I think the look on BO's face is,

WHAT THE HELL DID I GET MYSELF INTO.IF I NEW THEN WHAT I KNOW NOW I'D NEVER HAVE RUN.

DON

WHAT THE HELL DID I GET MYSELF INTO.IF I NEW THEN WHAT I KNOW NOW I'D NEVER HAVE RUN.

DON

- BIG BEAM
**Stove/Furnace Make:**USS Hot blast**Stove/Furnace Model:**1557M

BIG BEAM wrote:I think the look on BO's face is,

WHAT THE HELL DID I GET MYSELF INTO.IF I NEW THEN WHAT I KNOW NOW I'D NEVER HAVE RUN.

Because of secrets he was briefed on by the CIA?

- Devil505
**Stove/Furnace Make:**Harman**Stove/Furnace Model:**TLC-2000

Devil505 wrote:mikeandgerry wrote:The moon's gravitational pull is so weak that only a "gunshot" like blast was needed to propel the LM into orbit.

It's not THAT weak Mike. To be exact, it's 1/7th that of Earth's. Less, to be sure, but still pretty significant to escape.

Gravity is a an accelerative force, meaning that for every unit of distance further away the two bodies are, the attractive force gets weaker by the square of the distance. It takes far less energy to move away from the moon compared to the earth than 1/7th due to this effect. Also, In an atmosphere that is void, there is even less of an energy requirement to move away.

Examine the Wikipedia video. There is a sharp blast which kicks up some debris and dust that is deflected by the platform (the lower half of the LM) but no need for sustained rocket thrust.

- mikeandgerry
**Stoker Coal Boiler:**Axeman-Anderson Anthratube 130-M

mikeandgerry wrote:Gravity is a an accelerative force, meaning that for every unit of distance further away the two bodies are, the attractive force gets weaker by the square of the distance.

A bit off topic here Mike but if you're a mathematician (I'm not) here you go:

II. RELEVANT CLASSICAL MECHANICS

Let x, v, and a denote distance, velocity, and acceleration respectively of an object along a line. Then, from the chain rule we have:

(1) a = dv/dt = (dv/dx)*(dx/dt) = v*(dv/dx)

and hence

(2) a*dx = v*dv

For convenience let f(x) be the indefinite integral of a*dx.

Consider an object moving position x1 to position x2 with initial velocity v1 and final velocity v2. We integrate both sides of (2) to get

(3) v2**2 - v1**2 = 2 * (f(x2)-f(x1))

Now consider the case where the acceleration of the the object is due to gravitational forces from one or more masses M_i located at positions X_i. The acceleration due to mass M_i is given by

(4) a_i(x) = G*M_i/(x-X_i)**2

Full formulas here:

http://home.tiac.net/~cri/1999/moon.html

This link is broken, either the page no longer exists or there is some other issue like a typo.

- Devil505
**Stove/Furnace Make:**Harman**Stove/Furnace Model:**TLC-2000

Just how much free time to you guys have? This discussion has no ending point. You can take a man to water, but you can't make him drink! You can hold his head under water, but you can't make him open his mouth. You can argue day and night and what the hell does it prove? That you were/are married, and you haven't learned anything yet? She is ALWAYS right, dummie. They must call you 'devil ' for a reason. The political season is OVER, your side won.....let it die. I thought this was a coal forum, not a "I hit you last" kiddie game. Yup, I'll exercise my rights and stay the hell off this topic. Thanks for nothing.

- whistlenut
**Stoker Coal Boiler:**AA130's,260's, AHS130&260's,EFM900,GJ&VanWert**Hand Fed Coal Boiler:**Franks Boiler,Itasca415,NYer130,Van Wert**Hot Air Coal Stoker Furnace:**Yellow Flame**Hot Air Coal Stoker Stove:**Alaska-4,Keystoker-2,**Hand Fed Coal Stove:**Alaska,Gibraltor,Keystone,Vc Vigilant 2**Hand Fed Coal Furnace:**Van Wert, NYer's, Ford,Jensen.**Coal Size/Type:**Rice,Buck,Pea,Nut&Stove**Other Heating:**Oil HWBB

Whistlenut,

I learned to bypass the threads I'm not interested in. It helps to keep my blood pressure under control.

I learned to bypass the threads I'm not interested in. It helps to keep my blood pressure under control.

- billw
**Stove/Furnace Make:**EFM 520**Stove/Furnace Model:**GOODBYE OIL COMPANY

Devil505 wrote:BIG BEAM wrote:I think the look on BO's face is,

WHAT THE HELL DID I GET MYSELF INTO.IF I NEW THEN WHAT I KNOW NOW I'D NEVER HAVE RUN.

Because of secrets he was briefed on by the CIA?

That and he's probably privy to some info from certain select committees that he didn't have access to before.

DON

- BIG BEAM
**Stove/Furnace Make:**USS Hot blast**Stove/Furnace Model:**1557M

Not a mathematician devil? Who knew?

The math you provided is fine if you want to complicate the explanation with calculus. In the hypothetical situation presented, which was launching interstellar probes from Earth-Moon system or the Moon and the related cost benefit analysis(you must be a sci-fi fan), they sought to calculate velocities but stopped short of forces. I investigated your link. You stopped short of the part that confirmed what I stated.

What we are talking about is a problem of force, derived from F=ma. While the math you provided was fine for calculating the required velocities for those situations, it only touched on the problem of calculating the energy required for a mass to leave masses of two considerably different sizes and having considerably different atmospheres. The initial force may differ by the factor of 7 as you suggested but the sustained force and resulting energy required to escape the gravitational pull is far less than a factor of 7

From the link you posted:

(8) G*M_i = g_i*R_i**2

where R_i is a reference distance which, in subsequent calculations, is the mass body radius and g_i is the surface acceleration of gravity.

From equation (8) and these values we get

G*M_Earth = 398653. km**3/sec**2

G*M_Moon = 4893. km**3/sec**2

This will put it into layman's terms for you, from Wikipedia:

Earth's gravity

Every planetary body (including the Earth) is surrounded by its own gravitational field, which exerts an attractive force on all objects. Assuming a spherically symmetrical planet (a reasonable approximation), the strength of this field at any given point is proportional to the planetary body's mass and inversely proportional to the square of the distance from the center of the body.

The strength of the gravitational field is numerically equal to the acceleration of objects under its influence, and its value at the Earth's surface, denoted g, is approximately expressed below as the standard average.

g = 9.8 m/s2 = 32.2 ft/s2

This means that, ignoring air resistance, an object falling freely near the earth's surface increases its velocity with 9.8 m/s (32.2 ft/s or 22 mph) for each second of its descent. Thus, an object starting from rest will attain a velocity of 9.8 m/s (32.2 ft/s) after one second, 19.6 m/s (64.4 ft/s) after two seconds, and so on, adding 9.8 m/s (32.2 ft/s) to each resulting velocity.

Emphasis mine.

Your cut and paste touches on it in derivation 3 and 4.

The math you provided is fine if you want to complicate the explanation with calculus. In the hypothetical situation presented, which was launching interstellar probes from Earth-Moon system or the Moon and the related cost benefit analysis(you must be a sci-fi fan), they sought to calculate velocities but stopped short of forces. I investigated your link. You stopped short of the part that confirmed what I stated.

What we are talking about is a problem of force, derived from F=ma. While the math you provided was fine for calculating the required velocities for those situations, it only touched on the problem of calculating the energy required for a mass to leave masses of two considerably different sizes and having considerably different atmospheres. The initial force may differ by the factor of 7 as you suggested but the sustained force and resulting energy required to escape the gravitational pull is far less than a factor of 7

From the link you posted:

(8) G*M_i = g_i*R_i**2

where R_i is a reference distance which, in subsequent calculations, is the mass body radius and g_i is the surface acceleration of gravity.

From equation (8) and these values we get

G*M_Earth = 398653. km**3/sec**2

G*M_Moon = 4893. km**3/sec**2

This will put it into layman's terms for you, from Wikipedia:

Earth's gravity

Every planetary body (including the Earth) is surrounded by its own gravitational field, which exerts an attractive force on all objects. Assuming a spherically symmetrical planet (a reasonable approximation), the strength of this field at any given point is proportional to the planetary body's mass and inversely proportional to the square of the distance from the center of the body.

The strength of the gravitational field is numerically equal to the acceleration of objects under its influence, and its value at the Earth's surface, denoted g, is approximately expressed below as the standard average.

g = 9.8 m/s2 = 32.2 ft/s2

This means that, ignoring air resistance, an object falling freely near the earth's surface increases its velocity with 9.8 m/s (32.2 ft/s or 22 mph) for each second of its descent. Thus, an object starting from rest will attain a velocity of 9.8 m/s (32.2 ft/s) after one second, 19.6 m/s (64.4 ft/s) after two seconds, and so on, adding 9.8 m/s (32.2 ft/s) to each resulting velocity.

Emphasis mine.

Your cut and paste touches on it in derivation 3 and 4.

- mikeandgerry
**Stoker Coal Boiler:**Axeman-Anderson Anthratube 130-M

mikeandgerry wrote:Not a mathematician devil? Who knew?

I posted that as a joke Mike.

whistlenut wrote:They must call you 'devil ' for a reason. The political season is OVER, your side won.....let it die. I thought this was a coal forum, not a "I hit you last" kiddie game. Yup, I'll exercise my rights and stay the hell off this topic. Thanks for nothing.

The election is over & coal is the purpose of this forum....but....Many of us have other interests & just enjoy a friendly debate on various subjects in this....the General OFF-Topic Forum. My advice is to read only the threads that interest you. What's the problem with that?

- Devil505
**Stove/Furnace Make:**Harman**Stove/Furnace Model:**TLC-2000

And I got it! Which is why I jibed you back.

I am not a mathematician either but I did study some calculus and physics.

I know just enough to get my self in trouble at times.

I am not a mathematician either but I did study some calculus and physics.

I know just enough to get my self in trouble at times.

- mikeandgerry
**Stoker Coal Boiler:**Axeman-Anderson Anthratube 130-M

Complicate the explanation with calculus?......complicate??.....that's what makes it fun...it's just starting to get interested! ......and yes I AM a mathematician...calculus specifically!

- rocketjeremy
**Stoker Coal Boiler:**EFM DF-520**Coal Size/Type:**Rice**Stove/Furnace Make:**EFM**Stove/Furnace Model:**DF520

O.K. Devil,I am not certain that Oswald acted alone but from my reading , I will give you this. That Mannlicher Carcano rifle was test fired by a team from the F.B.I. ,a civilian group of known marksman, and the Army Ordnance group.The Army Ordance group fired 47 rounds with rifle serial # C2766 [THE rifle] and found it to be at least as accurate as the M1 and the government issue at the time ,the M14. It was capable of the time required to get off the shots if using open sights.It was said at the time that it was a cheap piece of"junk".It was manufactured at theTerni Arsenal in Italy in 1940 and likely used in the war until Italy surrendered, Sept.1943. The Army ordnance people classified the stock as marked,the action as smooth,and the bore as fair.The rifle was the subject of a possession lawsuit. The federal government prevailed and the rifle is now in the Federal Archives.These are all documented facts and not heresay or myth. I cannot understand what they are talking about when they say the design of the bolt action contributed to rapid firing. I thought a bolt action was a bolt action??? Since I have not drawn my own conclusion as of yet I will continue to research one of the most horrendous and sad tradgedys in American history.

- stovepipemike
**Stove/Furnace Make:**Keystoker**Stove/Furnace Model:**KAA-2

stovepipemike wrote:O.K. Devil,I am not certain that Oswald acted alone

B4 Richard locks this thread for going off topic Mike, I'm going to start a new thread specifically for conspiracy theories, since there seems to be much interest in them.

As far as this statement: ..."I cannot understand what they are talking about when they say the design of the bolt action contributed to rapid firing. I thought a bolt action was a bolt action???"

While I'm far from a firearms expert, (Dr. Atwater from "Tales Of The Gun" is! ) but not all bolt actions are the same. Some are easier to operate & thus faster than others. (I think the Lee Enfield rifle was known for a nice bolt action, but I may be mistaken)

- Devil505
**Stove/Furnace Make:**Harman**Stove/Furnace Model:**TLC-2000

Place would be pretty boring with just coal topics. I think the off coal posts add a little fun.

- ken
**Stove/Furnace Make:**Keystoker - Rice Coal**Stove/Furnace Model:**75K - Bay Window - Direct Vent

ken wrote:Place would be pretty boring with just coal topics. I think the off coal posts add a little fun.

Indeed. Not to mention that there simply aren't enough coal issues to keep us all checking back here as regularly as we do when current events are being discussed.

The simple truth is that, without regular traffic, boards wither and die. If you're a hockey fan, it's sort of like the Rodney Dangerfield quote: "I went to a fight the other night and a hockey game broke out."

- stockingfull
**Stove/Furnace Make:**Yellow Flame**Stove/Furnace Model:**W.A. 150 Stoker Furnace

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