Neutrinos back into the picture?

[chroot]

no - actaully the go faster when they are nearer to the sun (approaching perihelion - hope I said that right!). One of Kepler's laws.

While this is true, let's just assume circular orbits for the sake of this discussion. Beatrix & Co. seem to have some very grave misunderstandings of Newtonian gravitation, and we need to clear up the easy bits first.

- Warren

 

[Chronos]

so, basically, the planets are slowing down around the sun?? should the years be getting longer or something??

Actually, the orbital period decreases as they get nearer to the sun. A Kepler's second law thing.

 

[Math Is Hard]

we need to clear up the easy bits first.

OK, good point. I'll be quiet now.

 

[beatrix kiddo]

For the sake of planets, which are very, very massive, there is essentially no drag and they are essentially not slowing down.

ESSENTIALLY?? but there still is a slight drag! and it makes sense that the planets get faster the closer they get to the sun, because the sun pushes them out and increases their velocity...

 

[beatrix kiddo]

Beatrix & Co. seem to have some very grave misunderstandings of Newtonian gravitation, and we need to clear up the easy bits first.

not undermining my intelligence are we, chroot??

 

[chroot]

ESSENTIALLY?? but there still is a slight drag! and it makes sense that the planets get faster the closer they get to the sun, because the sun pushes them out and increases their velocity...

The slight drag is simply not relevant for something as massive as a planet.

Actually, the planet's speed grows larger as it approaches the Sun. This is contrary to what your push theory would suggest. When the planet is closest to the Sun, it would be intercepting more neutrinos, and would thus have a larger force applied to it. This would mean the planet's speed would be changing the most at the instant it is nearest the Sun (called perhelion). This is not what is observed. There is actually an extremum in the speed at perhelion -- the speed increases up to perhelion, then begins decreasing.

- Warren

 

[beatrix kiddo]

Well there is drag on just about everything to some degree or another. The planets feel very little drag but still feel it none the less. So yes, eventually they will fall into the sun (but not for a long long long time) unless some other body effects them and changes their orbit.

there seems to be some disunity amongst ur arguements...

 

[chroot]

not undermining my intelligence are we, chroot??

No. You are certainly ignorant, but you are not unintelligent.

- Warren

 

[chroot]

there seems to be some disunity amongst ur arguements...

What 'disunity?'

- Warren

 

[beatrix kiddo]

entropy told me the planets are slowing down and will eventually fall into the sun, but u say that they go faster when they approach the sun.

 

[beatrix kiddo]

i'm ignorant? I'm suprised that u think this... i thought u and i were becoming best friends or something!

 

[Entropy]

entropy told me the planets are slowing down and will eventually fall into the sun, but u say that they go faster when they approach the sun.

I never said they slowed down. Read my posts. I said they experence drag.

 

[beatrix kiddo]

This would mean the planet's speed would be changing the most at the instant it is nearest the Sun (called perhelion). This is not what is observed. There is actually an extremum in the speed at perhelion -- the speed increases up to perhelion, then begins decreasing.

not a single planet in this solar system has a perfect circular orbit around the sun. parts of the orbits go in, some swing out; so at some points it's closer than at others all the way around, right? this means that there would be a difference all the way around, not just at the closest and furthest points.. so actually, my theory goes along with current observations.

 

[beatrix kiddo]

ok.. my bad entropy.. the planets experience drag and will eventually fall into the sun..
drag- something that slows or delays progress.. dictionary.com

weird...

 

[chroot]

entropy told me the planets are slowing down and will eventually fall into the sun, but u say that they go faster when they approach the sun.

Your confusion is the reason I was trying to keep everyone from bringing up all sorts of secondary issues like non-circular orbits and drag due to the interplanetary medium.

It is true that the planets slow down due to drag, but not detectably so.

It's true that the planets do not orbit in perfectly circular orbits. They actually move along elliptical orbits, which bring them closer to the Sun during some portions of the orbit and further from the Sun during others. When a planet is closer to the Sun, it moves faster; when it is further, it moves slower. This is a result of the conservation of energy -- the loss of potential energy is concomittant with the increase in kinetic energy. It also commonly expressed as Kepler's second law of planetary motion, but Kepler's laws are really just observations of what things do in Newtonian gravitation.

To correct the recent abuse in notation, please recognize that it's impossible to assign a single speed to an object in an elliptical orbit, as it changes speed all the time. When a planet experiences drag, its total energy decreases, but its remaining energy is still conserved as per Kepler's laws.

- Warren

 

[chroot]

not a single planet in this solar system has a perfect circular orbit around the sun. parts of the orbits go in, some swing out; so at some points it's closer than at others all the way around, right? this means that there would be a difference all the way around, not just at the closest and furthest points.. so actually, my theory goes along with current observations.

No, your theory is contrary to those observations for reasons I have already explained in post you quoted. Your theory leads to a very different distance vs. speed relationship than does Newtonian gravitation.

- Warren

 

[Chronos]

The laws of planetary motion were first formulated by Kepler, who did so without benefit of a telescope or Newton's laws of gravity [Newton wasn't born yet]. See

http://csep10.phys.utk.edu/astr161/lect/history/kepler.html

Newton's laws corroborated Kepler's.

 

[JoeWade]

planets only experience drag if they're colliding with something... in space they're colliding with what?

there's no air

:uhh: :yuck: <-- face of guy with no air

 

[beatrix kiddo]

chroot u have a horrible misconception about my theory in that u think any sudden change in distance is going to result in instantaneous change in speed. the reason there is speed change is because the planet is absorbing neutrinos at a different rate.. (neutrino flux isn't the same everywhere in the solar system) however, just like the change in neutrino flux, the speed change will be gradual.. not instantaneous!

This is a result of the conservation of energy -- the loss of potential energy is concomittant with the increase in kinetic energy.

so as potential energy decreases... kinetic energy increases?? would this mean that energy does have something to do with gravity in the universe?

planets only experience drag if they're colliding with something... in space they're colliding with what?

there's no air

:uhh: :yuck: <-- face of guy with no air

that's ur first post?! what a waste...

 

[JoeWade]

would you rather my first post have been to call you a moron?

because i can go there if you want...

you seem to think that there's significant matter (air or particles or whatever) out there to cause SIGNIFICANT drag upon the planets, yet you have no basis for your assumptions. indeed scientific factual data backs up a position quite contrary to your notion.

so. where does your arrogance stem from?

 

[beatrix kiddo]

back

would you rather my first post have been to call you a moron?

oh yessss... i love it when people are assertive enough to call me an idiot, ****-head..

because i can go there if you want...

oh u went there...

you seem to think that there's significant matter (air or particles or whatever) out there to cause SIGNIFICANT drag upon the planets, yet you have no basis for your assumptions.

fine, joe. i was wrong about it being significant.. but there's still drag. my assumptions? i assumed that the planets would fall into the sun due to drag.. entropy says they will after a long ass time, but i thought it would be a lot sooner.. i was wrong-like... the basis for those assumptions is physics... drag slows crap down..

but i don't think I'm wrong about energy playing a role in gravity.

so. where does your arrogance stem from?

i'm too cool to know what that word means

 

[JoeWade]

but i don't think I'm wrong about energy playing a role in gravity

and what role do you think it plays, pray tell?

 

[beatrix kiddo]

i think that there is energy involved for the planets to maintain their orbit around the sun without sinking into space-time... (note: this is me ASSUMING for the current model)

 

[beatrix kiddo]

have u already heard about my push-theory, joe?

 

[JoeWade]

sure there's energy.

assume a planet travels a stable course across a space time curvature with one major entity (ie> sun) and you can see that it's orbit consists of a quantity of potential energy. both of it's position on the curvature (orbital ring) and of it's momentum/mass in it's orbit.

both of these potentials don't become kinetic unless there exists something else (ie> collision) for them to exert upon.

now were such particles to exist to cause significant drag upon planets, two things would be apparant. the speed would be slowing down, and the mass of the Earth would be increasing (accumulation of said particles)

but as was touched upon earlier, most of the particles in space also travel in an orbit similar to our own planets. so the particles wouldn't be colliding with us in that fashion. indeed if particles were simply sitting in space they'd be linearly pulled towards the sun-mass (non orbital collision course)

so you can put that crazy notion out of your head, Bea.

it doesn't work

 

[chroot]

chroot u have a horrible misconception about my theory in that u think any sudden change in distance is going to result in instantaneous change in speed. the reason there is speed change is because the planet is absorbing neutrinos at a different rate.. (neutrino flux isn't the same everywhere in the solar system) however, just like the change in neutrino flux, the speed change will be gradual.. not instantaneous!

I never said anything about instantaneous changes in speed. Here's what I said:

The Newtonian theory of gravitation says that as a planet approaches perihelion, the point of closest approach to the Sun, it speeds up. When it reaches perihelion, it is no longer gaining speed. At perihelion, the magnitude of the planet's acceleration is zero. After perihelion, it begins to slow down again.

Your theory says that as a planet approaches perihelion, the closest approach to the Sun, its neutrino bombardment gradually increases. Its neutrino bombardment is largest at perihelion. Since neutrino bombardment results in forces, and forces result in accelerations, the planet experiences its largest acceleration at perihelion.

Note the stark difference between the italicised text.

so as potential energy decreases... kinetic energy increases?? would this mean that energy does have something to do with gravity in the universe?

Every process in physics is related in some way to energy. I have no idea what precisely you're getting at, but yes, gravity and energy are related. If you pick a brick up over your head, you've used up chemical energy to give the brick potential energy. When you drop the brick, it trades that potential energy for kinetic energy, which it then uses to deform and injure your foot.

- Warren

 

[JoeWade]

foot-crush physics are the best for explaining physics to beginners.

my physics teacher did the bucket of water thing in class to demontrate the energy of inertia.

except one of the students was sleeping. so he got the gravity demonstration when she stopped spinning the bucket and up-ended it over his head.

 

[Math Is Hard]

except one of the students was sleeping. so he got the gravity demonstration when she stopped spinning the bucket and up-ended it over his head.

Way to make a point! :rofl:

 

[ArmoSkater87]

lol...chroot is on an ownage spree these past several days in this thread. But anyways, i have a few things i want cleared up. Just picture the Earth moon system. Say the moon increases in velocity around its orbit. Because of angular momentum shouldn't it go further out in its orbit. In other words shouldn't the orbit radius increase? And also...say the moon gets pushed out in its orbit, in this case the moon should decrease in speed shouldn't it?...since as it goes out, the gravitational force on the moon by the Earth decreases, and so less speed is needed to keep it in an equilibrium obrit. This is like a paradox to me, i don't know maybe I am just misunderstanding somehting.

 

[chroot]

Say the moon increases in velocity around its orbit. Because of angular momentum shouldn't it go further out in its orbit. In other words shouldn't the orbit radius increase?

The orbit will no longer be a circle -- it'll become an ellipse.

- Warren

 

[urtalkinstupid]

Assuming I understand the gist of this question, no, at least not in the classical sense of 'work' being performed.

You still haven't answered my question. By "work" are you referring to the amount of force applied to a distance.

$$W=\vex{F}dcos \theta$$

 

[beatrix kiddo]

Newton says:

At perihelion, the magnitude of the planet's acceleration is zero. After perihelion, it begins to slow down again.

i say:

the planet experiences its largest acceleration at perihelion.

kepler says:
http://www.walter-fendt.de/ph11e/keplerlaw2.htm

oh man... look at that orbit real close (not that close) and u'll see that mercury's velocity is fastest at the perihelion (or any other planet for that matter) agreeing with me...

I have no idea what precisely you're getting at, but yes, gravity and energy are related.

so we agree then.. gravity has something to do with energy.. maybe it's even dependent on some form of energy..

so you can put that crazy notion out of your head, Bea.

which notion? about the neutrinos or about the drag?

so he got the gravity demonstration when she stopped spinning the bucket and up-ended it over his head.

hmm.. reminds me of the time my teacher burnt my face with his cigarette end after he held me down and poured HCL acid in my ear...

 

[chroot]

You still haven't answered my question. By "work" are you referring to the amount of force applied to a distance.

$$W=\vex{F}dcos \theta$$

Yes, that's how work is defined.

In the case of picking a brick up off the ground, you do $W = mgh$ work on the brick. In its new position, it has gained that much potential energy. When you drop it, that potential energy is turned into kinetic energy. When it strikes the ground, that energy becomes heat and sound and broken molecular bonds.

- Warren

 

[Entropy]

oh man... look at that orbit real close (not that close) and u'll see that mercury's velocity is fastest at the perihelion (or any other planet for that matter) agreeing with me...

Velocity and acceleration are different.

 

[beatrix kiddo]

ahhh entropy but it accelerates to a faster velocity.. how's that??