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Galilean relativity, or is there such thing as absolute motion?


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1 hour ago, billvon said:

Nope.  No power is available if the belt is moving the same speed as the wind.  The only time power is available is if there is a difference in the two, and (the important part) that difference in speed is harnessed to produce power.  Take away either and the cart just sits there.

Apparently you did not read my post where I said this:

 The only part of the belt that matters to the cart is where the wheels touch the belt, and where the wheels touch the belt, the belt is formed into small arcs which are in circular motion, same  as the wheels are in circular motion. There is no inertial reference frame where this circular motion stops, as evidenced by the wheels are turning in all inertial frames. Simply put, those little arcs of belt are in circular motion and are driving the wheels in all inertial frames. There is no inertial frame, even the one where the top surface of the belt is at rest, where the belt is not driving the wheels. The belt is always driving the wheels and the treadmill cart has nothing to do with wind or wind energy.

The belt is always providing energy to the cart by turning the wheels in all inertial frames because the wheels are turning in all inertial frames (as long as the treadmill is running)

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1 hour ago, OceanBreeze said:

Don't keep telling me what a GT is. I know damn well what it is and how and why it is used. 

You don't seem to understand that there is NEVER any relative tailwind for the cart because it is held on the belt and started in still air.

The only wind the cart ever sees is a relative headwind when it starts to advance.

You say you can place the cart at the front of the belt and it will go back with the belt and it will self start? I call bullshit on this. I have looked to find evidence of this and all I found were people making excuses about why this does not work, such as "the belt is not long enough". So I would like you to back up this claim and show me a video of the cart self-starting in this scenario. I predict the cart will fall off the back of the belt! The only way these carts can start on the treadmill is to be held down on the belt until the prop winds up enough to produce thrust, then it is released.

Whether or not the cart can self-start on a (sufficiently long) treadmill is irrelevant to the claim of whether it can travel ddw faster than the wind steady-state.  Self-starting (i.e. starting at rest with respect to the ground/treadmill belt) is a different and transient regime compared to ddw and how the cart behaves under those different conditions depends on its design. 

Starting a treadmill cart at rest with respect to the air is Galilean equivalent to towing an outdoor cart up to windspeed and then releasing it.  If the cart accelerates downwind from that initial condition and maintains faster than wind speed (as both the treadmill carts and the Blackbird can do) that proves the claim. 

So for the main point at issue there's no reason to consider self-starting.  With that said, here are two videos.  One shows a cart self-starting on a circular treadmill.  At around 2:15 the other video shows a cart on a regular treadmill where the cart is pushed back and then accelerates up the belt.  While it is moving back it is experiencing a tailwind (falsifying your assertion that this never happens).

 

1 hour ago, OceanBreeze said:

When you say the cart is going faster than the wind, you are in effect saying it is outrunning an imaginary tailwind. It is exactly the same as a small wind up toy car running on the floor. It too is running faster than an imaginary wind.

This shows that you really do not understand GTs, or maybe wind, or maybe both.  There is no relevant difference between the tailwind on a treadmill compared one outside or over an ocean or lake.  The air is moving relative to the treadmill surface - that is wind, full stop.

Edited by truthseeker
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1 hour ago, OceanBreeze said:

You don't seem to understand that there is NEVER any relative tailwind for the cart because it is held on the belt and started in still air.

This is not true. Here is a video of it starting itself without being held onto the surface. At the 3:20 mark. And the condition at that moment, is a relative tailwind. https://www.youtube.com/watch?v=LABSbSTIEvM&t=2s

Second, you continue to confuse two things: the motion of air relative to the surface, and motion of air relative to the vehicle. Truthseeker told you that the source of the energy is the air vs. surface motion, but you keep quoting that and replying about air vs. vehicle. Both him and me tried to steer you back to the correct topic at least twice each. The conversation would go easier if we all keep the concepts straight and be careful what we're replying to. To quote myself:

It [both the treadmill, and natural outdoor wind] produces the relative motion between the air and the surface (i.e, the "wind"). (He said this in the post you were quoting: "Wind is the RELATIVE motion of air with respect to a surface (the belt in this case).") The relative motion between the air and the vehicle can be positive, zero, or negative, and the vehicle can accelerate (as evidenced in the videos) in all 3 of those conditions as long as the wind (air vs surface) is present.

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The only wind the cart ever sees is a relative headwind when it starts to advance.

It sees a relative tailwind on the vehicle while going slower than the wind, zero relative wind while going the same speed as the wind, and a relative headwind while advancing (i.e. going faster than the wind). During all 3 of these conditions, the (I hate to use this term, but it's the standard in sailing) "true" wind (i.e., air vs. surface) is a tailwind.

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You say you can place the cart at the front of the belt and it will go back with the belt and it will self start? I call bullshit on this. I have looked to find evidence of this and all I found were people making excuses about why this does not work, such as "the belt is not long enough". So I would like you to back up this claim and show me a video of the cart self-starting in this scenario. I predict the cart will fall off the back of the belt! The only way these carts can start on the treadmill is to be held down on the belt until the prop winds up enough to produce thrust, then it is released.

https://www.youtube.com/watch?v=LABSbSTIEvM (same link as above, 3:20 mark)

https://www.youtube.com/watch?v=-O3ZqklSndM (1:40 mark) 

https://www.youtube.com/watch?v=2JL_7cx7lnc (from the beginning) and 

https://www.youtube.com/watch?v=QTF5kw51H60 (from the beginning)

https://www.youtube.com/watch?v=GC-EoGbdyzE (wind tunnel, ground is stationary and air is moving)

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When you say the cart is going faster than the wind, you are in effect saying it is outrunning an imaginary tailwind. It is exactly the same as a small wind up toy car running on the floor. It too is running faster than an imaginary wind.

As far as the kinematics of the cart, sure they're the same. They're both going faster than the air. But their energy source is different. In one case it's a wind-up spring, in the other it's the wind (air vs surface). Evidence: the moment you remove the wind (air vs surface), the cart stops. As long as the wind (air vs surface) continues, the cart continues.

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The only part of the belt that matters to the cart is where the wheels touch the belt, and where the wheels touch the belt, the belt is formed into small arcs which are in circular motion, same  as the wheels are in circular motion. There is no inertial reference frame where this circular motion stops, as evidenced by the wheels are turning in all inertial frames. Simply put, those little arcs of belt are in circular motion and are driving the wheels in all inertial frames. There is no inertial frame, even the one where the top surface of the belt is at rest, where the belt is not driving the wheels. 

All of this is true, (except that depending on the combination of materials the tire can deform the same as, or even more than, the road surface; and increase the contact patch area) but what does this have to do with being on a treadmill vs not?

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The belt is always driving the wheels and the treadmill cart has nothing to do with wind or wind energy.

Except that as as long as the wind (air vs surface) continues the cart continues, and when the wind (air vs surface) stops the cart stops. If it isn't for the wind (air vs surface), then what powers the motion?

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The belt is always providing energy to the cart by turning the wheels in all inertial frames because the wheels are turning in all inertial frames (as long as the treadmill is running)

If the belt by itself is always the power source, then the power should continue to flow to the cart if the air in the room is evacuated, or if the prop is removed. Would it?

Edited by EfisCompMon
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19 hours ago, truthseeker said:

Whether or not the cart can self-start on a (sufficiently long) treadmill is irrelevant to the claim of whether it can travel ddw faster than the wind steady-state.  Self-starting (i.e. starting at rest with respect to the ground/treadmill belt) is a different and transient regime compared to ddw and how the cart behaves under those different conditions depends on its design. 

You are the one who brought it up! You claimed you can set down the cart on the front of the treadmill and it will go back with the belt and self-start.

When I called bullshit on this, you now are backing away from that claim, saying it is irrelevant. If it is irrelevant, why did you make the claim?

 

 

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This shows that you really do not understand GTs, or maybe wind, or maybe both.  There is no relevant difference between the tailwind on a treadmill compared one outside or over an ocean or lake.  The air is moving relative to the treadmill surface - that is wind, full stop.

I am really getting tired of you telling me what I don't understand when it is you who is making the crackpot claim, not me. And you still do not understand what I said. There is never any wind energy or wind force on the cart that is held down and started on the treadmill. And this is true no matter what frame of reference you use as forces are not frame dependent. You can't seem to wrap your head around that. It is only the belt at the wheels that provides any force and energy to the cart and that is true in any and all reference frames also.

Since no tailwind ever reacts with the treadmill cart and cannot be detected by an observer on the cart, it may as well be imaginary or non-existent. 

By the way, I have no interest at all in the non-inertial rotating tables. They have no place in a thread about Galilean relativity.

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Let's make this very simple. 

Suppose I take a treadmill cart and put it in a very long wind tunnel.  The floor of the tunnel is a treadmill belt, but the treadmill's motor is off.  The wind tunnel fans are on and create a steady wind at 10 mph.  I attach the cart to a moving arm that holds it and runs it down the tunnel at 10 mph (at rest with respect to the air) for a few seconds and then releases it.  

Question - will that cart accelerate to a steady-state speed faster than 10mph?

Edited by truthseeker
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19 hours ago, EfisCompMon said:

 

If the belt by itself is always the power source, then the power should continue to flow to the cart if the air in the room is evacuated, or if the prop is removed. Would it?

Don't be silly. The cart is designed to turn a propeller and create thrust in the air in order to move. That does not mean the air or the prop is the energy source. In fact, they are the energy sink. The belt is the only source of energy for the cart and this is true regardless of reference frame.

It is probably possible to design a cart that does not require a prop or air to run up the belt. One possible way is to add another set of wheels that run on the treadmill frame. Or maybe use a vibrational system, such as vibrating conveyors use. Some vibrating conveyors are designed to work in a vacuum, to transport medical pills without contamination. Those pills are moving faster than the wind too.

I still remember a football game I had as a child where you turned it on and the players vibrated all around the board. They were all going faster than the wind!

As I said several times, you are jumping to a conclusion about the treadmill cart that is not based on any scientific investigation, it only supports your other claim about the outdoor cart.

What needs to be done is a thorough scientific analysis, probably by an independent lab, of exactly how the cart is able to advance up the belt. I suspect it is not because of uniform linear motion but rather some combination of circular motion at the belt/wheel interface, followed by a loss of traction and sliding a bit before regaining just enough traction to take enough energy from the belt for the cart to continue moving. But I don't have the test equipment to test this myself, so you can put it down as guesswork. But it makes more sense to me than what you people are claiming. At least it is an alternative explanation and you can't dismiss it out of hand just because it does not support your narrative.

 

 

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4 minutes ago, truthseeker said:
4 minutes ago, truthseeker said:

Let's make this very simple. 

Suppose I take a treadmill cart and put it in a very long wind tunnel.  The floor of the tunnel is a treadmill belt, but the treadmill's motor is off.  The wind tunnel fans are on and create a steady wind at 10 mph.  I attach the cart to a moving arm that holds it and runs it down the tunnel at 10 mph for a few seconds and then releases it.  

Question - will that cart accelerate to a steady-state speed faster than 10mph?

Question - will that cart accelerate to a steady-state speed faster than 10mph?

It will gradually slow down until it reaches a constant velocity equal to the amount of kinetic energy that the wind is giving it, such that Ewind = 1/2 Mcart Vcart^2

Edited by Vmedvil2
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4 minutes ago, Vmedvil2 said:

Okay, so what is the TL:DR on this thread? I didn't feel like reading it however I assume it is someone cranking it up?

It has already reached the TL:DR point for me.  I have a lot of important work to do to get ready for the upcoming expeditions and can't be wasting my time on this nonsense.

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1 minute ago, Vmedvil2 said:

It will gradually slow down until it reaches a constant velocity equal to the amount of kinetic energy that the wind is giving it.

It will slow down until it reaches equilibrium with the wind force and the resistance forces (rolling resistance being the chief resistance force).

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3 minutes ago, OceanBreeze said:

It will slow down until it reaches equilibrium with the wind force and the resistance forces (rolling resistance being the chief resistance force).

oh ya, I didn't think about friction, ya friction would need to be included too you are right. Ewind - Efriction1/2 Mcart Vcart^2

Edited by Vmedvil2
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On 1/27/2022 at 9:55 AM, OceanBreeze said:

Don't be silly. The cart is designed to turn a propeller and create thrust in the air in order to move. That does not mean the air or the prop is the energy source.

Actually it partially does mean that. The relative motion between the air and the surface is the energy source, and if you remove either one, it will no longer go. They are both equally necessary and important.

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The belt is the only source of energy for the cart and this is true regardless of reference frame.

On the runs on the desert where the ground is stationary and the air moves, your sentence becomes "The ground is the only source of energy for the cart and this is true regardless of reference frame." Does this really seem true to you?

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It is probably possible to design a cart that does not require a prop or air to run up the belt. One possible way is to add another set of wheels that run on the treadmill frame.

You mean like this? https://www.youtube.com/watch?v=k-trDF8Yldc Yeah. The air is removed and another object/medium is substituted for it, which must have motion relative to the ground, to power the vehicle. Remove the ruler or the table, and it does not go. Just the same as the propcarts. What you seem to be saying here is that the air (or other object/medium) that moves relative to the surface, IS actually necessary?

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But I don't have the test equipment to test this myself, so you can put it down as guesswork. But it makes more sense to me than what you people are claiming. At least it is an alternative explanation and you can't dismiss it out of hand just because it does not support your narrative.

I won't dismiss it out of hand, I'll look at anything you put in front of me. But what's wrong with the current theory that's in front of us, that makes perfect sense, and is consistent with dozens of experiments put on video (and some certified by the official body of land sailing)? Linear, circular, ground moves, ground stationary... every permutation is there. At this point the only reasonable thing to do is to apply Occam's Razor and go with what's simple, present, and holds together, and there's no reason I see to favor some other as-yet-to-be-stated theory over it. Is there one?

Edited by EfisCompMon
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9 minutes ago, Vmedvil2 said:

oh ya, I didn't think about friction, ya friction would need to be included too you are right. Ewind - Efriction1/2 Mcart Vcart^2

Damn, I am already getting rusty i forgot about the treadmill, final equation  Ewind + ETreadmill - Efriction  = 1/2 Mcart Vcart^2

Edited by Vmedvil2
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43 minutes ago, OceanBreeze said:

You are the one who brought it up! You claimed you can set down the cart on the front of the treadmill and it will go back with the belt and self-start.

When I called bullshit on this, you now are backing away from that claim, saying it is irrelevant. If it is irrelevant, why did you make the claim?

The question is, is it possible to go DDWFTTW, and if you see a cart that's going DDWFTTW regardless of whether it was hand-started or self-started, it is presently going DDWFTTW and thereby answers the question in the affirmative.

Anyway, you're casting way the circular treadmill evidence, what about the video he showed you on a linear treadmill of the cart getting pushed to a speed slower than the wind, and then still accelerating through and above wind speed?

And what about the linear runs over the desert where it self-started and then accelerated through and above wind speed?

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By the way, I have no interest at all in the non-inertial rotating tables. They have no place in a thread about Galilean relativity.

 

The forward-aft axis is inertial. Are you saying that a force 90 degrees to the rolling motion, and the thrust/drag direction, is powering the cart somehow? 

Edited by EfisCompMon
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13 minutes ago, Autodidactocrat said:

Not to complain or sound like a whiney ***** but, you'll what's what if you take a step

 

13 minutes ago, Autodidactocrat said:

Sir you need to calm down, harming pussycats is bad Mkay.

Edited by Vmedvil2
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