Author Topic: why are you an atheist?  (Read 55828 times)

Re: why are you an atheist?
« Reply #465 on: August 08, 2019, 03:00:00 PM »
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My gymnasium final project was in that in physics. I got what amounts to a C in grades :/ because I effed up the gravitational slingshot equations for it. We didn't have google back then.

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I see that you are prime candidate to buy my next book - Physics from Classical to Quantum, a self-teaching guide. Should be in store by Jan. 2020.Can I count on you?

Offline Sal1981

Re: why are you an atheist?
« Reply #466 on: August 08, 2019, 03:11:38 PM »
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I see that you are prime candidate to buy my next book - Physics from Classical to Quantum, a self-teaching guide. Should be in store by Jan. 2020.Can I count on you?
Wouldn't hurt. I'd like a physical copy though.

Last book that even came remotely close to a physics book was Hawkings' A Brief History of Time. Not exactly heavy on the physics part, as it was directed more towards layman understanding of physics.
"The first principle is that you must not fool yourself - and you are the easiest person to fool" --- Richard P. Feynman

Re: why are you an atheist?
« Reply #467 on: August 08, 2019, 03:24:13 PM »
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Wouldn't hurt. I'd like a physical copy though.

Last book that even came remotely close to a physics book was Hawkings' A Brief History of Time. Not exactly heavy on the physics part, as it was directed more towards layman understanding of physics.

There is going to be an appendix that will cover the math: calculus, linear algebra, group theory, and assorted special functions. But make no mistake, math is the language of physics. In my book, contrary to other textbooks, I take the reader through every step of a derivation. So that you don't get bogged down by the math. But you still have to go through, otherwise your understanding remains below par.

Offline Cavebear

Re: why are you an atheist?
« Reply #468 on: August 08, 2019, 03:29:37 PM »
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Slight correction: rotation direction of the planet, not gravity... Civ2, that still exists??

Sorry, I think of planets as gravity wells.

Civ2 exists if you can find a Windows 95/98 computer.  I bought one online and it stays offline for safety.  I might also buy a Commodore 64 because there were some really crappy quest games I would love to play again.
Atheist born, atheist bred.  And when I die, atheist dead!

Re: why are you an atheist?
« Reply #469 on: August 08, 2019, 03:59:21 PM »
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Sorry, I think of planets as gravity wells.


That's fine as long as you don't mix up gravitational energy with rotational energy - not the same.

Quote
Civ2 exists if you can find a Windows 95/98 computer.  I bought one online and it stays offline for safety.  I might also buy a Commodore 64 because there were some really crappy quest games I would love to play again.


I'm no longer into video games, though I was when the first pc's came out in the 80's- it was the only software available.

Offline Cavebear

Re: why are you an atheist?
« Reply #470 on: August 08, 2019, 04:04:04 PM »
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That's fine as long as you don't mix up gravitational energy with rotational energy - not the same.


I'm no longer into video games, though I was when the first pc's came out in the 80's- it was the only software available.

I'm still pecking at my brain about rotational energy.  It wouldn't work with a perfectly spherical planet of completely uniform density, would it?  Ignore centrifugal force on the planet.

Did you play any Commodore 64 games?
Atheist born, atheist bred.  And when I die, atheist dead!

Re: why are you an atheist?
« Reply #471 on: August 08, 2019, 05:00:36 PM »
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I'm still pecking at my brain about rotational energy.  It wouldn't work with a perfectly spherical planet of completely uniform density, would it?  Ignore centrifugal force on the planet.

Nothing to do with "perfectly spherical planet of completely uniform density".


Let me first take a simple scenario with no gravity involved. You are at rest (KE =0) in front of a merry go round.  You step on it, holding to a handle or something. You now have rotational energy - the merry go round will slow down, however if there is an electrical input, that will compensate and keep the merry go round at constant angular speed. You and the merry go round are one body. Now you let go of the handle. You will fly out at a tangent with some velocity (KE ≠0). You just gained rotational energy. Of course, the merry go round would slow down, except for the electrical input. Now let's transfer that into outer space. The equivalent scenario is you orbiting around the earth with a velocity such that you are at rest with a fixed point on the surface of the earth, your house - GPS are satellites that do just that. You and the earth are one body. Now to let go, it's a bit more complicated than just letting go of the handle. You would need thrusters to escape the pull of gravity. Suppose you provide just enough energy to do that. Then as in the case of the merry go round, you will be propelled into space with rotational energy. Now think of the flyby object as it goes into orbit. At one point it's right over your house, the fixed point, and it has just enough energy to escape like you did. It will do exactly the same, it will be propelled with additional rotational energy.


Hope this clear, if not, let me know what isn't clear.




Offline Cavebear

Re: why are you an atheist?
« Reply #472 on: August 08, 2019, 05:39:33 PM »
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Nothing to do with "perfectly spherical planet of completely uniform density".


Let me first take a simple scenario with no gravity involved. You are at rest (KE =0) in front of a merry go round.  You step on it, holding to a handle or something. You now have rotational energy - the merry go round will slow down, however if there is an electrical input, that will compensate and keep the merry go round at constant angular speed. You and the merry go round are one body. Now you let go of the handle. You will fly out at a tangent with some velocity (KE ≠0). You just gained rotational energy. Of course, the merry go round would slow down, except for the electrical input. Now let's transfer that into outer space. The equivalent scenario is you orbiting around the earth with a velocity such that you are at rest with a fixed point on the surface of the earth, your house - GPS are satellites that do just that. You and the earth are one body. Now to let go, it's a bit more complicated than just letting go of the handle. You would need thrusters to escape the pull of gravity. Suppose you provide just enough energy to do that. Then as in the case of the merry go round, you will be propelled into space with rotational energy. Now think of the flyby object as it goes into orbit. At one point it's right over your house, the fixed point, and it has just enough energy to escape like you did. It will do exactly the same, it will be propelled with additional rotational energy.


Hope this clear, if not, let me know what isn't clear.

Well, now is isn't, even more.  I thought you were referring to a sort of density bulge that would apply a greater gravitational pull on any approaching body moving at a slower speed than the planetary rotation.  Part of my confusion is that we are talking about a non-thrusting object that is not in orbit around a planetary mass, just passing by. 

I don't see how the rotating planet matters if it is not uniform.  The passing object doesn't know or care about the volume or rotation of the mass below UNLESS it it is not uniform.  Gravity is the only thing that will affect the passing object.  If the planetary body is uniform is shape  and density, the passing object react to it as a singularity.

If the planetary object is NOT uniform, the passing object will react to the differences in mass as the body rotates and that will affect speed as the moon is affected by the rotation of the non-uniform Earth.

So I still don't have an answer to my question.
Atheist born, atheist bred.  And when I die, atheist dead!

Re: why are you an atheist?
« Reply #473 on: August 08, 2019, 06:47:39 PM »
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I see that you are prime candidate to buy my next book - Physics from Classical to Quantum, a self-teaching guide. Should be in store by Jan. 2020.Can I count on you?
You can count on me.  Just give me more 'heads up' as the time nears.
Is God willing to prevent evil, but not able?
Then he is not omnipotent,
Is he able but not willing?
Then whence cometh evil?
Is he neither able or willing?
Then why call him god?

Re: why are you an atheist?
« Reply #474 on: August 08, 2019, 06:48:40 PM »
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Well, now is isn't, even more.  I thought you were referring to a sort of density bulge that would apply a greater gravitational pull on any approaching body moving at a slower speed than the planetary rotation.  Part of my confusion is that we are talking about a non-thrusting object that is not in orbit around a planetary mass, just passing by. 

I don't see how the rotating planet matters if it is not uniform.  The passing object doesn't know or care about the volume or rotation of the mass below UNLESS it it is not uniform.  Gravity is the only thing that will affect the passing object.  If the planetary body is uniform is shape  and density, the passing object react to it as a singularity.

If the planetary object is NOT uniform, the passing object will react to the differences in mass as the body rotates and that will affect speed as the moon is affected by the rotation of the non-uniform Earth.

So I still don't have an answer to my question.

This is standard physics. In my textbook it would be done with equations, but would be the same explanation. I'm not only an author of physics book, but I also taught physics for 29 years, at college level. The only way to help you out is if you ask direct questions on the two scenarios I gave you. Meaning: clear your head of any preconceived ideas. Read it again line by line, and if anything is unclear, ask the appropriate question. That's what I've always told my students. The whole thing is about transfer of energy, particularly rotational energy, whether it's an ordinary object or the moon, the principle is the same. Gravity alone does not explain the slingshot effect. By the conservation of energy, the body would have the same energy when it leaves as when it entered into orbit, hence the same speed. So where does that extra energy come from? From the rotating planet. There is no other explanation.

Offline Baruch

Re: why are you an atheist?
« Reply #475 on: August 08, 2019, 10:52:05 PM »
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So you are saying a flyby has to be in the direction of planetary rotation?

Why are launches on the ground, in the same direction as the Earth's rotation?  You have to add less energy to get to orbit.  With the exception of satellites taking a polar orbit, where coverage is more important (spy satellites).
Zampa xiquihto.  Amo nimitzcuamachilia.
Say it again.  I don't understand you.

Offline Cavebear

Re: why are you an atheist?
« Reply #476 on: August 12, 2019, 06:48:46 AM »
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This is standard physics. In my textbook it would be done with equations, but would be the same explanation. I'm not only an author of physics book, but I also taught physics for 29 years, at college level. The only way to help you out is if you ask direct questions on the two scenarios I gave you. Meaning: clear your head of any preconceived ideas. Read it again line by line, and if anything is unclear, ask the appropriate question. That's what I've always told my students. The whole thing is about transfer of energy, particularly rotational energy, whether it's an ordinary object or the moon, the principle is the same. Gravity alone does not explain the slingshot effect. By the conservation of energy, the body would have the same energy when it leaves as when it entered into orbit, hence the same speed. So where does that extra energy come from? From the rotating planet. There is no other explanation.

Thank you and I finally catch the error I sensed in your posts.  You were talking about the rotational energy of the planet and I couldn't understand how that mattered unless the planet was non-uniform.  It is the ORBITAL motion of the planet that gives the increased velocity to the object not the rotation.

THAT makes sense.
Atheist born, atheist bred.  And when I die, atheist dead!

Re: why are you an atheist?
« Reply #477 on: August 12, 2019, 09:09:22 AM »
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Thank you and I finally catch the error I sensed in your posts.  You were talking about the rotational energy of the planet and I couldn't understand how that mattered unless the planet was non-uniform.  It is the ORBITAL motion of the planet that gives the increased velocity to the object not the rotation.

THAT makes sense.

Equal and opposite reactions... Just think how much our space probes have altered the orbits of the planets already.  ;)
Gentlemen, you can't fight in here! This is the War Room! -- President Merkin Muffley

My mom was a religious fundamentalist. Plus, she didn't have a mouth. It's an unusual combination. -- Bender Bending Rodriguez

Re: why are you an atheist?
« Reply #478 on: August 12, 2019, 06:55:39 PM »
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It is the ORBITAL motion of the planet that gives the increased velocity to the object not the rotation.

THAT makes sense.

👍
Gentlemen, you can't fight in here! This is the War Room! -- President Merkin Muffley

My mom was a religious fundamentalist. Plus, she didn't have a mouth. It's an unusual combination. -- Bender Bending Rodriguez

Offline Cavebear

Re: why are you an atheist?
« Reply #479 on: August 12, 2019, 10:33:18 PM »
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Equal and opposite reactions... Just think how much our space probes have altered the orbits of the planets already.  ;)

I've wondered about that.  Not that a small flyby makes much difference, but after enough flybys...

If we can (sometime in the future) move Earth away from the Sun to escape overheating by graviational attraction of asteroids or something, flybys could have an affect.
Atheist born, atheist bred.  And when I die, atheist dead!

 

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