Merged DDWFTTW in a “Real” Wind

[humber]

LOL. I fool might think that, yes.

JB

The rotation changes direction, and frame stepping shows that can only only be the results of a true headwind.
Nothing changes the fact that you knowingly tested for ddw, in conditions that you knew were not. The data was available to you.

 

[humber]

He still thinks the deviation gauge was a streamer.
He thinks that everybody didn't already know that winds don't stay steady in one direction.

Meaning the Spork did not have an indicator, so had no intention of following the wind, because it had already been established by prior tests, that the cart did badly when ddw.

He thinks that the record setter shouldn't be allowed to choose the best run.

For the one trial that even looks partly convincing. There are many trials that contain headwinds and changes of 60degrees or more.
The plan undertaken was to travel a fixed nominal downwind heading, and wait until such time that the wind changed enough to power the cart. From all the trials that did not work, there remained were few that did, and the contestant was allowed to select them.

LMAO
He thinks what happened after the record was set is relevant at all.

40 degrees deviation: component. Not RMS, not average, but component.
Not even remotely ddw.

 

[spork]

Personally, I don't see the point of arguing with humber about this (or anything). I guess there's a small entertainment value, but what will be far more entertaining are the two possible outcomes:
- He'll never send a report to NALSA despite all his bold claims.
- If he does, we can then watch the hilarity ensue when NALSA tells him to go pound sand. And we'll get more than a few giggles out of the report when I post it here for all to see.

In fact, I don't think he'll send a report for that reason alone. As soon as he did, he could no longer control it in any way. We would all get to see what he thinks passes as physics and logic. I just don't believe that's a risk he's prepared to take.

 

[profpangloss]

Thanks. I understand it now.

I used equation (1) on that page, plugged in 160 N for the thrust, 4.8768 m (16 feet) for the propeller diameter, 2 m/s for the air speed, and 1.225 kg/m³ for the air density, then solved the resulting quadratic equation for delta-v. I got 2.24 m/s, which matches well with profpangloss's 2.2 m/s.

Right. I'm sorry I didn't get back to you sooner on your question about that. That equation for propeller thrust is just F =ma, where the delta-v is the acceleration, and all the other terms give you the mass of the air being accelerated. Now that you have confirmed delta-v to be 2.2 m/s, you can calculate the air mass as ~ 72 kg.
This boils the issue down nicely as to how that 72 kg mass of air, moving at 7 m/s (in the example we were examining) is able to impart kinetic energy to the 295 kg massive cart, moving at 9 m/s? The only way that can happen is by doing work, using a propeller for example, but to do that work you need to use energy. A small aircraft with an engine can burn some fuel, a source of energy, and that enables the propeller to do some work on the air and generate thrust. Where is the energy for the cart to use to do work on the air to generate thrust? Sometimes the carteers claim the energy comes from the "ground moving under the cart". Yeah sure! Just to head that one off at the pass, let's stay in the frame where the ground is stationary-it has no energy in that frame. The wind has less kinetic energy than the cart (at least the 72 kg we are concerned with) so we still need to do work on that wind. I have shown that using the cart's own kinetic energy will not achieve anything, as you lose more than you can gain, unless you want to claim over unity. So the ground is out, the cart's KE is out, what is left? Now the carteers say the wind itself will provide the energy needed for the propeller to do the work in order to get energy from the wind! That's a vicious circle, otherwise known as perpetual motion, and is nonsense.
The simple truth of the matter: the cart, like every other wind powered craft, cannot go DDWFTTW, and the NALSA data shows without a doubt that it did NOT do so.
What is confusing people is the treadmill, which is said to be exactly the same as a cart on a road going DDWFTTW. In reality, the treadmill is an example of one piece of rotary machinery driving another piece of rotary machinery and all the energy is coming from the electric motor. It has nothing at all to do with wind power. Once you stop being fooled by the treadmill, and do a little math, and examine the NALSA data with an eye on the truth, you will find that Humber is the one who has this right and the carteers are not just wrong, but maliciously wrong.
All I ask you to do, all I ask anyone to do, is examine the facts and don't give in to the pack pressure that if you don't "get it" somehow you are an idiot.

 

[humber]

Personally, I don't see the point of arguing with humber about this (or anything). I guess there's a small entertainment value, but what will be far more entertaining are the two possible outcomes:
- He'll never send a report to NALSA despite all his bold claims.

I am still waiting on a few details from NALSA, but I already have enough to show that your cart is a sham, so they will get the report one way or the other.

- If he does, we can then watch the hilarity ensue when NALSA tells him to go pound sand. And we'll get more than a few giggles out of the report when I post it here for all to see.

You do that.

In fact, I don't think he'll send a report for that reason alone. As soon as he did, he could no longer control it in any way. We would all get to see what he thinks passes as physics and logic. I just don't believe that's a risk he's prepared to take.

Any more leaves left on that lucky clover, Spork?

 

[69dodge]

Right. I'm sorry I didn't get back to you sooner on your question about that.

No problem. But I wonder if you could comment on this post of mine as well.

That equation for propeller thrust is just F =ma, where the delta-v is the acceleration, and all the other terms give you the mass of the air being accelerated. Now that you have confirmed delta-v to be 2.2 m/s, you can calculate the air mass as ~ 72 kg.

Yes.

This boils the issue down nicely as to how that 72 kg mass of air, moving at 7 m/s (in the example we were examining) is able to impart kinetic energy to the 295 kg massive cart, moving at 9 m/s? The only way that can happen is by doing work, using a propeller for example, but to do that work you need to use energy.

Ok.

A small aircraft with an engine can burn some fuel, a source of energy, and that enables the propeller to do some work on the air and generate thrust. Where is the energy for the cart to use to do work on the air to generate thrust? Sometimes the carteers claim the energy comes from the "ground moving under the cart". Yeah sure!

I don't see anything wrong with looking at it that way, provided we are consistent about staying in the frame of reference in which the ground is moving.

Just to head that one off at the pass, let's stay in the frame where the ground is stationary-it has no energy in that frame.

That's ok too, of course. We can pick any frame of reference to work in, and we should get the same answer.

The wind has less kinetic energy than the cart (at least the 72 kg we are concerned with) so we still need to do work on that wind.

I don't see why this is true. Why are the relative amounts of kinetic energy at all relevant? See this post by Michael C for a simple counterexample.

It is true that the air is moving slower than the cart, and therefore, the propeller needs to be spinning in order for it to receive energy from the moving air. Some energy is required to spin the propeller, but I see no reason why the amount of energy it subsequently gains from the air can't be more than the energy required to spin it.

I have shown that using the cart's own kinetic energy will not achieve anything, as you lose more than you can gain, unless you want to claim over unity.

I don't think you've shown that. See the post of mine that I referred to above.

What is confusing people is the treadmill, which is said to be exactly the same as a cart on a road going DDWFTTW. In reality, the treadmill is an example of one piece of rotary machinery driving another piece of rotary machinery and all the energy is coming from the electric motor. It has nothing at all to do with wind power.

You can say "the energy is coming from the electric motor", but that doesn't explain in any detail why the electric motor drives the cart forward rather than backward. After all, the tread of the treadmill is moving backward. Why doesn't the cart simply follow the tread backward?

I believe that as you analyze the cart on the treadmill more and more carefully, it will start to seem more and more like the same cart on the ground in a wind. All the relative motions are the same. All the torques and forces are the same. So, why would the cart not behave in the same way?

 

[Jack by the hedge]

From all the trials that did not work, there remained were few that did, and the contestant was allowed to select them.

So what?

 

[humber]

I don't see why this is true. Why are the relative amounts of kinetic energy at all relevant? See this post by Michael C for a simple counterexample.

It isn't a counterexample, but something else, but if the collision is elastic and ideal, the ball will stop dead.
Vball = 10m/s
Vtruck = 5m/s
If the mass of the truck is large compared to the ball, it will bounce off
at (-Vball+2Vtruck) = 0

You can say "the energy is coming from the electric motor", but that doesn't explain in any detail why the electric motor drives the cart forward rather than backward. After all, the tread of the treadmill is moving backward. Why doesn't the cart simply follow the tread backward?

It does neither. In one of the videos the prop is removed, but the cart only drifts back relatively slowly. It does not instantly move back at the speed of the belt because of the wheels, and the angular momentum. Add more rotating mass, and it will drift ever slower backwards. All that is needed is a means of maintaining the initial energy stored as it was brought to speed by hand. It's about 1J in the case of the small cart. The prop, and other factors do just that.

 

[humber]

So what?

Well, chance. The wind changes enough to let the cart exploit the wind, yet pass casual inspection if NALSA are told that getting there does not matter.

Then, a few seconds where instrument error exceeds the margin, may work in favour. That depends on selling the bogus idea that acceleration proves steady state, or anything at all. There is no unique connection between acceleration and ddw. The cart is often not even close to ddw, but accelerates then too, and is worst close to the wind.
The wind changes direction often, and by more than 40degrees, and gusts to at least 18mph. Not even close.

 

[Jack by the hedge]

Well, chance. The wind changes enough to let the cart exploit the wind, yet pass casual inspection if NALSA are told that getting there does not matter.

Then, a few seconds where instrument error exceeds the margin, may work in favour. That depends on selling the bogus idea that acceleration proves steady state, or anything at all. There is no unique connection between acceleration and ddw. The cart is often not even close to ddw, but accelerates then too, and is worst close to the wind.
The wind changes direction often, and by more than 40degrees, and gusts to at least 18mph. Not even close.

Or - some guys who are trying to run their downwind cart have to try several times before there's a sufficiently steady wind to make the cart work and be accepted within the rules.

I like my version. Yours looks like sour grapes and clutching at straws.

 

[Michael C]

This boils the issue down nicely as to how that 72 kg mass of air, moving at 7 m/s (in the example we were examining) is able to impart kinetic energy to the 295 kg massive cart, moving at 9 m/s?

Once more you're comparing two values that have different units: 72 kg of air per second with 295 kg of cart. Making numerical comparisons between quantities with different units is nonsensical.

 

[windgrins]

PPG-2 Issues

Right. I'm sorry I didn't get back to you sooner on your question about that. That equation for propeller thrust is just F =ma, where the delta-v is the acceleration, and all the other terms give you the mass of the air being accelerated. Now that you have confirmed delta-v to be 2.2 m/s, you can calculate the air mass as ~ 72 kg.
This boils the issue down nicely as to how that 72 kg mass of air, moving at 7 m/s (in the example we were examining) is able to impart kinetic energy to the 295 kg massive cart, moving at 9 m/s? The only way that can happen is by doing work, using a propeller for example, but to do that work you need to use energy. A small aircraft with an engine can burn some fuel, a source of energy, and that enables the propeller to do some work on the air and generate thrust. Where is the energy for the cart to use to do work on the air to generate thrust? Sometimes the carteers claim the energy comes from the "ground moving under the cart". Yeah sure! Just to head that one off at the pass, let's stay in the frame where the ground is stationary-it has no energy in that frame. The wind has less kinetic energy than the cart (at least the 72 kg we are concerned with) so we still need to do work on that wind. I have shown that using the cart's own kinetic energy will not achieve anything, as you lose more than you can gain, unless you want to claim over unity. So the ground is out, the cart's KE is out, what is left? Now the carteers say the wind itself will provide the energy needed for the propeller to do the work in order to get energy from the wind! That's a vicious circle, otherwise known as perpetual motion, and is nonsense.
The simple truth of the matter: the cart, like every other wind powered craft, cannot go DDWFTTW, and the NALSA data shows without a doubt that it did NOT do so.
What is confusing people is the treadmill, which is said to be exactly the same as a cart on a road going DDWFTTW. In reality, the treadmill is an example of one piece of rotary machinery driving another piece of rotary machinery and all the energy is coming from the electric motor. It has nothing at all to do with wind power. Once you stop being fooled by the treadmill, and do a little math, and examine the NALSA data with an eye on the truth, you will find that Humber is the one who has this right and the carteers are not just wrong, but maliciously wrong.
All I ask you to do, all I ask anyone to do, is examine the facts and don't give in to the pack pressure that if you don't "get it" somehow you are an idiot.

Profpangloss,

I have zero investment in the argument other than a little time spent reading the posts and watching the videos. You seem almost like a sensible guy but are very heavily invested in your opinion. If you look back over my posts, I made a couple of minor incorrect statements that I was wrong about and the other posters pointed out the error and I publicly acknowledged my error. I don't mind education.

You have made two fundamental errors and here is where yours are:

The treadmill: A treadmill in still air with the belt running from right to left and a cart moving from left to right in place wrt the frame of the TM is equivalent of a cart moving on the ground at the speed the treadmill is running. This is obvious. If in the case of a tailwind blowing on the cart over the ground at the speed of the TM, the cart experiences no relative wind because it is at WS. In the case of a cart on the treadmill that is still wrt to the TM frame, the still air is a wind blowing over the moving belt from left to right wrt to the belt. The cart which is at WS in this frame is moving in a tailwind at WS and thus feels no wind. The transformation has all the same force vectors, speeds and all other items the same as a cart running over the earth with a tailwind equal to beltspeed. If one ignores nonsense issues like Coriolis force, relativistic frame dragging, magnetic changes, (which are all minute for this situation) the TM is an exact transform for the situation. You can't illustrate a difference because there aren't any.

If you have difficulty understanding this situation here is an easy way:
Imagine a cart with no prop tied to a string to the frame of the treadmill and the treadmill operating with a belt speed of 10mph. There is a fan at the front of the belt blowing steady air along the belt at 10mph. The cart has a headwind of 10mph and is traveling on the belt at 10mph. (note that the air is moving at the speed of the belt.) This is the same as a cart on the ground in no wind traveling at 10mph in still air. Now reduce the fan so that the air is 1mph slower. This is equivalent to a 1mph tailwind on the cart. The cart is rolling at 10mph on the belt into a 9mph headwind. Repeat the slowing of the fan 1mph. For every 1mph decrease in fan speed, the cart has 1mph less headwind which is equivalent to 1mph faster tailwind for a cart on the ground. When the fan is turned off the cart has no headwind and is equivalent to a tailwind of 10mph. This is our current situation. This isn't a difficult concept.

Your second error is a failure to understand:

The cart receives energy from the wind in the form of a push on the blades of the cart in an axial direction. This push is due to the props spinning and producing a net thrust from the relative wind. This is all standard aerodynamic lift/drag theory for wings in airflow. Yes, it takes torque to overcome the drag of the prop in the plane of the prop but there is a net gain here just like a sailboat sail has a net gain. The remainder of the system is just a way to translate this input energy to torque to continue the process. The wheels, reacting against the ground (or TM belt), are simply a method to convert some of this push to the torque that turns the prop. The remainder is used to either accelerate the cart below steady state and to overcome losses. At steady state, the force is all used to overcome losses. The torque is not the source of the axial push from the prop, the relative wind (wrt prop blades) is the source. No over unity, no PM. The feedback loop makes the machine work but is not a source of energy so get over this complaint. Nobody believes it, is so its a red herring to claim it. As stated, the airmass moving wrt to the ground is the energy source and the mechanism of the cart is just a method to harvest it. COE is not violated because the airmass is slowed wrt ground by the mechanism (losing KE of the airmass) and the cart ultimately expends this energy either accelerating or overcoming frictional losses (mechanical or aerodynamic). Specifically, you can't quite seem to visualize the transfer point of energy at the blade.

This is as simple as I can explain it. The only question left is:

Is the machine efficient enough to allow this transfer of energy to drive the cart over windspeed considering all losses. multiple carts by multiple independent observers say yes since they have a cart that does. A cart that is poorly designed or built may not be able to achieve this.

Your desire to question this is reasonable. Your reticence to accept the evidence is indicative of a personal issue not related to the mechanism of the cart.

Regards,

WindGrins

 

[ThinAirDesigns]

I have shown that using the cart's own kinetic energy will not achieve anything, as you lose more than you can gain, unless you want to claim over unity.

I don't think you've shown that. See the post of mine that I referred to above.

The cart doesn't use it's own kinetic energy to accelerate, so whatever Harold has shown in this regard is not relevant.

JB

PS: and the post you refer to is spot on, though again not related to the cart using it's own KE to accelerate.

 

[Dr. Keith]

Personally, I don't see the point of arguing with humber about this (or anything). I guess there's a small entertainment value, but what will be far more entertaining are the two possible outcomes:
- He'll never send a report to NALSA despite all his bold claims.
- If he does, we can then watch the hilarity ensue when NALSA tells him to go pound sand. And we'll get more than a few giggles out of the report when I post it here for all to see.

In fact, I don't think he'll send a report for that reason alone. As soon as he did, he could no longer control it in any way. We would all get to see what he thinks passes as physics and logic. I just don't believe that's a risk he's prepared to take.

I agree. Hummer has consistently thrown up nonsensical parts of objections but because of the forum format has never had to lay out his entire argument in a coherent way. His objections fight with each other and the data at every turn and laying them out end to end has never been required before.

I'd like to give him a chance to do so without interruption and see what comes of it.

Until then I will attempt the impossible dream. I'll likely fail, but goals are important.

 

[spork]

Once more you're comparing two values that have different units: 72 kg of air per second with 295 kg of cart. Making numerical comparisons between quantities with different units is nonsensical.

As humber would point out, you're just too "literal minded". There's no reason you can add torque, turtles, and red to prove the treadmill is a sham and the cart is a fraud.

Entertaining that humber's greatest insult is to call someone "literal" - isn't it? As an engineer, I take it as a compliment. Although to be fair, being insulted by humber should probably always be taken as a compliment.

 

[spork]

Hummer has consistently thrown up nonsensical parts of objections but because of the forum format has never had to lay out his entire argument in a coherent way...
I'd like to give him a chance to do so without interruption and see what comes of it.

He's had plenty of opportunity to do so, but is rarely willing to make even a single clear statement. When he does make a clear statement, he invariably finds he has to use the "fooled you" gambit since he's always wrong, and can never admit to being wrong.

Nothing will come of it. He won't lay out a consistent and comprehensive argument here or in a report to NALSA.

But he remains here for our entertainment.

 

[Llyricist]

For the hell of it, I put an engine on my crappy cart and took it up to 9 m/s in a 7 m/s tailwind. Running the engine through the same crappy transmission, I found I needed about 283 W from the engine to give me the same 11.4 N acceleration force.

And I found that the air lost 464 J /s of KE, about 456 Less than the wind powered version. Not exactly the same, but strikingly close to the 483 W engine power I had before.

 

[profpangloss]

No problem. But I wonder if you could comment on this post of mine as well.

OK. In that post you wrote: “I don't believe 9 m/s is the right speed to use here. That's the cart's speed relative to the ground. But the propeller exerts a force on the air, not on the ground. Since the propeller's thrust is moving the propeller through the air at only 2 m/s, only (160 N)(2 m/s) = 320 Watts of power is required.”

If the objective here was to move 72 kg per second of air @ 2.2 m/s, as a fan would, then 320 Watts would definitely be sufficient for that task. But the main objective here is to move the 295 kg cart @ 9 m/s over the ground. To do that requires Work = Force x Distance and in this case that is 160 N x 9 m = 1,440 Joules, or in terms of Power 1,440 J/s (Watts).

That's ok too, of course. We can pick any frame of reference to work in, and we should get the same answer.

OK so as to avoid even the possibility of ground power, I would prefer to stay in the FOR where the ground is stationary and has no energy.

I don't see why this is true. Why are the relative amounts of kinetic energy at all relevant? See this post by Michael C for a simple counterexample.

Michael wrote: "we have a large truck with the brakes off. We give it a push to set it rolling at, say 5 m/s. We throw a tennis ball in the direction of travel, at, say 10 m/s. The tennis ball hits the rear of the truck. We have now increased the kinetic energy of the truck by hitting it with something that has less kinetic energy."

True, but this does not contradict me at all. I said that an object with less kinetic energy can transfer that energy to another object with greater kinetic energy if work is done. Work was done in throwing the tennis ball at the back of the truck. This is also a bad example because it does not reflect the situation we have with the wind moving slower than the cart. If Michael wanted to better simulate that situation, he would have started the truck rolling at 5 m/s then lobbed tennis balls at it at 3 m/s. In fact, let the truck roll through a sea of tennis balls moving at 3 m/s and show how they can transfer any kinetic energy to the truck. I think you will find the truck must cut a path through that sea of tennis balls, pushing them out of its way. The truck will be losing kinetic energy to the tennis balls until it reaches some equilibrium speed either at the same speed the tennis balls are moving, or something even less. There is no way the truck will continue moving at 5 m/s.

It is true that the air is moving slower than the cart, and therefore, the propeller needs to be spinning in order for it to receive energy from the moving air. Some energy is required to spin the propeller, but I see no reason why the amount of energy it subsequently gains from the air can't be more than the energy required to spin it.

This is known as over unity. In Newtonian mechanics, there is no way to use energy such that it creates more energy than what you started with. If there was, we would never need to worry about an energy shortage. There are some weird processes in QM where it is possible to do this, but we don’t need to go there.

I don't think you've shown that. See the post of mine that I referred to above.

I think I have already answered that (also above) but let me know if you would like to discuss it some more.

You can say "the energy is coming from the electric motor", but that doesn't explain in any detail why the electric motor drives the cart forward rather than backward. After all, the tread of the treadmill is moving backward. Why doesn't the cart simply follow the tread backward?

I believe that as you analyze the cart on the treadmill more and more carefully, it will start to seem more and more like the same cart on the ground in a wind. All the relative motions are the same. All the torques and forces are the same. So, why would the cart not behave in the same way?

I assure you I have examined the treadmill in great detail. At first, I was as confused by it as anyone else, but fortunately I do have some experience with mechanical and electrical resonance as well as vibration analysis. That, and the fact that a velocity transform in no way implies any change to the physical system, enabled me to figure out what is happening on the treadmill, and that it has nothing at all to do with wind energy.

You say all the forces and relative motions are the same. Are you very sure about that? Here on the surface of the earth, everything moves along with that surface, even as the earth is spinning very rapidly on its axis. We move along with it because of our inertia, as well as the effect of the gravitational force on us and friction with the surface. If you jump in the air, you continue moving with the surface, it doesn’t move under you, because you cannot escape from the inertia and the earth’s gravitational force on you.

On a treadmill, once you start to move backwards with the tread, you also have inertia and if you jump up the tread does not move under you either, so it seems the same as the surface of the earth, but it isn’t! What if you don’t start the treadmill, but jump in the air and then switch the treadmill on while you are in the air? In that case, the tread will move under you. Now, instead of landing full on the tread, just very quickly and lightly bounce up and down. If you do it right, you can hold your position relative to the ground, while the tread moves under you. If you have a treadmill, try it! I will bet you any amount of money you cannot bounce straight up and down on any level road that is on the surface of the earth, and get it to move under you! (without any external force, such as wind force)So there must be something different! That something is simply not allowing the inertia of the treadmill to have an effect on you, by never allowing yourself to be dragged back with it in the first place.

Why do you think the cart must be held in place while the tread runs under it, to get it started? Two reasons, both equally important 1) to prevent the tread from building up any inertia in the cart 2) to get the wheels spinning and the propeller thrust going so the cart will no longer need to be held by hand. Now you have a cart in what is called a latched state, running on the treadmill with no inertia from the tread. It will slide and bounce around in a way that you will never see a cart on any road do. The treadmill is NOTHING like a cart on a road! Just forget about it unless you want to make little toys to amuse the kiddies.

Once you throw away the so-called treadmill equivalency, and you examine the NALSA data carefully, you will find there is NOTHING to support the claim of DDWFTTW, certainly no mathematics! It is a farce and it is time it was totally exposed as such.

 

[69dodge]

The cart doesn't use it's own kinetic energy to accelerate, so whatever Harold has shown in this regard is not relevant.

No, I wouldn't say that the cart uses its own kinetic energy to accelerate. Not directly, anyway. But I think it might not be entirely incorrect to say that some of the cart's kinetic energy is (or, perhaps, would be) used up in turning the propeller. ("Would be", because once the propeller is turning, it allows the cart to gain more energy from the wind than is expended in turning it.) Of course, everything happens simultaneously, so the cart's kinetic energy doesn't ever actually decrease, but the tendency is there. Does that make sense?

 

[spork]

OK. In that post you wrote: “I don't believe 9 m/s is the right speed to use here. That's the cart's speed relative to the ground. But the propeller exerts a force on the air, not on the ground. Since the propeller's thrust is moving the propeller through the air at only 2 m/s, only (160 N)(2 m/s) = 320 Watts of power is required.”

If the objective here was to move 72 kg per second of air @ 2.2 m/s, as a fan would, then 320 Watts would definitely be sufficient for that task. But the main objective here is to move the 295 kg cart @ 9 m/s over the ground. To do that requires Work = Force x Distance and in this case that is 160 N x 9 m = 1,440 Joules, or in terms of Power 1,440 J/s (Watts).

OK so as to avoid even the possibility of ground power, I would prefer to stay in the FOR where the ground is stationary and has no energy.

Michael wrote: "we have a large truck with the brakes off. We give it a push to set it rolling at, say 5 m/s. We throw a tennis ball in the direction of travel, at, say 10 m/s. The tennis ball hits the rear of the truck. We have now increased the kinetic energy of the truck by hitting it with something that has less kinetic energy."

True, but this does not contradict me at all. I said that an object with less kinetic energy can transfer that energy to another object with greater kinetic energy if work is done. Work was done in throwing the tennis ball at the back of the truck. This is also a bad example because it does not reflect the situation we have with the wind moving slower than the cart. If Michael wanted to better simulate that situation, he would have started the truck rolling at 5 m/s then lobbed tennis balls at it at 3 m/s. In fact, let the truck roll through a sea of tennis balls moving at 3 m/s and show how they can transfer any kinetic energy to the truck. I think you will find the truck must cut a path through that sea of tennis balls, pushing them out of its way. The truck will be losing kinetic energy to the tennis balls until it reaches some equilibrium speed either at the same speed the tennis balls are moving, or something even less. There is no way the truck will continue moving at 5 m/s.

This is known as over unity. In Newtonian mechanics, there is no way to use energy such that it creates more energy than what you started with. If there was, we would never need to worry about an energy shortage. There are some weird processes in QM where it is possible to do this, but we don’t need to go there.

I think I have already answered that (also above) but let me know if you would like to discuss it some more.

I assure you I have examined the treadmill in great detail. At first, I was as confused by it as anyone else, but fortunately I do have some experience with mechanical and electrical resonance as well as vibration analysis. That, and the fact that a velocity transform in no way implies any change to the physical system, enabled me to figure out what is happening on the treadmill, and that it has nothing at all to do with wind energy.

You say all the forces and relative motions are the same. Are you very sure about that? Here on the surface of the earth, everything moves along with that surface, even as the earth is spinning very rapidly on its axis. We move along with it because of our inertia, as well as the effect of the gravitational force on us and friction with the surface. If you jump in the air, you continue moving with the surface, it doesn’t move under you, because you cannot escape from the inertia and the earth’s gravitational force on you.

On a treadmill, once you start to move backwards with the tread, you also have inertia and if you jump up the tread does not move under you either, so it seems the same as the surface of the earth, but it isn’t! What if you don’t start the treadmill, but jump in the air and then switch the treadmill on while you are in the air? In that case, the tread will move under you. Now, instead of landing full on the tread, just very quickly and lightly bounce up and down. If you do it right, you can hold your position relative to the ground, while the tread moves under you. If you have a treadmill, try it! I will bet you any amount of money you cannot bounce straight up and down on any level road that is on the surface of the earth, and get it to move under you! So there must be something different! That something is simply not allowing the inertia of the treadmill to have an effect on you, by never allowing yourself to be dragged back with it in the first place.

Why do you think the cart must be held in place while the tread runs under it, to get it started? Two reasons, both equally important 1) to prevent the tread from building up any inertia in the cart 2) to get the wheels spinning and the propeller thrust going so the cart will no longer need to be held by hand. Now you have a cart in what is called a latched state, running on the treadmill with no inertia from the tread. It will slide and bounce around in a way that you will never see a cart on any road do. The treadmill is NOTHING like a cart on a road! Just forget about it unless you want to make little toys to amuse the kiddies.

Once you throw away the so-called treadmill equivalency, and you examine the NALSA data carefully, you will find there is NOTHING to support the claim of DDWFTTW, certainly no mathematics! It is a farce and it is time it was totally exposed as such.

Wow, that's all very interesting. I wonder why it's so critically important for harold/yev/ppg to refuse to respond to SZ's questions?