Split Thread The validity of classical physics (split from: DWFTTW)

[Belz...]

I'm so lost, here. Can anybody fill me in, seriously, or must I either give up or read 92 pages ?

 

[mender]

Start with the first few pages of this thread:

http://www.internationalskeptics.com/forums/showthread.php?t=128483

You'll see humber jump in and test the depth of the water with both feet. Most of the 3200 posts on that one and the 3600 posts on this one are devoted to answering humber mumbles.

Has anyone thought of publishing these two threads? The market would be small but some of the material is priceless. Just look at the humberisms in the signatures!

 

[Subduction Zone]

Basically this started pretty much as a result of humber not understanding the idea of frame of reference equivalence. Since then he has been making one physics blunder after another along with more and more outrageous explanations and claims. Some of his claims are on the order of "a boat moving the speed of a current in a river will still have a bow wave".

 

[mender]

Thank you, humber, for taking time out from your very busy heckling schedule to respond. Let's have a look and see how you did on your summary, shall we?

(1) You agree that only a powered vehicle can make progress up the belt.
(2) The cart is a powered vehicle, that moves by power to the wheels. List the power source and draw the power flow for (a) a cart in the wind and (b) a cart on a belt
(3) It is not in principle possible for a belt to drive the wheels ( as in the unpowered car on the belt) unless the cart is between two masses, one acting on the wheels and one acting on the propeller, and having a relative velocity between those two masses.
(4) The power for the cart comes from the belt and is used to push against the air around the cart. Where does the power for the cart come from when it is outside?
(5) Connect the dots to (3) This should be saved until you correctly understand what is actually happening in #2, #3, and #4
(6) The cart is spinning its propellor and wheels, but not moving wrt to the air around it when it is at the same speed as the air around it.
(7) The spinning is due to the introduction of a third force (the air mass) that serves to keeps it in place on what little energy it can get from the belt if the energy is only enough to do so. If more energy is applied to the cart by increasing the relative speed difference between the two masses that the cart is transfering energy between, the cart moves forward wrt the air around it and either moves up the belt on the treadmill (see many videos) or moves faster than the wind when outside (see Jack Goodman's video). For the data gathered by testing the Goodman cart with a treadmill, see the article published (link provided if needed)

Please note the corrections and do some research on those items pertaining to your misconceptions (you are wasting a lot of valuable time with your excursions). You'll never progress unless you acknowledge your mistakes and take the time to understand why you are wrong.

 

[CNY_Dave]

OK, think about this, humber:

I have a little car. It has elliptical wheels. It's sitting on the floor, at its lowest possible position (the contact point with the floor is at the end of the minor axis of each ellipse). I have a little motor connected to the axle, that will turn the axle. As it does so, and the wheels begin to rotate, the contact point of each wheel will move in front of its axle, due to the geometry of an ellipse.

I'm interested only in moving as far as a quarter-turn of the axle will take me. During that time, the contact patch of every wheel will be ahead of the axle. Can this car move?

Heck with ellipses:

http://www.macalester.edu/mathcs/SquareWheelBike.html

Dave

 

[Furcifer]

For example your claim about reference frames. I already tried to explain that, you can look it up.

And I clearly stated that using the cart as a reference frame was ridiculous. No one specied a co-ordinate system. That helps when picking an inertial refernce frame doesn't it? That's what I am familiar with. I've never in my life had someone say "Oh, you don't know inertial refernece frames blah blah blah" If I've made a mistake along the way, why not correct it? "No, not the cart wrt to the earth, the belt wrt the earth"

Give examples of opposites? Water is compressible (everything is actually compressible) but the change in density is usually so small so we can ignore it in many calculations. Air is compressible but the change in air density that happens in low speed aerodynamics is so small so the density change can be ignored in that application.

You agreed it was nitpicking, and I see humber nitpicked your nitpick. I'm, just saying this acomplishes nothing. In fact, it confuses things even further.

Take a look in any good aerodynamics book and you are going to find a lot about incompressible flows.

Yes. You will also find that most propeller thrust calculations that treat air as incompressible deal with speeds below Mach 1. That's fine, but I have made the claim that due to the tailwind and the extremely low speeds (compared to an airplane prop at cruising speed) this isn't necessarily a correct assumption. If I found reference to this would you agree?

A propeller works because it speeds up some air and thus change the momentum of the air.
edit: I looked at some of your older posts. It would make a huge difference if you started to use the momentum in your explanations instead of the talk about change of mass which not make much sense, definitely is badly defined and not true by using some standard definitions. The change of mass times the velocity make sense for a rocket (because the you use up the mass of the fuel) but it doesn't make sense for propeller where new mass is entering the system the whole time and the mass in is equal to mass out at steady state (and we get a thrust force at steady state obviously).

Thank you for reading the posts.

Yes, a propeller works by accelerating some mass of air. A rocket works by accelerating some of its own mass. A cart does not lose some of its mass as it moves up the cart. I never said that, that would be dumb.

 

[jjcote]

Heck with ellipses:
http://www.macalester.edu/mathcs/SquareWheelBike.html
Dave

Hey, my buddy Stan's square-wheeled bike! (Although I don't know why everybody keeps calling it a bicycle, since it's a tricycle.)

But yeah, the reason why I didn't cite that is because I have no idea whether humber is going try to come back with the idea that "ahead" and "behind" are measured relative to a line from the axle drawn perpendicular to the surface, and that gets complicated when you're dealing with a surface consisting of a series of cycloids. The elliptical wheel question tidily eliminates the issue of how you decide what's "ahead" and what's "behind".

Not that it matters, because even for a round wheel on a flat level surface, what humber is saying is rubbish.

And not that it has any relevance at all to the issue of whether operation on a treadmill is the same as operation on a road, anyway. Particularly since humber has absolutely no information about what the contact patch of spork's cart is doing, other than his bizarre assertions.

 

[jjcote]

Yes. You will also find that most propeller thrust calculations that treat air as incompressible deal with speeds below Mach 1. That's fine, but I have made the claim that due to the tailwind and the extremely low speeds (compared to an airplane prop at cruising speed) this isn't necessarily a correct assumption. If I found reference to this would you agree?

I'm not sure I understand. Are you suggesting that some part of the DDWFTTW could have an airspeed that is not waaaaay less than Mach 1?

 

[Michael C]

And I clearly stated that using the cart as a reference frame was ridiculous. No one specied a co-ordinate system. That helps when picking an inertial refernce frame doesn't it? That's what I am familiar with. I've never in my life had someone say "Oh, you don't know inertial refernece frames blah blah blah" If I've made a mistake along the way, why not correct it? "No, not the cart wrt to the earth, the belt wrt the earth"

Of course the cart is not "a reference frame", but it can define one, or a set of them. It's a handy shorthand to talk about the "frame of reference of the cart": as long as people are clear about what reference frames are, there is no problem in doing this: the "frame of reference of the cart" defines any reference frame in which the cart remains stationary. For analysing the DDWFTTW cart, there are three sets of reference frames that are useful:
- The set of frames where the cart is stationary.
- The set of frames where the road is stationary.
- The set of frames where the air is stationary.

 

[Furcifer]

I'm not sure I understand. Are you suggesting that some part of the DDWFTTW could have an airspeed that is not waaaaay less than Mach 1?

No. I was saying that perhaps treating the air as incompressible at standard atmospheric pressure and temperature and the relatively slow speed of the cart isn't the best way to do it.

 

[spork]

"one bit must move faster than another bit" is the way I spoon-fed it it to Spork.

Thank you. I prefer to digest your insanity in small bites.

I sure wish you had the lucidity to be able to bet me on this ridiculous notion that the contact patch must be behind the axle in a forward moving car. If you're willing to bet, you can go ahead and name the amount. But I will not get into a 100 page pissing match about how to orchestrate the bet. If you say yes, we're both giving the money to a 3rd party.

 

[Furcifer]

Of course the cart is not "a reference frame", but it can define one, or a set of them. It's a handy shorthand to talk about the "frame of reference of the cart": as long as people are clear about what reference frames are, there is no problem in doing this: the "frame of reference of the cart" defines any reference frame in which the cart remains stationary. For analysing the DDWFTTW cart, there are three sets of reference frames that are useful:
- The set of frames where the cart is stationary.
- The set of frames where the road is stationary.
- The set of frames where the air is stationary.

I know, but this started as a result of my saying there was no video of the cart starting from rest on the treadmill. Then "inertial reference frames" came in. That's why I said the cart accelerating up the treamill is not a good "inertial" reference frame.

AFAIK There's no law that defines what you chose as a reference frame, just laws that govern them. If you want you can pick the cart moving up the treadmill. I guess you'd need accelerometers all over the cart to do this. That and patience with the math.

 

[spork]

Hey, my buddy Stan's square-wheeled bike!

And a video:
http://www.youtube.com/watch?v=LgbWu8zJubo

I was saying that perhaps treating the air as incompressible at standard atmospheric pressure and temperature and the relatively slow speed of the cart isn't the best way to do it.

Completely ludicrous, but admittedly not at all surprising coming from you.

 

[Furcifer]

Completely ludicrous, but admittedly not at all surprising coming from you.

2 Things that facsinate spork 1. Propeller driven carts 2. Bicycle pumps

"Tables fulla hi-hat, a dash of drums
Sprinkle in a little keyboard, a pint of rum
With just a pinch of purple haze and a gallon of bass
Mix snares with rock 'n' roll and throw it all in ya face"

That's Ludacris.

Care to share why you think that's ludicrous? A reason, data, a link to something to support you claim? Anything?



edit: Never mind, I found out for myself. It was ludicrous. My bad. My apologies spork.

 

[humber]

OK, think about this, humber:

I have a little car. It has elliptical wheels. It's sitting on the floor, at its lowest possible position (the contact point with the floor is at the end of the minor axis of each ellipse). I have a little motor connected to the axle, that will turn the axle. As it does so, and the wheels begin to rotate, the contact point of each wheel will move in front of its axle, due to the geometry of an ellipse.

I think that to even begin to thin about this canard, whether I should ask how the cart on the treadmill may deal with square wheels. Given that I said to John, that wheels need not be round, it seems odd to offer such an underwhelming example.
Completely wrong analogy, as usual.
In this case, the axle moves up and down as the wheel rotates. The motor's energy is transferred to gravitational potential energy and the then released and so forth. There are many other devices that use a fulcrum ahead of the axle, but none of them are wheels like on the cart.

I'm interested only in moving as far as a quarter-turn of the axle will take me. During that time, the contact patch of every wheel will be ahead of the axle. Can this car move?

 

[semper]

You are a glutton for punishment. The KE that you;
(1) Lost when running up the belt
(2) Avoided gaining by simply arriving at "beltspeed".

As you can see, there is no KE in the runner when stationary w.r.t the ground.
This is true of the cart. The model is built upon false premises.

You disappoint me Mr Crumbler. I suppose in your KE equation, there is never a requirement for subscript on the velocity term to indicate what it is referred to. Why then, do they insist on providing subscript functionality?

What if you were correct? How many other engineering principles and working devices would you have to declare impossible? And Mr Humber, why are you not making a fortune from your devices? A small inexpensive mechanism for determining the gravity vector, not subject to the motion of itself or drift, would make you a squillionaire I would think. Meanwhile all the commercial and military aircraft are having to make do with the best INS money can by and conventional physics can design. It is very selfish of you not to make your invention public.

 

[humber]

Basically this started pretty much as a result of humber not understanding the idea of frame of reference equivalence. Since then he has been making one physics blunder after another along with more and more outrageous explanations and claims. Some of his claims are on the order of "a boat moving the speed of a current in a river will still have a bow wave".

More that you can't accept that the treadmill is not an equivalent to the real world item.
You have not denied me one of the many claims that you say are physics blunders.

 

[mender]

You have not denied me one of the many claims that you say are physics blunders.

Now why would we want to deny you one of your obvious pleasures, that of making as many physics blunders as you can? Go ahead, have fun!

 

[spork]

I think that to even begin to thin about this canard, whether I should ask how the cart on the treadmill may deal with square wheels. Given that I said to John, that wheels need not be round, it seems odd to offer such an underwhelming example.
Completely wrong analogy, as usual....

I've noticed you never seem to care for examples that prove you wrong. By the way, he didn't offer an "analogy". He gave you a specific example (one of many) where you're just flat wrong.

You have not denied me one of the many claims that you say are physics blunders.

Every claim of yours that could possibly be parsed (a small percentage to be sure) has been cleanly and fully disproven as rubbish.

 

[humber]

Thank you, humber, for taking time out from your very busy heckling schedule to respond. Let's have a look and see how you did on your summary, shall we?

(1) You agree that only a powered vehicle can make progress up the belt.
(2) The cart is a powered vehicle, that moves by power to the wheels. List the power source and draw the power flow for (a) a cart in the wind and (b) a cart on a belt

Done a long time ago, and more than once, and much more.

(3) It is not in principle possible for a belt to drive the wheels ( as in the unpowered car on the belt) unless the cart is between two masses, one acting on the wheels and one acting on the propeller, and having a relative velocity between those two masses.

No, it is only necessary for that force to be equal to the frictional losses induced by the belt and internal mechanism. The cart does not move, so there is little work done.

(4) The power for the cart comes from the belt and is used to push against the air around the cart.
Where does the power for the cart come from when it is outside?

It needs only a small amount of power, and that comes from the belt, but in the real world, from the propeller. They may not be casually transposed.
The propeller cannot drive the wheel at angular velocity greater than that of the belt, because that is fixed by the wheels and gears, so it is simple not possible for the cart to move by means gained from the belt.

(5) Connect the dots to (3) This should be saved until you correctly understand what is actually happening in #2, #3, and #4

So you say.

(6) The cart is spinning its propellor and wheels, but not moving wrt to the air around it when it is at the same speed as the air around it.

Also the case for still air. Only the name has been changed to "windspeed".
The air local to the cart at windspeed, will not be that of a still room. That is simply unrealistic. As I have shown in my series of "balloon tests", the treadmill wind is not like real wind at all.

(7) The spinning is due to the introduction of a third force (the air mass) that serves to keeps it in place on what little energy it can get from the belt if the energy is only enough to do so. If more energy is applied to the cart by increasing the relative speed difference between the two masses that the cart is transfering energy between, the cart moves forward wrt the air around it and either moves up the belt on the treadmill (see many videos) or moves faster than the wind when outside (see Jack Goodman's video). For the data gathered by testing the Goodman cart with a treadmill, see the article published (link provided if needed)

Good luck to it, but it can't do that on the belt. The propellor simply cannot drive the wheel at an angular velocity such that the wheel rim moves faster than the belt. They are synchronised.
However, if there is some momentum available, then it can drift a little by creating some differential slip. I think it does a number of actions dependent on belt conditions and so forth. It's just a the result of the wheel and belt speeds not quite opposing each other.
Goodman's machine works using momentum.

Please note the corrections and do some research on those items pertaining to your misconceptions (you are wasting a lot of valuable time with your excursions). You'll never progress unless you acknowledge your mistakes and take the time to understand why you are wrong.

No, my argument sticks.