That’s okay it was purely an explanation of my position and not a request or expectation of sympathy. But thanks anyway.In the speed of the thread, I missed your comment with regards to this. I hope everything works out OK for you.
I'm sorry for the loss also and apologize for not reading this comment closely.
Thanks for bringing this to our attention SOL.
Regards and Good Luck on getting back up to speed.
WindGrins.
-
Security incident: ISF was recently accessed by intruders. Please change your password, and change it anywhere else you used it. Read more
Merged DDWFTTW in a “Real” Wind
- Thread starter ynot
- Start date
- Status
I’m not even sure what you’re talking about here duffy. I know Humber posted a picture with that cow he has often used. It didn’t look photo-shopped to me, but as I was unable to find it just now I've asked Humber in a pm if that was in fact his cart.
If you have a link to that picture, please post it. Oh, and did you not notice the smiley’s next to my smelling the fear? I can’t really grok a propless cart advancing on the treadmill and certainly wouldn’t bet on it. Hmm, unless the odds were really tempting. I mean, we’re talking about a CoE violation here right? 100-1 maybe?
I have brought up my bet often-and I got 5-1 odds on it-both because I love the irony and to remind those who keep asserting I don't get it that if this is true perhaps Humber and Kammen are right?
Part of this post seems like it is responding to the wrong post. Not sure what you are talking about re any picture.
I am not sure what your smileys mean, I know your posts are always full of them but I always ignore them simply because, as I mentioned, I don't know what they all mean. Are you saying that you think Humber is as full of BS as the rest of us re his promised TM video?
If not, what I am asking is if you would like to wager on it. I will offer 100-1 providing you put up a minimum of $1000 USD.
recursive prophet
Graduate Poster
Good idea, ynot. You'd get much further explaining to Humber how the arm holding your cart on the treadmill plays no role in transferring the energy from the motor to the cart.
Here's a link to a short post you really should read. Take note, and proceed accordingly.
So you have 100k just sitting in your checking account, do you? Send me your bank statement, ss#, and mother's maiden name and we'll talk.
(if you put your cursor on the smiley's it will tell you what they mean. hth 
) And no, I don't thinks Humber is full of BS at all, but even He can be mistaken. (Though rarely )
Last edited:
Better still he should explain why and how it does as he claims.
Unfortunately yet another example of Spork being Spork. Also unfortunately many politicians that tell lies and make false accusations against their opponents get voted in to office.Here's a link to a short post you really should read. Take note, and proceed accordingly.
ThinAirDesigns
Graduate Poster
- Joined
- Nov 10, 2008
- Messages
- 1,058
Wow Ynot -- way to go to show that you brought a *really* bad case of the fleas with you. You can even turn Kudos into an insult. Way to go.
JB
But if you consider the forces on it, it will not roll around the cylinder at a fixed height even if placed in the cylinder at that height - right? After all, the weight acts at the ball's C.G. and the friction of the wall acts at the surface. So the ball will not stay on the line of latitude we want it to. What to do about that - if anything?
Yes, I insult those that insult me. You have trouble getting that straight - huh?
That is a flat out lie.
Another lie. You will clearly not stop with these lies.
Wow - it took about 2 posts before you came back to prove that last one a lie.
A) this makes me very happy
B) Define "inventions"
Ball in a cylinder
Assuming lossless interaction, vertical cylinder, real gravity, I would agree that it appears that to stay at one circular altitude, there needs to be a vertical component of force on the ball's surface to overcome gravity. (In the real world, it is obviously difficult to have this component with no loss but this is a thought experiment!)
There may be something I'm not considering here and the only thing that comes to mind are gyroscopic forces of the ball. Since I've seen a gyroscope do exactly what is described above. I do suppose it makes sense that a vertical force imposed on our lossless ball could potentially supply that.
I'm certainly not sure if this would work nor at what speed the ball would have to rotate for this to work. For me I would like to understand gyros better so if this is the case, I think this problem will enlighten me.
If a gyro force is the case, If one injects the ball with no vertical component of motion, and there is a vertical component of friction with the ball and wall (but no horizontal component) then I'm willing to be convinced this can work. If one could supply a small source of energy to the ball (say a magnetic stirrer) to overcome real world frictional loss in the horizontal plane, this may just work in practice.
My intuitive guess would be that the ball would oscillate between two minimally small deltas around the target altitude to make this work but that's just a guess with no analysis. My dynamics skills are such that I don't think I'm up to performing this calculation today but I'm capable of understanding a correct one.
It's a good well formed question. I'll be interested in the correct analysis and/or discussion when you or one of the posters are ready to supply!
Since this is a brainteaser, I'm willing to bet at some point that you're going to illustrate it can be done. If the description above is roughly correct (and I'm certainly not saying it is), then I would be interested in the speed that the ball would have to circulate given a radius R1 of the cylinder and R2 of the ball. (R2 may not be involved!). Since I know that for no motion the ball would fall, and at some speed there is a level where the ball is circulating fast enough to "hang on the wall", what is the cutoff speed for the phenomenon?
Regards,
WindGrins
Assuming lossless interaction, vertical cylinder, real gravity, I would agree that it appears that to stay at one circular altitude, there needs to be a vertical component of force on the ball's surface to overcome gravity. (In the real world, it is obviously difficult to have this component with no loss but this is a thought experiment!)
There may be something I'm not considering here and the only thing that comes to mind are gyroscopic forces of the ball. Since I've seen a gyroscope do exactly what is described above. I do suppose it makes sense that a vertical force imposed on our lossless ball could potentially supply that.
I'm certainly not sure if this would work nor at what speed the ball would have to rotate for this to work. For me I would like to understand gyros better so if this is the case, I think this problem will enlighten me.
If a gyro force is the case, If one injects the ball with no vertical component of motion, and there is a vertical component of friction with the ball and wall (but no horizontal component) then I'm willing to be convinced this can work. If one could supply a small source of energy to the ball (say a magnetic stirrer) to overcome real world frictional loss in the horizontal plane, this may just work in practice.
My intuitive guess would be that the ball would oscillate between two minimally small deltas around the target altitude to make this work but that's just a guess with no analysis. My dynamics skills are such that I don't think I'm up to performing this calculation today but I'm capable of understanding a correct one.
It's a good well formed question. I'll be interested in the correct analysis and/or discussion when you or one of the posters are ready to supply!
Since this is a brainteaser, I'm willing to bet at some point that you're going to illustrate it can be done. If the description above is roughly correct (and I'm certainly not saying it is), then I would be interested in the speed that the ball would have to circulate given a radius R1 of the cylinder and R2 of the ball. (R2 may not be involved!). Since I know that for no motion the ball would fall, and at some speed there is a level where the ball is circulating fast enough to "hang on the wall", what is the cutoff speed for the phenomenon?
Regards,
WindGrins
Last edited:
Mmmm....that wager won't happen ( and I think it's against the rules to make them), but you would lose if the videos exist or not, because for $100K, one could construct something either legitimate of false, that would take your money. In other words, the only limit for me in taking the money, is your capacity to see how it works. You already accept Spork's simple yarn, so you will certainly accept mine.
I have already done that Ynot. The arm may be free to turn on the pivot, but it can't rotate so is a torque reaction arm. It has mass, and can accept torque to the pivot. That allows a wheel to transfer energy from the table, to be done as work on the arm's mass, and whatever friction falls out of that. The prop is one means of generating a force from that energy.
With a plan to build a bogus wind generator scheme. I can say that is more than a hope, because TAD have not denied it. If it were a only a hope or indeterminate plan, they would have laughed it off at my expense.
And your say that, while avoiding the airport walkway test, which many would like to see if only because it would be interesting. Your string of mechanical failures denies your authority in predicting that the walkway will be to this or too that.
It will fail for sure, and that would leave you to explain why, after the behavior is known and recorded. Your best option is therefore to concoct reasons for the failure now, so that you may answer to them.
And that is also a version of a well worn physics question with freely available solutions.
http://demonstrations.wolfram.com/RollingBallInsideACylinder/
And recasting old ideas and puzzles, is where you get all your "kudos", here and elsewhere.
No pat answers to the question of a balloon and WS, so you let that one alone...
Last edited:
You are not going to take failure of your TM and trials very well, are you, Spork?
NB balloon nit-pick:
A normal, small balloon filled with air won't be NB. The air contained is slightly compressed (denser) than surrounding medium. Also, the membrane itself is clearly denser than surrounding air, hence, a mix of He and air would be required. Even then, as the balloon gets larger, its shape becomes less spherical because of density changes in altitude. A very large balloon will take on an inverted pear shape. Said shape may develop lift in a wind before it gets to windspeed, slightly skewing the data.
In another experiment, unrelated to balloons, but perhaps to the turntable:
I've toyed with making a floating magnet toy for years. Its a rascal. I thought I could replace the gyroscope with a cantilevered, counter-weighted, low c.o.g. toy; to prevent the inevitable flipping over. But no. The gyroscope behaves as a lighter version of the counter weight because of its angular momentum.
More on this if anyone wants. I know it isn't very clear, much less how it relates to the turntable experiment.
A normal, small balloon filled with air won't be NB. The air contained is slightly compressed (denser) than surrounding medium. Also, the membrane itself is clearly denser than surrounding air, hence, a mix of He and air would be required. Even then, as the balloon gets larger, its shape becomes less spherical because of density changes in altitude. A very large balloon will take on an inverted pear shape. Said shape may develop lift in a wind before it gets to windspeed, slightly skewing the data.
In another experiment, unrelated to balloons, but perhaps to the turntable:
I've toyed with making a floating magnet toy for years. Its a rascal. I thought I could replace the gyroscope with a cantilevered, counter-weighted, low c.o.g. toy; to prevent the inevitable flipping over. But no. The gyroscope behaves as a lighter version of the counter weight because of its angular momentum.
More on this if anyone wants. I know it isn't very clear, much less how it relates to the turntable experiment.
Dear god man you are persistent in your willful ignorance. In the first response to the Airport walkway suggestion it was made clear that the speed of the walkway was only 2 mph and the model needs a ws of 4 mph.
You ignored this and stated that the bb operated at lower speeds, even from a standing start. This totally ignores the ws when the bb was at a standing start, which I'm not looking up, but I am quite sure was well over 4 mph.
If you really can't understand this distinction then there is likely no hope.
Rolling Ball on Cylinder
I see what you are getting at here. The only thing I'm fuzzy on (I would have to see the vectors from the gyro moment) is that I think there needs to be a force ultimately generated to overcome gravity (I'll show a diagram, below) which needs to react against the surface to produce the couple to balance the forces. If the axis is not vertical then there seems to be slip to stay in the desired horizontal plane and the slip would be against the surface the force is reacting against would imply losses, sort of negating the initial conditions.
After looking at my own diagram, I'm not sure any slip is necessary. I would like to see the detailed analysis, but I can see from the diagram how this might just work!
As mentioned, I would have to brush up on my dynamics to do this mathematical justice, but I think I see where this is going. Very Clever.
I guess the ball has to be rolling just fast enough to create enough centrifugal force to hold it in place on the tilted axis and that solves the problem as long as the gyroscopic moment is large enough to overcome the resultant torque from the couple. Close?
(please, excuse my misspellings in my diagram.)
ETA: I see Humber posted a link to something that is actually cogent and relevant on this. Congratulations Humber!
Regards,
WindGrins
I see what you are getting at here. The only thing I'm fuzzy on (I would have to see the vectors from the gyro moment) is that I think there needs to be a force ultimately generated to overcome gravity (I'll show a diagram, below) which needs to react against the surface to produce the couple to balance the forces. If the axis is not vertical then there seems to be slip to stay in the desired horizontal plane and the slip would be against the surface the force is reacting against would imply losses, sort of negating the initial conditions.
After looking at my own diagram, I'm not sure any slip is necessary. I would like to see the detailed analysis, but I can see from the diagram how this might just work!
As mentioned, I would have to brush up on my dynamics to do this mathematical justice, but I think I see where this is going. Very Clever.
I guess the ball has to be rolling just fast enough to create enough centrifugal force to hold it in place on the tilted axis and that solves the problem as long as the gyroscopic moment is large enough to overcome the resultant torque from the couple. Close?
(please, excuse my misspellings in my diagram.)
ETA: I see Humber posted a link to something that is actually cogent and relevant on this. Congratulations Humber!
Regards,
WindGrins
Last edited:
NB Balloons
The unstated assumption is that the NB balloon will contain a lighter than air gas such as helium (as you mentioned) to overcome the mass of the envelope which is specifically heavier than air. One can achieve this by filling the balloon to an arbitrary level (short of popping) and counterweighting for any excess lift. See Spork's video (from his earlier post) in the car as that is what they did. This is clearly a small little balloon!
Windgrins
The unstated assumption is that the NB balloon will contain a lighter than air gas such as helium (as you mentioned) to overcome the mass of the envelope which is specifically heavier than air. One can achieve this by filling the balloon to an arbitrary level (short of popping) and counterweighting for any excess lift. See Spork's video (from his earlier post) in the car as that is what they did. This is clearly a small little balloon!
Windgrins
- Status