Yes, jjcote, good choice. If 5m/s were used, that will create another set of symmetrical balance points around 10m/s. Not a problem for real wind though.
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Split Thread The validity of classical physics (split from: DWFTTW)
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Yes, jjcote, good choice. If 5m/s were used, that will create another set of symmetrical balance points around 10m/s. Not a problem for real wind though.
Brian-M
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Of course there's a problem with your perception! It's obvious that the kinetic energy transferred to your kite by running is initially being converted into potential energy, after which the gravitational pull counteracted by the drag from the air is acting like a friction balance allowing the kite to "hover" in place. Over time you're kite will slowly descend to earth as the kinetic energy is gradually lost lost from friction. Being pulled through the air is not the same as being pulled by the air! Coriolis force will be different, as will the moon's gravitational pull on the string. The kite has experienced acceleration, and acceleration is absolute. The wind has no kinetic energy, and so cannot support the kite as it's being pulled. If you had bothered to run with the kite for three or four hours, the difference in performance would have been obvious. [/HUMBERVISION]
Take the goldfish's advice. One with phone must be an extraordinary creature.
ETA:
The insults are often cryptic. That's the point. Flat-out insults are commonplace.
Both my claims and insults generally require knowledge of the reader.
A pointless quiz, that adds nothing to the matter at hand.
Perhaps you would instead like to support your own ideas ?
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Brian-M
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...Where as a LACK of motion between a cart and the air at windspeed is REAL, but one on a treadmill in still air is not.
The first has no KE wrt the the ground. If I was passing by in a balloon (at windspeed, of course) it WOULD have KE wrt to me. If I collided with it, I'd feel it. That's KE. Similarly, If I was staionary in my balloon in still air, and the kite hit me, I'd feel it to the exact same degree.
Something about velocity being relative.....
Brian-M
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You're right! I tried travelling at a different velicity to myself AND IT WORKED!. I can't tell you how pleased I am. I'm quite literally beside myself with glee.
I think we should drop the physics test and just offer Humber a math test. Nothing complicated, just some basic vector geometry involving both postive and negative values.
Oh my goodness master...
I am completely humblerd by your reply to John Freestone. As always, my pitiful attempt to foretell your words came to naught. I am truly but a pebble at the foot of the mountain and so worry still about the sounds of trees falling if I am not there to hear them...
Now, please forgive me for my impertinence, but even after meditating on it I have another question for you:
Say a man, a very careful and precise man (perhaps even yourself), was to kneel on a road in a wind not unlike those being discussed, and using the very best measuring tools and techniques, record the speed and direction of the flow at a series of heights starting from very near to the surface and building up through the boundary layer and then stopping only when into the the clear air above. He may record these in a table with three columns, labelled height, direction, and speed, and of course he has positioned himself and his equipment as to not interfere with the flow.
Now the man may repeat this exercise while kneeling on a large and long treadmill with comparable surface to the road but this time with the belt moving beneath the still air overhead at the same speed as the air passed over the road before. He measures at the same heights above the belt as he did before above the road and records again the direction and speed at each level. He is a fast worker and completes the task before falling off the end of treadmill.
How then should we expect the two sets of recorded values to compare?
Should they be the same, like two peas in a pod? Would they be more like apples and oranges? Or would the comparison be as disparate as if a pebble fell beside a mountain?
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Now to the boundary layer....
The belt is turning such that it's surface is passing a stationary observer (wrt the earths surface)right to left. It will cause a boundary layer that will ALSO pass right to left. On the surface, the air will move at belt speed. At any point ABOVE the surface, it will STILL move right to left, but at a speed slower than the belt. Right to left at a speed lower than the belt means left to right wrt the surface of the belt.
Just like John (and everyone else!!) has been trying to tell you.
So blindingly obvious, it's amazing you can even TRY and argue it!
If it were not so, the air would be traveling FASTER than the belt, and we'd have invented perpetual motion.
No wonder you have so much time to post, the Humberverse produces it's own energy!!!!
The belt is turning such that it's surface is passing a stationary observer (wrt the earths surface)right to left. It will cause a boundary layer that will ALSO pass right to left. On the surface, the air will move at belt speed. At any point ABOVE the surface, it will STILL move right to left, but at a speed slower than the belt. Right to left at a speed lower than the belt means left to right wrt the surface of the belt.
Just like John (and everyone else!!) has been trying to tell you.
So blindingly obvious, it's amazing you can even TRY and argue it!
If it were not so, the air would be traveling FASTER than the belt, and we'd have invented perpetual motion.
No wonder you have so much time to post, the Humberverse produces it's own energy!!!!
The Humber likes sarcasm, John. It's funny.
The windspeeds that you want are the same as mine.
Add the apparent observer view to mine, to get yours, then subtract them again to get the correct answer. Do you see why I don't answer the question?
I think Sol_invictus should give it a go. Should be fun not to see the "gaps filled" but the attempts to patch up the holes in the treadmill.
John, the multiple flaws in your diagram give you away. The master will tear you to shreds if you let him see those. For one thing the right hand panel shows the differential between air at head height and the belt below as 20 m/s. Attempting to fill in the missing values in those circumstances would be like playing Russian roulette. The direction of that differential isn't even specified. Meanwhile the diagram on the left has unexplained gaps. Perhaps your omission of 5 is as I explained to mender earlier. Is this meant to be a trap, the old good-cop, bad-cop routine? The laws of physics have a symmetry but 10 - 7 is undefined in your world? You will most likely be ignored for tastier targets.
I don't know why you mention sarcasm. To understand another you must stand in their shoes. Communication without understanding is futile. So is resistance. Join us now - the numbers are with us!
Maybe Clive, if your posts didn't contain so much "see humber you've gone and made a mistake again", then you may better see where you are wrong.
A lot of talk, but no refutation. No solid arithmetic rebuttal, just more "observer" loaded rhetoric?
Yes to both, SD.
No. I can do that on my head. The problem is not there SD. You are all making grievous errors of first principles of science let alone physics.
No questions, correctly answered or otherwise, will help either of us because if for no other reason, they assume that you already accept that fundamental knowledge.
A qualified engineers (working for an independent contracting supplier) made such a blunder; one that beggars belief, and apparently operated by magic.
Before I had completed giving the description of the problem to an optics engineer, he threw his head back, burying his face in his hands. Why?
Because he realized, that after waiting a year for the supply that would power his laser, he had been delivered a practical joke.
Qualifications are just paper, and like paper money, may not always hold their face value. And yes, the treadmill is one such joke.
I too have noticed that. Care to play poker?
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That endorsement from humber is almost as good as getting the nobel prize for general knowledge!
There is no such prize.
You must keep with the same datum. "Winspeed" is an notional inference from the fact that the belt going backwards. Therefore you must that 'translation' again for the belt.
Yes, but not it seems for geared winspeed carts, Brian-M.
If there is no force or drag at water or windspeed what is to stop water going faster than itself?
Yes, everything is everything w.r.t itself.
No, you are missing one step. Arithmetic shows the error. See below.
The cart's direction, like the wind's, is positive and moving left to right.
The flow is 4m/s slower than the wind, but moving right to left.
Hence -6m/s w.r.t the cart.
6m/s right to left. Check
OR
Wind = 0 +10 = 10 The observer wind is positive going left to right.
Flow = -6 +10 = 4 Belt flow is now referred to the same wind, left to right
4m/s left to right. Superposition of flows.
No. Winspeed is already "0" because the belt is -10
Easy![/QUOTE]
Lax!
I don't think so. But it does describe your support for it.
H'ethetheth
fishy rocket scientist
What?! No, I want to hear about your authority on the matter, because you claim you can ace mine.
If you dare me to ask a colleague, then yes, I need a colleague.
Okay, the water tunnel for fish I designed is a fish wheel flow tank. A guy named Bainbridge (1958 and about the paper) came up with the idea in the 1950's and we found out about that halfway through the design process. It's basically an annular fish tank that spins while keeping the fish in place. I can think of at least two ways it's like the treadmill, but you're going to tell me it isn't, so go ahead.
I'm not sure the paper is freely accessible, but the article about it should be. If not, I'll post a picture of my own version.
Sorry, authority does not work that way. Authority means that it matters what ass arguments are pulled from. I want to know how your authority puts mine to shame, since you assurred me it would, and I'm honestly curious.
John Freestone
Graduate Poster
Ah yes. When I went to bed last night, I had actually deluded myself that humber might just find my approach incontrovertible. I'm seeing the doctor today anyway, so I'll mention it.
Is that the one in Scienceville, near the Empirical State Building?
But surely you do understand that wind velocities change for an observer, depending on whether they travel and at what velocity w.r.t. the wind. Surely you also know that the forces on a body from that wind will change with their relative velocities. Surely you know that these are the velocities we are interested in, those experienced by the thought-experiment observer on the belt, since they are the forces "experienced" by a cart. Surely also those were the velocities you were eager to show involved a reversal within the boundary layer, this being the basis of one of your contentions that the cart on a treadmill is significantly different from one blown along a road outside. Surely also, it is those relative velocities that would affect your paddle, and thus pertained to your earlier calculations. Surely, we were trying to work out the very same values, even though we disagree about them.
Or was your paddle magical, as I suspected, and able to measure the velocity of a wind relative to the ground when it is itself moving relative to the ground?
They absolutely obviously will not. But if I obtained some under strict scientific scrutiny and subjected them to years of peer review (not that anyone would be interested in measuring the speed of things we already know), you would still contradict the conclusion.
You forgot "QED". But your solution wasn't the same for all observers. Your paddle spun backwards, because the flow on a treadmill was reversed compared with that on the ground! I (and several others) corrected your mistakes, and WE showed that the flows were identical, both between scenarios and no matter whether moving or at rest through the wind, since its relative velocities do not change.
My diagram shows precisely what you said an observer feels - 10 back of head, 6 lower down from front. You were quite clearly working out what that observer would experience. Surely, you're not going to do that low trick of pretending you were stating something different from what everyone thought you were stating? Not you, humber!
No, the flow is with the belt. That is negative. The premise of the treadmill is that the road/belt moves backwards w.r.t the cart. The tailwind is positive.
No. -6m/s If the cart is moving in the positive direction the belt is negative.
Constant difference between wind and flow of 4m/s, independent of observer velocity. Where observer motion with the wind is positive.
NO!10m/s(+2m/s) = 12m/s wind to observer at 2m/s (Flow is left to right)
-6m/s (+2m/s) = -4m/s observer in flow at 2m/s (Flow is right to left)
16m/s difference.
Yes, faster than the wind! How? Relatively opposite flows, the vary foundation of your claim! an "Inconvenient Truth"
(1)All motion, wind or cart, is positive going left to right, if you say the cart is going forward left to right.
(2)The belt and belt winds, are therefore negative, going right to left.
When I do it, yes.
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