Down wind faster than the wind

[sol invictus]

They are irrelevant, of course. That is the point. The cart is oblivious to its surroundings or the velocity of the van. The outcome of the experiment is unfalsifiable.

No, humber - I just explained to you precisely how it could be falsified. Doing so would be very easy, if Newton was wrong - but it's not going to happen, because Newton was right .

You see, humber, the rest of us are satisfied that Newton (and Einstein, and every other physicist since) was correct. Instead, we're more interested in the behavior of this specific cart.

 

[Michael C]

Micheal_C,
As I have said, the velocity will be limited by the drag, but in the board case, it perhaps not so clear what I meant by the differential speed.

Put a dot on the big and small gears at 12 o'clock. If you move the cart forward, they will trace 2 sine waves, with a peak to peak value that is equal to the diameter of each gear which, are 2 and 1 respectively.

The dots will not trace sine waves, they'll trace trochoid curves.

Whether you make a correct graph with trochoids or an incorrect graph with sine curves is unimportant here: it does not in any way prove that the cart won't work. You might try making a graph of the movements of one of the pedals of a bicycle and a point on the edge of the back wheel of the same bicycle: it will be very similar to the curves traced by the wheels of Brian's cart. It's certainly an interesting exercise in geometry, but I don't think you will be able to use it to convince somebody that a bicycle can't work.

 

[humber]

No, humber - I just explained to you precisely how it could be falsified. Doing so would be very easy, if Newton was wrong - but it's not going to happen, because Newton was right .

You see, humber, the rest of us are satisfied that Newton (and Einstein, and every other physicist since) was correct. Instead, we're more interested in the behavior of this specific cart.

No, you did not.

"Falsifiability (or "refutability") is the logical possibility that an assertion can be shown false by an observation or a physical experiment"

The logical possibility does not exist, because the experiment presumes the outcome.
You have to show why your cart is capable of behaving other than Newton would predict, otherwise it IS a cart on a treadmill being driven around town, and not an indicator of windspeed.

You can' t do that because the forces that could, are isolated from the cart.

Newton, Einstein et al, have nothing to explain, but you do.

 

[humber]

The dots will not trace sine waves, they'll trace trochoid curves.

Whether you make a correct graph with trochoids or an incorrect graph with sine curves is unimportant here: it does not in any way prove that the cart won't work. You might try making a graph of the movements of one of the pedals of a bicycle and a point on the edge of the back wheel of the same bicycle: it will be very similar to the curves traced by the wheels of Brian's cart. It's certainly an interesting exercise in geometry, but I don't think you will be able to use it to convince somebody that a bicycle can't work.

No, they are circles, so they trace a sine relative to the centers. They will have periods when they move opposite to the direction of travel. Rectification of that waveform would not change the argument, as long as I kept note of the signs.

You see that you must maintain a constantly shifting phase, to avoid being averaged out. From the above, you should realise that all wheels are transmissions. They shift friction about. The average velocity of a circle is zero, but the acceleration is constant.

I used the sines to avoid talking about the consequences of control of the force required to maintain a constant velocity for both. Just and idea of the mechanism. Pushing and pulling, and equating dynamics with statics, is a hard bias to overcome. I seems that there is but one way to express a point, Micheal_C.

You can kill my argument dead by showing that you can apply a constant force, and gain an increase in velocity of the cart. Acceleration is always required to keep the gain.
Make graphs of displacement and acceleration and velocity over time. Try and find the sort of pull (constant force, constant velocity. constant power, that will allow you a constant velocity.

 

[sol invictus]

No, you did not.

"Falsifiability (or "refutability") is the logical possibility that an assertion can be shown false by an observation or a physical experiment"

The logical possibility does not exist, because the experiment presumes the outcome.

Nonsense. For the third and final time, if the cart's behavior is affected by the van's speed, Newton, Einstein, and every other physicist was wrong and their equations falsified. Such a thing is logically possible - in fact it's not just possible, many people prior to Newton, and many uneducated people (like you) after, would expect that to happen.

Again, as an example: if when the van is stopped the cart moves forward on the belt as in the videos, but when the van is moving at 10 mph it moves backward, Newton was wrong.

The fact that that does not happen, and has not happened in countless physics experiments over the last four centuries, is extremely strong evidence that Newton and Einstein were right - and humber is wrong. If we accept Newton as correct we then have an extremely powerful tool - we don't need to do experiments at windspeed outside, we can do them inside on a treadmill.

 

[humber]

Nonsense. For the third and final time, if the cart's behavior is affected by the van's speed, Newton, Einstein, and every other physicist was wrong and their equations falsified. Such a thing is logically possible - in fact it's not just possible, many people prior to Newton, and many uneducated people (like you) after, would expect that to happen.

Again, as an example: if when the van is stopped the cart moves forward on the belt as in the videos, but when the van is moving at 10 mph it moves backward, Newton was wrong.

The fact that that does not happen, and has not happened in countless physics experiments over the last four centuries, is extremely strong evidence that Newton and Einstein were right - and humber is wrong. If we accept Newton as correct we then have an extremely powerful tool - we don't need to do experiments at windspeed outside, we can do them inside on a treadmill.

Nope, completely wrong. The fact that is is all things to all men, means that it has no specificity. It is not falsifiable, because it has no valid, let alone unique, outcome.
From the perspective of the observer, (your game, not mine) exactly the same result is obtained regardless of any of the relative velocities.
That means that it is not selective for that outcome. Reaction to acceleration is common to all other objects that are also not models of a cart at windspeed.

Newton would agree with me. It's a cart on a treadmill being driven around town. Feynman would probably just laugh at the idea that it could be otherwise.

 

[Thabiguy]

Humber quote of the day:

You can kill my argument dead by showing that you can apply a constant force, and gain an increase in velocity of the cart.

 

[H'ethetheth]

No, you did not.

"Falsifiability (or "refutability") is the logical possibility that an assertion can be shown false by an observation or a physical experiment"

The logical possibility does not exist, because the experiment presumes the outcome.
You have to show why your cart is capable of behaving other than Newton would predict, otherwise it IS a cart on a treadmill being driven around town, and not an indicator of windspeed.

You can' t do that because the forces that could, are isolated from the cart.

Newton, Einstein et al, have nothing to explain, but you do.

No you really have this the wrong way, and I don't know why.

I'll try something else:
You agree that the indoor conveyor belt and the van setup are equivalent, if I understand you correctly.

Now, take the van setup and

(1) replace the van by a box on a conveyor belt moving 10 mph. I hope you'll agree this is indifferent to the cart.
(2) Since the air surrounding the box is standing still relative to the box, we can dispense with the box. No additional forces will act on the cart.
(3) The top of the treadmill is moving backward at 10mph relative to the large conveyor belt, which is moving 10 mph forward.
Therefore the top of the treadmill is always stationary relative to the earth.
Thus, we can dispense with the two conveyor belts without creating additional forces on the cart.

So we conclude that the dynamics of the conveyor belt and the street with wind are identical from the frame of reference of the cart, i.e. no wind and moving ground.

But you don't seem convinced that this is true, so I'll try to explain how to falsify the treadmill as a model for the street. If the treadmill is not a representative model of the street we would expect to find things like:
Objects that move at wind speed experience relative wind, or
To an observer on an object moving with the wind at wind speed, the ground appears to pass by at a speed different from the wind speed.

I agree to you that these things are quite improbable, but they would very much falsify this model. Since neither is the case, we can safely say that Newtonian and Einsteinian physics allow the treadmill as a model for a windy street.

ETA: Of course, if you want to be a complete nitpick, the treadmill should be large compared to the cart to account for boundary layer effects, but I assure you, these effects do not significantly affect the cart's operating principle.

 

[H'ethetheth]

Humber quote of the day:

I missed that one. He might be on to something.




maybe he's zombie Aristotle.

 

[humber]

I missed that one. He might be on to something.




maybe he's zombie Aristotle.

Yes, see if you can refute my claim. See if you can apply a constant force or velocity to the board or track and maintain a constant speed gain. The apparent speed gain is acceleration.
When you do, and realise the consequences, my remark about the operator manipulating the force, will all make sense to you.

Then you can post an apology.

Thabiguy,

thabiguy/H'ethetheth?
maybe he's zombie Aristotle.

The idea behind the notion of the philosopher's zombie, is exactly the mistake you are making with your "equivalence" idea. Ironic, eh? The feint print is therefore justified.

 

[ynot]

More independent results coming in.

Have no idea who these guys are -- they just sent me a note to look at their videos.

http://www.youtube.com/watch?v=9S2HHwfcz9Y

http://www.youtube.com/watch?v=A9owATX8DoI

JB

Why are these guys testing their cart at the very end of the treadmill? By their own admission they know there is a “pit” there. How big is the distance between the roller and the flat surface the belt runs over? It’s hard to get exact detail from observing such a film but it looks to me that the cart (being fairly heavy) makes and indentation in the belt. And is the surface flat for it’s total length or does it taper off slightly at the end? It looks to me that the wheels are running in quite a large “pit”. Why don’t they test their cart in the center of the treadmill where we can all be certain there is no “pit”? They have a cart of a size that should perform well in an outside wind, why haven’t they tested it there and posted the video? Are they testing to see if it works, or to make it "work"?

I have tested my first cart on a treadmill but it didn’t work. This was obviously due to design faults and not the principle so will refine and redesign to improve it.

 

[humber]

No you really have this the wrong way, and I don't know why.

I'll try something else:
You agree that the indoor conveyor belt and the van setup are equivalent, if I understand you correctly.

I don't agree that the conveyor belt is an indicator of windspeed. The van test adds nothing in rebuttal.
But, I can accept it for the purposes.

Now, take the van setup and
(1) replace the van by a box on a conveyor belt moving 10 mph. I hope you'll agree this is indifferent to the cart.
(2) Since the air surrounding the box is standing still relative to the box, we can dispense with the box. No additional forces will act on the cart
(3) The top of the treadmill is moving backward at 10mph relative to the large conveyor belt, which is moving 10 mph forward.
Therefore the top of the treadmill is always stationary relative to the earth.
Thus, we can dispense with the two conveyor belts without creating additional forces on the cart.

So we conclude that the dynamics of the conveyor belt and the street with wind are identical from the frame of reference of the cart, i.e. no wind and moving ground.

No, you have isolated one variable, velocity, and then inferred its existence to be unnecessary.
A moving belt is not a road. To make your case, you need to emulate all of the characteristics, and not just an idealised wind called 'velocity'.
Not that is is all relevant, because the basic logic is flawed, but the principle of equivalance, that of equally valid perspectives, is posited upon the idea that all relationships between those relative objects remain the same. So you would need to compare the treadmill in a van, with another of the same, but not a cart in the wind.

But you don't seem convinced that this is true, so I'll try to explain how to falsify the treadmill as a model for the street. If the treadmill is not a representative model of the street we would expect to find things like:
Objects that move at wind speed experience relative wind, or
To an observer on an object moving with the wind at wind speed, the ground appears to pass by at a speed different from the wind speed.

It is also true that motionless objects in still air, have zero relative velocity.

I agree to you that these things are quite improbable, but they would very much falsify this model. Since neither is the case, we can safely say that Newtonian and Einsteinian physics allow the treadmill as a model for a windy street.
ETA: Of course, if you want to be a complete nitpick, the treadmill should be large compared to the cart to account for boundary layer effects, but I assure you, these effects do not significantly affect the cart's operating principle.

It is interesting that the same canards are raised at each turn.
The problem has at its centre, a fallacy, a falsely derived syllogism.

A has the characteristic C
B has the characteristic C
A and B are the same.

Air around a windspeed model is still.
Air around a model at rest is still.
If air is still, the model is at windspeed.

ETA: let's not forget;
Wind moves
Belts move
Belts are the same as wind

Please tell me by observation of the cart, why I shoud prefer your version to "just a model spinning its propeller in still air while being driven by a belt"
Take four treadmills and place them at 90degrees to each other. Drive as usual. Which one is telling the truth? (No peeking out of the window)

Add a camera to the devices in the van, and one a stationary treadmill at home, and compare. Apart from secondary effects(engine noise, vibration) how can you tell which is which?

As a system, the van and treadmill must be mutually coupled. If the belt is providing the energy to drive the cart to windspeed, how are the treadmill and van motors coupled?

 

[Michael C]

No, they are circles, so they trace a sine relative to the centers. They will have periods when they move opposite to the direction of travel. Rectification of that waveform would not change the argument, as long as I kept note of the signs.

No, once more: a rolling circle does not trace a sine wave. A sine wave is produced by an oscillator moving directly up and down the y-axis while progressing with uniform velocity along the x-axis. A point on the edge of a rolling circle does not progress with uniform velocity along the x-axis. Did you look at the link I gave?

Here are a few links concerning the curves made by advancing rolling circles:

http://en.wikipedia.org/wiki/Trochoid
http://www.geom.uiuc.edu/docs/reference/CRC-formulas/node34.html
http://www.2dcurves.com/roulette/roulettec.html
http://www.xahlee.org/SpecialPlaneCurves_dir/Trochoid_dir/trochoid.html

If you still think a point on one of the circles will trace a sine wave, may I (once more) suggest that you make the cart and try it out?

 

[humber]

No, once more: a rolling circle does not trace a sine wave. A sine wave is produced by an oscillator moving directly up and down the y-axis while progressing with uniform velocity along the x-axis. A point on the edge of a rolling circle does not progress with uniform velocity along the x-axis. Did you look at the link I gave?

Here are a few links concerning the curves made by advancing rolling circles:

http://en.wikipedia.org/wiki/Trochoid
http://www.geom.uiuc.edu/docs/reference/CRC-formulas/node34.html
http://www.2dcurves.com/roulette/roulettec.html
http://www.xahlee.org/SpecialPlaneCurves_dir/Trochoid_dir/trochoid.html

If you still think a point on one of the circles will trace a sine wave, may I (once more) suggest that you make the cart and try it out?

Micheal_C,
You, Brian-M, and Myriad, seem more logical than those I refer to as the mice. However, you do appear to behave like them sometimes.

I don't just say stuff, in order to give you a hard time. Yes, I do know what a trochoid is, and yes I looked at the link, but you didn't take note of what I said. I said "rectified". Take a look at the two equations in the link Remove the constants. Guess what, it's a sine wave. If you turn an AC generator, then you get a sine wave.
When the dot is turning above the axis line, it creates, the top half of the sine wave. The next 180 degrees are in the opposite direction, so they are negative. The motion of the axis cancels out, because they are both doing that. They are joined together. It is the differential motion that counts.
I did think that when I posted the graphs, someone might say that if I average the white trace, that too is zero, so no wheel can travel, and it appears that you did. No, the difference is that the "gain" has an average of zero. You need a constant change in velocity to support it incrementally. Therefore, the difference can only "exist" when accelerating. No device can beat F=ma, wheels don't count.
Forget it then, it was a mistake to raise the possibility.

Whether you make a correct graph with trochoids or an incorrect graph with sine curves is unimportant here: it does not in any way prove that the cart won't work.

You raise a point, but put in a caveat of "unimportant", just in case,eh?

If you don't want to know, then don't pretend that you do.

You misunderstand, me. If you are right, I will agree.
I did take the time to work out the graphs I suggested you do, because the idea is seductive. I can be fooled by my "intuition".
I don't think I have made a mistake, because I balanced not only the forces, but the energy. Perhaps I am wrong, you can do the same, and see.
If however, if you insist that forces are magical, then that is a problem.
Use models. A constant velocity 'puller' does so all the time. Load does not affect it.
A constant force 'puller', always maintains a constant force regardless of velocity. The other is a constant power, that adjusts the force and velocity, to maintain that same power.

Now, imagine pushing a load with a constant velocity device. The object must accelerate to that velocity instantaneously, correct? The pusher is relentless. On the other hand, in practice, that will take time.
If you don't follow through, you will see that bit, and not the final state that it must assume.

 

[H'ethetheth]

I don't agree that the conveyor belt is an indicator of windspeed. The van test adds nothing in rebuttal.
But, I can accept it for the purposes.

No, you have isolated one variable, velocity, and then inferred its existence to be unnecessary.
A moving belt is not a road. To make your case, you need to emulate all of the characteristics, and not just an idealised wind called 'velocity'.
Not that is is all relevant, because the basic logic is flawed, but the principle of equivalance, that of equally valid perspectives, is posited upon the idea that all relationships between those relative objects remain the same. So you would need to compare the treadmill in a van, with another of the same, but not a cart in the wind.

I just did, and then showed you that all of the other components of the van are dispensable while preserving the dynamics of this system.

It is also true that motionless objects in still air, have zero relative velocity.

I'm not sure why you say this, but it is in fact true.

It is interesting that the same canards are raised at each turn.
The problem has at its centre, a fallacy, a falsely derived syllogism.

A has the characteristic C
B has the characteristic C
A and B are the same.

Air around a windspeed model is still.
Air around a model at rest is still.
If air is still, the model is at windspeed.

A couple of things: The first syllogism, though indeed invalid, has nothing to do with the equivalence of treadmill and cart at windspeed.
The specified case is not an example of the abstracted syllogism; It's imprecisely formulated, and still has nothing to do with the matter at hand.
For instance, the second premise is just a special case of the first, namely for windspeed equals zero.
This makes the syllogism valid and the conclusion true, though trivial, since it is just a reformulation of the one premise.

What we should actually be interested in, however, are the relative speeds between the air, the cart, and the surface. Do these relative speeds differ between the treadmill and a cart moving over a road at windspeed? Let's see:

Outside:

V_cart - V_air = V_wind - V_wind = 0
V_cart - V_road = V_wind - 0 = V_wind
V_air - V_road = V_wind - 0 = V_wind

Inside:

V_cart - V_air = 0 - 0 = 0
V_cart - V_road = 0 - V_treadmill = - V_treadmill
V_air - V_road = 0 - V_treadmill = - V_treadmill

This means that for any V_treadmill = - V_wind , the two situations are identical. That is, for every wind speed, we can set a treadmill speed that results in equivalent dynamics.
Like I said before, this ignores differences in the boundary layer flows, but does not affect the working principle of the cart. Both the treadmill and the road develop a similar boundary layer flow, and the bigger the treadmill, the more alike the two will become.

ETA: let's not forget;
Wind moves
Belts move
Belts are the same as wind

This is not what we are saying. In similarly short wording I would say:

Air moves over road
Velocity is relative.
Road moving in still air is the same as air moving over road.

And the modelling consists of:
Belt moving in still air is equivalent to road moving in still air.

Please tell me by observation of the cart, why I shoud prefer your version to "just a model spinning its propeller in still air while being driven by a belt"
Take four treadmills and place them at 90degrees to each other. Drive as usual. Which one is telling the truth? (No peeking out of the window)

I will tell you no such thing. In fact, I'm trying to tell you that they are all equivalent.

Add a camera to the devices in the van, and one a stationary treadmill at home, and compare. Apart from secondary effects(engine noise, vibration) how can you tell which is which?

You can't, that is what equivalence means. I'm still not sure what your problem is.

As a system, the van and treadmill must be mutually coupled. If the belt is providing the energy to drive the cart to windspeed, how are the treadmill and van motors coupled?

This does not make sense. The cart is not driven up to windspeed on the treadmill. It's already at windspeed. Putting the cart on the treadmill is equivalent to running as fast as the wind, then putting the cart on the ground.
What provides the energy is, as sol invictus pointed out, the difference in speed between the surface and the air. In the treadmill this difference is maintained by the treadmill motor; outside, this difference is maintained by the wind.

 

[Michael C]

I don't just say stuff, in order to give you a hard time. Yes, I do know what a trochoid is, and yes I looked at the link, but you didn't take note of what I said. I said "rectified". Take a look at the two equations in the link Remove the constants. Guess what, it's a sine wave. If you turn an AC generator, then you get a sine wave.
When the dot is turning above the axis line, it creates, the top half of the sine wave. The next 180 degrees are in the opposite direction, so they are negative. The motion of the axis cancels out, because they are both doing that. They are joined together. It is the differential motion that counts.

What you said was this:

Put a dot on the big and small gears at 12 o'clock. If you move the cart forward, they will trace 2 sine waves, with a peak to peak value that is equal to the diameter of each gear which, are 2 and 1 respectively.

You didn't say anything about "rectified". The dots will both trace trochoids, not sine waves. There as absolutely no doubt about this. Do you agree, or not?

 

[spork]

Humber quote of the day: "You can kill my argument dead by showing that you can apply a constant force, and gain an increase in velocity of the cart."

Nice catch bigguy!

This just in...

F=MA NO LONGER TRUE

 

[humber]

Nice catch bigguy!

This just in...

F=MA NO LONGER TRUE

Yes, there's a typo there. The rest makes the context clear.

I am pleased that such trivia causes you to celebrate.

 

[ThinAirDesigns]

Humber:

You can kill my argument dead by showing that you can apply a constant force, and gain an increase in velocity of the cart.

Humber:

Yes, there's a typo there.

Please, show us the "typo".

Change the spelling of a word, change a point of punctuation or invert a pair of letters that will take the meaning of that sentence and make it correct.

Please, PLEASE do. I double dog dare you.

JB

 

[Michael C]

Today I made my own version of a moving machine where output is in the same direction as input and faster than input. The machine itself is nothing more than an empty cotton reel: the motive force comes from the movement of a strip of paper over a flat surface.

I call it the ATPFTTP machine because it goes Along The Paper Faster Than The Paper.

Here it is on YouTube:



I will gladly send detailed plans to anyone who wishes to make one