components gives
an approximation of variable quality but is, in fact, wrong.
Speaking vaguely, since the aerodynamic forces depend on the square
of velocity, a change in horizontal velocity affects vertical as well
as horizontal force and vice versa.

Ted

Particularly in the extreme case of a bullet fired a few feet above the
ground horizontally.

On 16 Dec 2003 16:55:52 -0800, jim rozen
brought forth from the murky depths:

In article , Jeff Wisnia says...

http://www.snopes.com/spoons/noose/balloon.htm

"As Larry and his lawnchair drifted into the approach path to
Long Beach Municipal Airport, perplexed pilots from two passing
Delta and TWA airliners alerted air traffic controllers about
what appeared to be an unprotected man floating through the sky in a
chair."

Damn I wish they had saved the tapes of those conversations
between the controllers and the flight crews. Now *that*
would be priceless stuff.

My grandfather was fascinated by this event. We have a
photo of him on his 90th birthday, sitting in our yard
in an aluminum lawn chair. With about 20 helium balloons
tied to it!

When my grandfater was 93, the California Highway Patrol followed
him home one day from Interstate 5 in L.A. and warned my grandmother
to watch him so he would keep that 3-wheeled bicycle of his OFF THE
FREEWAY. He decided that the freeway was the shortest route home
that day.


---
- Sarcasm is just one more service we offer. -
http://diversify.com Web Applications

jim rozen wrote:

32 ft/sec^2 "near" Earth's surface in vacuum.

32 = 33 for large values of 32.

To slide rule accuracy. :-)

BTW, it's "vacuum" that's the key word.

Ted

SimonShabtai Evan wrote:

Also note that these calcuations (from Physics 101; Halliday and
Resnick/Wiley and Sons Inc) do not include atmospheric losses.

But that is a poor approximation for a realistic balistic situation.

Ted

Bob Swinney wrote:

Spehro Sez: "Acceleration depends on the force and the mass (a = f/m). The
net force is the force from gravity minus the drag from the air. Obviously
at the terminal velocity the acceleration is zero."

A fine point for sure! But acceleration is, as you said = force/mass. Not
sure if you meant to say that air drag has an influence on acceleration from
the force of gravity. I don't think it does. Air drag will effect the
resulting velocity, but acceleration from gravity is a constant.

An object, for simplicity, falling straight down in still air has two
forces acting on it, the force of gravity, m/g, and the force of
aerodynamic friction. These will act in opposite directions and will be
equal at terminal velocity.

Ignoring this will just confuse you.

Ted

Ignoring this will just confuse you.

Maybe, Ted, but *acceleration* from gravity is not diminished in any way.
At each instant, dt, acceleration is still present. The result is offset by
the drag of the air and a sort of equilibrium seems to exist, but
acceleration from gravity is constant. Matter of fact you and I are
accelerating right now toward the center of the earth - but our movement is
arrested by offsetting forces. Nevertheless, at any given instant, dt, we
are accelerating.

Bob Swinney

"Ted Edwards" wrote in message
...
Bob Swinney wrote:

Spehro Sez: "Acceleration depends on the force and the mass (a = f/m).
The
net force is the force from gravity minus the drag from the air.
Obviously
at the terminal velocity the acceleration is zero."

A fine point for sure! But acceleration is, as you said = force/mass.
Not
sure if you meant to say that air drag has an influence on acceleration
from
the force of gravity. I don't think it does. Air drag will effect the
resulting velocity, but acceleration from gravity is a constant.

An object, for simplicity, falling straight down in still air has two
forces acting on it, the force of gravity, m/g, and the force of
aerodynamic friction. These will act in opposite directions and will be
equal at terminal velocity.


Ted

Dave Mundt wrote:
cannon from a tree trunk (OMWC - Blacksmith making hoops for strength
and applying them hot).

I was singularly underwhelmed by that technique. I noticed they not only
applied them hot, but fumbled a rivet into them from the wood side while
doing so. This of course means the rivet couldn't be set properly (with
the wood for a backup) and the band burnt away the very wood it was
supposed to be buttressing.

The right way to band a trunk would be to do what coopers do: drive the
bands on after they're made and rivited. All they need is to adze a bit
of taper into the trunk to make that easier. AND that would have avoided
a lot of toxic smoke.

As for making one in one day ... no doubt in my mind that it can be done.
For one thing, the auger was probably driven by horsepower, and the
pressure was probably applied by leverage. After all, we use drill
presses which act in precisely the same way in principle.

They may be cool, but they are largely fools in some respects ... I saw
one of them burn off an eyebrow and most of his hair *and* get flash
burns while fooling with gasoline vapors, and he was so lacking in pride
as to let that be shown in the episode. Also, they make mistakes in fact.
The Cola episode is a case in point. CC is actually an excellent fluid to
use on rusted fasteners; I've seen it loosen muffler clamp bolts that
were just about solidy corroded on.



Regards, Hoyt McKagen

To prevent virus propogation, please don't put this addy in your book
Belfab CNC - http://belfab.freeyellow.com/belfab.html
Best MC - http://batwings.freeyellow.com/best.html
Camping/Caving - http://batwings.freeyellow.com/caving.html
Two-Wheel-Tech List - http://batwings.freeyellow.com/2whfaq.html
It's called 'Mad Cow Disease' because 'PMS' was already taken.

In article ,
Ted Edwards wrote:
SimonShabtai Evan wrote:

Also note that these calcuations (from Physics 101; Halliday and
Resnick/Wiley and Sons Inc) do not include atmospheric losses.

But that is a poor approximation for a realistic balistic situation.

Not if you can provide an adequately sized cylinder of vacuum
from the rifle up to the zero-velocity point and back down. :-)

Granted -- with air in the equation, it makes a *big*
difference.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Tue, 16 Dec 2003 13:12:11 GMT, "Pablo" wrote:

Regardless of weight, a falling body will accelerate at 33 ft. per second,
per second.

Oh darn! That'll be seriously bad news to parachutists.

Bet ya don't see snowflakes accelerating at that rate.

On Tue, 16 Dec 2003 11:17:13 GMT, Gunner
wrote:


Which brings to mind a story about a party, the neighbors Pekinese
(sp?) a tall fence and a miss thrown lawn dart. Not for the
squeemish.

Roger that. Revolting waste of good muskie bait,

On Wed, 17 Dec 2003 04:39:59 GMT, "Bob Swinney"
wrote:

Ignoring this will just confuse you.

Maybe, Ted, but *acceleration* from gravity is not diminished in any way.
At each instant, dt, acceleration is still present. The result is offset by
the drag of the air and a sort of equilibrium seems to exist, but
acceleration from gravity is constant. Matter of fact you and I are
accelerating right now toward the center of the earth - but our movement is
arrested by offsetting forces. Nevertheless, at any given instant, dt, we
are accelerating.

Acceleration is, by definitition, rate of change of velocity with
time AKA dv/dt. If me arse is changing velocity at the moment I
sure don't notice it.

Gravity is a force proportional to mass which makes it acceleration in
terms of math units, but that only becomes dv/dt in a force equation
after other forces like restraint ( the stool me arse is perched on)
and viscous or aerodynamic drag that impedes the descent of
snowflakes, parachutists, and other falling objects is included.

Hatchers Notebook (a monstrous book available from Amazon or the
library) has a section on this, including tests. Aerodynamic drag
plays a big part.
Having said that, I wouldn't stand under falling bullets.
Geoff

On Tue, 16 Dec 2003 18:35:23 GMT, "Ed Huntress" wrote:
Tumbling which way? Bullets tumble when they lose a percentage of their rpm.
Bullets shot straight up always tumble. There go the old aerodynamics...

That's not what Hatcher reported. The bullets came down base first, and
still spinning at a great rate.

Gary

Don sez:

"Acceleration is, by definitition, rate of change of velocity with
time AKA dv/dt. If me arse is changing velocity at the moment I
sure don't notice it."

That's because you aren't (we aren't) finely tuned enough to notice the
teensy-tiny interval dv/dt. grin

Bob Swinney





"Don Foreman" wrote in message
...
On Wed, 17 Dec 2003 04:39:59 GMT, "Bob Swinney"
wrote:

Ignoring this will just confuse you.

Maybe, Ted, but *acceleration* from gravity is not diminished in any way.
At each instant, dt, acceleration is still present. The result is offset
by
the drag of the air and a sort of equilibrium seems to exist, but
acceleration from gravity is constant. Matter of fact you and I are
accelerating right now toward the center of the earth - but our movement
is
arrested by offsetting forces. Nevertheless, at any given instant, dt,
we
are accelerating.

Gravity is a force proportional to mass which makes it acceleration in
terms of math units, but that only becomes dv/dt in a force equation
after other forces like restraint ( the stool me arse is perched on)
and viscous or aerodynamic drag that impedes the descent of
snowflakes, parachutists, and other falling objects is included.

Yep! Stands to reason the rotational velocity would sustain long after
forward velocity.

Bob Swinney
"Gary Coffman" wrote in message
...
On Tue, 16 Dec 2003 18:35:23 GMT, "Ed Huntress"
wrote:
Tumbling which way? Bullets tumble when they lose a percentage of their
rpm.
Bullets shot straight up always tumble. There go the old aerodynamics...

That's not what Hatcher reported. The bullets came down base first, and
still spinning at a great rate.

Gary

Larry Jaques wrote:

snipped



When my grandfater was 93, the California Highway Patrol followed
him home one day from Interstate 5 in L.A. and warned my grandmother
to watch him so he would keep that 3-wheeled bicycle of his OFF THE
FREEWAY. He decided that the freeway was the shortest route home
that day.

Did he also complain to your grandmother that all the other damn fool
drivers were going the "wrong way" on that side of the freeway and nearly
killed him? (G)

Jeff


--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone
to place the blame on."

Don Foreman wrote:

Roger that. Revolting waste of good muskie bait,

Don, did I get this one from you?
"
Recalls a segment on a Minnesota fishing show I saw years ago, about
musky
fishing. It was on "In -Fisherman" before they were bigtime TV. Lots
of
serious stuff about locating and catching the toothy critters. Camera
panned
to a lady standing on her dock in the distance and waving her hands
frantically. Pan back to Dave and Al in the boat.

"Think we should check that out?"

"Yeah, we'd better." Start motor, run over to the lady's dock.
"What seems to be the problem, Ma'am?"

"My Fifi! My Fifi! My toy poodle was playing on the dock, and a huge
nasty
fish jumped out of the water and ate her!"

Camera pans across the many brightly-colored lures strewn about the deck
of
the boat. Up to Dave. He says, deadpan:

"What color was the dog, Ma'am?"
"
Ted

On Tue, 16 Dec 2003 19:15:03 -0600, "Paul K. Dickman"
wrote:


Jeff Wisnia wrote in message ...
Stan Schaefer wrote:



snipped



If you guys haven't caught Mythbusters, it's about debunking urban
myths. Some of the stuff that's shown so far has been about the guy
in the lawn chair and the weather balloons,

Did they claim *that* one was untrue?

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone to
place the blame on."

No, they claimed that it was easily possible, and after their test, they
received copies of reports from various agencies documenting the original
flight.

Before their test, all they got was the runaround from the various agencies
they contacted trying to obtain information and permission for their test.

Paul K. Dickman

p.s. They also said it was possible to electrocute yourself by peeing on the
third rail, but that you would have to be kneeling in a puddle, and really
have to go.



Do a Google for "Lawn Chair Larry".

andy asberry wrote:
On Tue, 16 Dec 2003 19:15:03 -0600, "Paul K. Dickman"
wrote:


Jeff Wisnia wrote in message ...

Stan Schaefer wrote:


snipped


If you guys haven't caught Mythbusters, it's about debunking urban
myths. Some of the stuff that's shown so far has been about the guy
in the lawn chair and the weather balloons,

Did they claim *that* one was untrue?

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can keep smiling when things go wrong, you've thought of someone to

place the blame on."

No, they claimed that it was easily possible, and after their test, they
received copies of reports from various agencies documenting the original
flight.

Before their test, all they got was the runaround from the various agencies
they contacted trying to obtain information and permission for their test.

Paul K. Dickman

p.s. They also said it was possible to electrocute yourself by peeing on the
third rail, but that you would have to be kneeling in a puddle, and really
have to go.




Do a Google for "Lawn Chair Larry".

Or if you really want to waste some time, check
out www.snopes.com

He was one of the ringleaders at alt.folklore.urban
while it was in it's prime.

About a year ago there was a thread on how far a bullet would travel.
Someone, Mike Graham IIRC, posted the balistics for a 22 long rifle
bullet. Since I still had that data on file, I ran it through my
balistics program for a near vertical shot. Here are the results:
-----
Given the velocity of a 22lr bullet at the muzzle and 100 yards as
1280 1017 fps respectively, I convert to metric and get
390.14m/s and 309.98m/s at muzzle and 91.44m. From these values, I
calculate the drag coefficient, km (dV/V per meter), of .002515.

Using this result and the muzzzle velocity, V0, I can calculate the
point, x1, at which the upward velocity is 0 and the point, x2, at
which the bullet has returned to the level of the muzzle. Thus,
assuming an 85 degree angle of elevation,
x1= 86.4
x2= 133.7

The positions, velocities and times at the muzzle, x1 and x2 are then

Show_flight V0 km 85 Bflight 0 x1 x2
x y Vx Vy t

0 0 34 389 0
86 729 5 0 9
134 0 1 ²61 25

Summarizing, the bullet reaches a maximum height of ~730meters where
its horizontal velocity has dropped from 34m/s to only 5m/s. Back
at the initial height, the horizontal velocity is now 1m/s, it took
almost twice as long to come down as it did to go up and its velocity
is less than 1/6 of its muzzle velocity.

Due to the complexity of the math in getting these results, the high
school physics approach to this problem ignores air friction,
i.e. sets km=0. If we do this, we get

x1= 1348.5
x2= 2697.1

Show_flight V0 0 85 Bflight 0 x1 x2
x y Vx Vy t

0 0 34 389 0
1349 7707 34 0 40
2697 0 34 ²389 79

Note that this simplified approach gives a maximum altitude over ten
times too high. Also note that without air resistance, the horizontal
velocity would remain constant, the bullet would take the same time to
come down as to go up and would be travelling at its muzzle velocity
when it got back down.

Although the "no air resistance" approach is a good introduction to
some of the concepts involved, it is not adequate to solve balistics
problems in the "real world".
---
If anyone wants the details of the calculations and can read APL, I'd be
happy to send them to you.

Ted

On Wed, 17 Dec 2003 12:28:47 -0500, Jeff Wisnia
brought forth from the murky depths:

Larry Jaques wrote:

snipped



When my grandfater was 93, the California Highway Patrol followed
him home one day from Interstate 5 in L.A. and warned my grandmother
to watch him so he would keep that 3-wheeled bicycle of his OFF THE
FREEWAY. He decided that the freeway was the shortest route home
that day.

Did he also complain to your grandmother that all the other damn fool
drivers were going the "wrong way" on that side of the freeway and nearly
killed him? (G)

No, he was just a bit senile, not Alzheimy.

P.S: You don't need to REPLY ALL when you reply, just send
your replies to the newsgroup. Most of us are smart enough
to need only one copy to comprehend it. vbg

--
Remember: Every silver lining has a cloud.
----
http://diversify.com Comprehensive Website Development

Can the New Jersey shoot straight up?

How about a 16inch round from USS New jerseyGG

--------------------------------------------------------------------------
---------------------------
John Lloyd - Cymru/Wales

On Tue, 16 Dec 2003 19:17:36 GMT, (Dave Mundt) wrote:

The results, by the by,
were that the mythbusters came to the conclusion that there was NO
way that the townsfolks could have cored a tree trunk that was eight
feet or more long in a night.

Idiots. You work it green - my whole city used to be plumbed with
wooden pipes, drilled in this manner. A few of them still get dug up
occasionally. Any half-competent green woodworker can show them how to
do it (do it green, go down the pith)

--
Smert' spamionam

In article ,
says...
Can the New Jersey shoot straight up?


Well, if the gun's stabilization was turned off and the gun was aimed to
as high an angle as possible and the ship was wallowing in a heavy,
beam-on, sea and the guy on the trigger was really good then, maybe.

But then, down below in the shop, the lathe would NOT be level! [The
Horror.....]
--
Doug d e s @ i n d i a n c h i e f d o t c o m
http://www.des.indianchief.com/index.htm

Doug Smith wrote:

In article ,
says...
Can the New Jersey shoot straight up?


Well, if the gun's stabilization was turned off and the gun was aimed to
as high an angle as possible and the ship was wallowing in a heavy,
beam-on, sea and the guy on the trigger was really good then, maybe.

But then, down below in the shop, the lathe would NOT be level! [The
Horror.....]

Firing a 16" at that much roll?
Wouldn't that present a serious danger of getting said lathe wet? Along with everything else?
--


If you try to 'reply' to me without fixing the dot, your reply
will go into a 'special' mailbox reserved for spam. See below.


--
Carl West http://carl.west.home.comcast.net

change the 'DOT' to '.' to email me

If I had six hours to chop down a tree,
I'd spend the first four sharpening the axe.
- Abraham Lincoln

On Thu, 18 Dec 2003 01:31:05 GMT, Doug Smith
brought forth from the murky depths:

In article ,
says...
Can the New Jersey shoot straight up?


Well, if the gun's stabilization was turned off and the gun was aimed to
as high an angle as possible and the ship was wallowing in a heavy,
beam-on, sea and the guy on the trigger was really good then, maybe.

But then, down below in the shop, the lathe would NOT be level! [The
Horror.....]

ROTFLMAO! I would imagine the Mess to be more of a mess, too.

--
Remember: Every silver lining has a cloud.
----
http://diversify.com Comprehensive Website Development

"George E. Cawthon" wrote in message
...


Spehro Pefhany wrote:

On Mon, 15 Dec 2003 02:23:58 GMT, the renowned "JTMcC"
wrote:

That sure doesn't sound right to me. A bullet or any other object fired
into
the air, let's say straight up to keep it simple, will slow until it
finally
stops and begins to fall back to earth. I would think the effect of
gravity
and wind resistance would determine the maximun velocity of the falling
bullet (object), not the velocity at which it was fired upward with.
The
same speed would be realized as if you had simply dropped the bullet
(object) at the same altitude from a hot air balloon. Feel free to
correct
me if I'm wrong.

Yes, provided it reaches terminal velocity from that height.
There was a recent, long and annoying thread on this in
sci.electronics.design which I considered x-posting here.. one of the
more amusing physics thought experiments was if you fired a bullet
from the imaginary surface of a stationary planet with no atmosphere
directly vertically (at less muzzle than escape velocity- no problem
with that on Earth), it would return at exactly the same speed as it
left the muzzle, in the reverse direction. Ouch.

In real conditions, if a relatively heavy bullet isn't tumbling I
could see it coming back fast enough to potentially hurt someone
(imagine, say, a 180 MPH pointy metal object falling on your skull).
But people don't always fire them straight up, which could be worse
again. There was apparently a law (called Shannon's Law) passed in
Phoenix AZ due to a youth killed from a celebratory gun firing..
common in the Hispanic community.

Gunner probably has all the facts at his fingertips on this...

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the
reward"
Info for manufacturers:
http://www.trexon.com
Embedded software/hardware/analog Info for designers:
http://www.speff.com

You don't measure bullet speed in miles per hour. But you
are pretty close to the maximum terminal velocity. 1mph =
1.467 fps so 180 mph = 264 fps. The army found that the
maximum terminal velocity of rifle bullets was about 300
mph. For comparison think of a baseball at 80 mph. If the
baseball weighs about 2.5 times the bullet, then the energy
would be the same as a bullet at 300 fps. Of course a
baseball weight many time the average rifle bullet. Or, for
another comparison, many air pistols max at about 300 fps.
So let's not get carried away with the possible damage of a
falling bullet.

I guess then, it couldn't do a lot of damage. Maybe only kill you.

STeve

"Dean" wrote in message
...
This is sort of metalwork - it involves lead. I was watching the Iraqies
celebrating the capture of Saddam by firing their rifles and guns into the
air. How dangerous are the bullets coming down ? I know they fall back
much
slower than they leave the gun barrel, but they must still be doing a fair
clip. They said 4 people so far have been killed by this but I guess in
Iraq
its hard to know which bullets came from where. As a few of you know about
guns I thought I'd ask here.

Dean.


I saw this discussion quite a while back in a gun newsgroup. People said it
was impossible, but I have read stories of it, one while I lived in New
Orleans, and the lady struck by the falling bullet died.

I guess, as Mr. George Cawthorn stated, you don't have to get overboard
about the amount of damage a falling bullet can do. It can kill you, but
probably wouldn't go through your roof or your car fender.

Steve

Mike wrote:

Can the New Jersey shoot straight up?

How about a 16inch round from USS New jerseyGG

I think it can launch cruise missiles at a high angle,
and some of the smallest guns might shoot straight up,
but the 16-inch guns have a maximum elevation of 45º.
I have a photo of a cutaway diagram of the New Jersey's
16-inch guns, that at one point says, "Guns can be inclined
individually from -5 degrees to 45 degrees, at a rate of
12-degrees per second." There are 3 turrets with 3 guns
each, 1700 tons rotating weight per turret, and basic
rounds are either 2700-pound AP or 1900-pound HC. Minimum
crew size is 77 men per turret and fire rate is two rounds
per minute per gun. The maximum range of an HC round
is "41622 yards when fired with the normal propelling
charge of 660 pounds, with a muzzle velocity of 2690 feet
per second".
-jiw

On Wed, 17 Dec 2003 10:31:18 -0500, Tom Quackenbush wrote:
Bob Swinney wrote:

Yep! Stands to reason the rotational velocity would sustain long after
forward velocity.

snip

Yes, it's still rotating, but is there enough spin remaining to
stabilize a bullet falling base first? The rifling twist is usually
chosen to impart the necessary spin to a limited range of bullet
weights within a range of speeds (relatively fast speeds, compared
with falling) for a bullet fired point first. It's counter-productive
to spin the bullet much faster than is required for normal firing
conditions.

Right, but normal firing conditions are worst case. That's because
the axis of rotation diverges from the line of flight (normal bullet
path is a parabola). This divergence allows aerodynamic forces
to disturb the gyroscopic action, causing the bullet to nutate
around the line of flight. This saps rotational energy, and causes
the bullet spin to slow faster than if the forces were aligned.

A bullet fired vertically *does* have all forces aligned. The line of
flight does line up with the spin axis. So the bullet loses rotational
energy much slower than when fired horizontally. Add to that the
bullet doesn't have to spin as rapidly to maintain stability when
the bullet is moving slowly (because the disturbing aerodynamic
forces are less). So a vertically fired bullet has the best chance
of maintaining gyroscopic stability.

Let me go out on a limb and say that sometimes the bullet remains
stable and sometimes it doesn't.

That's probably true, but a tumbling bullet isn't as aerodynamically
clean as one falling base or point first. So if stability isn't maintained,
terminal velocity will be even lower.

Gary

On Wed, 17 Dec 2003 14:41:01 GMT, "Bob Swinney" wrote:
Don sez:

"Acceleration is, by definitition, rate of change of velocity with
time AKA dv/dt. If me arse is changing velocity at the moment I
sure don't notice it."

That's because you aren't (we aren't) finely tuned enough to notice the
teensy-tiny interval dv/dt. grin

But we are finely tuned enough to notice the results of non-zero
accelerations. The integral of vt dv/dt is distance traveled in a given
amount of time. When that distance is zero, as it is when we're
sitting on a chair, then dv/dt must also be zero. In other words,
in a static system, acceleration must be zero.

Gary

On Mon, 15 Dec 2003 09:03:45 +0800, "Dean"
wrote something
.......and in reply I say!:

A lead ball say around 1-1.5" diameter will stop at around 190-200
mph. I would not think a bullet would fall "bullet shaped", and would
not get much faster, if as fast. I would imagine larger objects would
have less air problems (more mass per surface area) and get a bit
faster even if not as dense in materials. Shape also matters. A humman
will fall a lot faster if arrowing down than if spreadeagled.

I have watched a fascinating thing about a guy who worked with
falcons. He had one that could fall at over 220mph, due to its shape
(teardrop) and they had not finished testing. So a feather _can_ drop
faster than a brick! G

I also saw a thing about cats. They apparentoy have quite a high
surival rate from apartment falls. Up to about 2 storeys they have no
trouble. From there until 7 storeys they get increasingly hurt and
killed. After that, they reach terminal velocity (funny I thought
_terminal_ velocity was about 0, but anyway) and have time to realise
that they are not going to go any faster. They relax, and spread out,
and may even slow down. They get broken legs and cracked ribs and
that's that.

Anumals were injured during the making of this production. The show
claimed that this was based on vet practice records, not actual
experiments.

This is sort of metalwork - it involves lead. I was watching the Iraqies
celebrating the capture of Saddam by firing their rifles and guns into the
air. How dangerous are the bullets coming down ? I know they fall back much
slower than they leave the gun barrel, but they must still be doing a fair
clip. They said 4 people so far have been killed by this but I guess in Iraq
its hard to know which bullets came from where. As a few of you know about
guns I thought I'd ask here.


************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

On Wed, 17 Dec 2003 04:39:59 GMT, "Bob Swinney"
wrote something
.......and in reply I say!:

Ignoring this will just confuse you.

Maybe, Ted, but *acceleration* from gravity is not diminished in any way.

But we are not talking about acceleration from gravity. We are talking
about acceleration of an object (a bullet falling in air).
************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

On Wed, 17 Dec 2003 14:41:01 GMT, "Bob Swinney"
wrote something
.......and in reply I say!:

Don sez:

"Acceleration is, by definitition, rate of change of velocity with
time AKA dv/dt. If me arse is changing velocity at the moment I
sure don't notice it."

Ahah! But it is! The earth travels in a circular orbit. In physics,
velocity is understood to have direction. IIRC, your arse has not
changed speed but is constantly changing velocity. You are right. You
do not notice it. G
************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

On Tue, 16 Dec 2003 15:13:16 -0800, "lane"
lane_nospam@copperaccents_dot_com wrote something
.......and in reply I say!:


It supposedly says: "As a point of interest a velocity of about between 160
and 200 f/s (±) is needed to penetrate skin."

In my young, teenage, girl hunting days I would been worried by that
statement.......
************************************************** ** sorry
remove ns from my header address to reply via email

I was frightened by the idea of a conspiracy that was
causing it all.
But then I was terrified that maybe there was no plan,
really. Is this unpleasant mess all a mistake?

Gary Coffman wrote:

accelerations. The integral of vt dv/dt is distance traveled in a given

Are you trying to say Integral of v(t)dt?

Ted

Gary Coffman wrote:

(normal bullet
path is a parabola).

Not in air.

Ted