34 replies to this topic

[Bart]

if there is no friction, and there is gravity, the ball will be oscillation forever

sorry, but that's the way it is

[olli]

that could be a THEORY. dont say thats the way it is, because unless we try it then we wont know. that could happen it might not. but what i described was with friction and is my theory of what would happen. so far we have 2 theorys. mine and yours

[olli]

well ive been asking the physics teachers at my school to get some clarification. (with like a billion science degrees, so they know what thier talking about )

some agree with me some agree with 2playgames.

well what i described in my first post would be a dampened harmonic vibration, if there was friction present.

2playgames says that the ball would ossalate between the to points for ever and keep the same distance away from each hole, if there was no friction. that is a simple harmonic motion.

these are the two theorys. some suggested more, but i cant remeber them

only way to find out is the test it

Edited by olli, 21 March 2007 - 08:34 AM.

[Bart]

well what i described in my first post would be a dampened harmonic vibration, if there was friction present.

of course, but then you were theorising that the vibration would be dampened, even if there was no friction, which is incorrect

[AdmiralGT]

If there is no air resistance ie in a vacuum, the ball will experience Simple Harmonic Motion (it will osciallate between point A and B)
If there is air resistance, the ball will experience Damped Harmonic Motion (it will osciallate, however, each time the point where it changes direction will get closer and closer to the centre of the Earth until it eventually comes to rest at the centre).

Oh, and if you like, you can argue with my 4 year physics degree, but, I assume you will not.

[olli]

yes yes yes yes!!!! IS What i was describing. and 2playgames... i edited my first post and added that in. i spelt the wrong theory. i assumed that there would be friction present. which is what i described in my first post(dampened harmonic vibrations), but named it the wrong thing. i apologise. what you were describing was correct also if there was no friction.

and i will argue with you AdmeralGT, with my 6 years of studying physics at school joke

so now we know the theorys

Edited by olli, 21 March 2007 - 05:50 PM.

[CodeCat]

Sorry to um... drop the ball on you. But even without aerodynamic friction, yes even in a vacuum, the ball still loses energy. The reason is similar to what happens when an electric charge is moved around: it radiates some of its energy in the form of electromagnetic waves. So what if you move mass around? Exactly, gravity waves. This energy loss is absolutely tiny, but nonetheless it does exist. It causes the earth's rotation to slow down each day. So, eventually, after billions of years maybe, the ball will come to a complete stop relative to earth. That is, assuming the sun doesn't blow it up first.

[Calamity_Jones]

Exactly, there is absolutely not, never, ever, anywhere and kind of a perfect system. Things will always lose energy as stability favours things that have less energy. Things with a lot of free energy don't last long, they want to lose it. You can see it everywhere... chemical reactions are the most obvious example. The most reactive elements are the ones with spare electrons in their outer energy levels. The noble gases have full shells and don't react with shit.

[duke_Qa]

But even without aerodynamic friction, yes even in a vacuum, the ball still loses energy. The reason is similar to what happens when an electric charge is moved around: it radiates some of its energy in the form of electromagnetic waves. So what if you move mass around? Exactly, gravity waves. This energy loss is absolutely tiny, but nonetheless it does exist. It causes the earth's rotation to slow down each day. So, eventually, after billions of years maybe, the ball will come to a complete stop relative to earth. That is, assuming the sun doesn't blow it up first

nah, i would say that the motion of the sun and the motion of earth is connected the same way that magnetic fields around a live wire goes in clockwise or counter-clockwise direction of the cable depending on the direction of the current. as long as the sun is affected by cosmic energies its gravity will most likely keep us spinning around. but indirectly they both will probably stop the day the sun stops moving. but then again by that time the sun has imploded and taken care of earth anyway.





edit: damn you cal

Edited by duke_Qa, 26 March 2007 - 11:40 PM.

[Bart]

Sorry to um... drop the ball on you. But even without aerodynamic friction, yes even in a vacuum, the ball still loses energy.

and where would this energy go, hmm?

[CodeCat]

Out into space. And it would move other bodies that have mass around a tiny bit.

Honestly, it's nothing weird. Just imagine I have a positive electric charge in a tube. It can move freely around the tube, but can't go out of it. Now, I take a negative charge in my hand, and move it up and down along the outside of the tube. The laws of electromagnetism say that the positive charge will be attracted by the negative one, and will move up and down with it.

Now, imagine that negative charge again, but this time moving up and down extremely fast: a million times a second or even more. Again, it's obvious that anything near it will start moving up and down just as fast (albeit not as much). However, as you may know, an oscillating electric field (as is the case here) is manifested as electromagnetic waves. And we all know those carry energy, and in this case in the form of radio waves. But this must mean that this oscillating charge slowly loses energy just by radiating energy away from it in the form of waves. So even if there is no friction, the fact that it's moving up and down leads to energy loss by itself, and therefore causes it to slow down and asymptotically come to a stop.

The exact same thing happens to the ball, except that the energy it radiates is not electromagnetic, but gravitational.

[olli]

ok now you have swayed be back to what i was origionally describing, but people kept saying i was wrong! i think we need admiral GTs physics degree here....

[AdmiralGT]

Sorry to um... drop the ball on you. But even without aerodynamic friction, yes even in a vacuum, the ball still loses energy. The reason is similar to what happens when an electric charge is moved around: it radiates some of its energy in the form of electromagnetic waves. So what if you move mass around? Exactly, gravity waves. This energy loss is absolutely tiny, but nonetheless it does exist. It causes the earth's rotation to slow down each day. So, eventually, after billions of years maybe, the ball will come to a complete stop relative to earth. That is, assuming the sun doesn't blow it up first.

Out into space. And it would move other bodies that have mass around a tiny bit.

Honestly, it's nothing weird. Just imagine I have a positive electric charge in a tube. It can move freely around the tube, but can't go out of it. Now, I take a negative charge in my hand, and move it up and down along the outside of the tube. The laws of electromagnetism say that the positive charge will be attracted by the negative one, and will move up and down with it.

Now, imagine that negative charge again, but this time moving up and down extremely fast: a million times a second or even more. Again, it's obvious that anything near it will start moving up and down just as fast (albeit not as much). However, as you may know, an oscillating electric field (as is the case here) is manifested as electromagnetic waves. And we all know those carry energy, and in this case in the form of radio waves. But this must mean that this oscillating charge slowly loses energy just by radiating energy away from it in the form of waves. So even if there is no friction, the fact that it's moving up and down leads to energy loss by itself, and therefore causes it to slow down and asymptotically come to a stop.

The exact same thing happens to the ball, except that the energy it radiates is not electromagnetic, but gravitational.

Analogies are fantastic, however, in this case, their use is misguided. While electromagnetic waves do propagate from oscillation electrical charges, the same cannot be said for an oscillating mass. The electromagnetic (essentially part of the electroweak) force behaves very differently to the gravitational force. The theory of graviational waves or gravitons is only hypothetical and is only described by String Theory and has a lot of trouble at high energies in the Standard Model.

And this "gravity wave" is not the reason why the rotation of the Earth slows. The rotation of the Earth slows while the rotation of the Moon increases. This is caused by Tidal Acceleration, whereby tides caused by the Moon are "dragged" forward by the rotation of the Earth. This causes Torque to occur, accelerating the Moon and decelerating the Earth. This effect would eventually lead to a "month" and a "day" being the same length, meaning the Moon would be in a Geostationary orbit.

[Bart]

This effect would eventually lead to a "month" and a "day" being the same length, meaning the Moon would be in a Geostationary orbit.

and erm...how long will that take?

by the way, did you guys know the magnetic north and south pole are going to switch around? i believe it will happen soon...


...erm, no not soon but it's already affecting satellites
http://www.impactlab...=...le&sid=3672

anyway, i have a theory: could it be possible that the fact that the magnetic poles are close to the geographic poles, be a sheer coincidence? that they were somewhere on the equator a long time ago, but not when humans invented compasses and stuff?

[AdmiralGT]

This effect would eventually lead to a "month" and a "day" being the same length, meaning the Moon would be in a Geostationary orbit.

and erm...how long will that take?

by the way, did you guys know the magnetic north and south pole are going to switch around? i believe it will happen soon...


...erm, no not soon but it's already affecting satellites
http://www.impactlab...=...le&sid=3672

anyway, i have a theory: could it be possible that the fact that the magnetic poles are close to the geographic poles, be a sheer coincidence? that they were somewhere on the equator a long time ago, but not when humans invented compasses and stuff?

Billions of years, at which point the Sun would have gone Nova and probably destroyed the Earth/significantly changed it's orbit.

As for the magnetic poles, they settle near the geographical poles due to the rotation of the Earth, since the liquid core of the earth is thought to cause our magnetic field, the rotation of the Earth is the main cause of the poles. However, other effects cause the poles to shift in time, which takes hundreds of years. And yes, we are due a shift in the poles, sometime in the next few millenia.