• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Down wind faster than the wind

humber said:
And what makes you think that it is not 'm' that is zero? Why not?
Click to expand...

Because that would make no sense at all.

And this;
V1= 20m/s .Let's make that 0.
V1 = 0
Click to expand...

???

KE = (1/2)m(-20)2. If v=0, KE= real number +++
Click to expand...

????

It seems to me that if I pick up the cart from the treadmill and haul it back to my 'view'. It has no KE. So does it leave it behind? No, it's all relative, you say. If that's true, how come that is still hangs on to the KE stored in the propellor and wheels, but not the chassis?
Click to expand...

If the wheels/prop are spinning, they are spinning in all inertial frames, and so they always carry some KE. So?

I was using examples and notions used in this thread. Not my ideas.
Perhaps you can tell other posters why that is wrong.
Click to expand...

You were using them completely incorrectly. The other posters were right.

You performed the same subtraction at the top of your post.
Click to expand...

I showed how to compute the KE (due to linear motion) in a new frame. You did something else entirely - something completely nonsensical.
 
Humber, I think you can be a good friend with a Scottish paraglider pilot called Murray Hay.

You are both misunderstood physics geniuses.
 
Modified said:
That is the very definition of KE. It doesn't "change", it is a relative measurement. You are saying something analogous to "The speed cannot change just because of change of reference."
Click to expand...
I mean that KE is a property of the body. It does not change with perspective.

Do work by doing what? Taking KE measurements from a different frame will not affect the amount of KE that can be converted to another form of energy for any process. Try to come up with an example where it will. Keep in mind that all KE values must be measured from the same reference frame, you can't mix frames as you are fond of doing, or use objects that have a different velocity in the two frames (as you are fond of doing with the earth).
Click to expand...
If I convert the real cart's KE, I can carry it away in another form. The only time that there is cognate when on the belt, it is when the cart is moving back at that speed, otherwise the recoverable energy falls as the cart "moves" towards stationary. Also the KE when held in the operator's hand is zero ( I can choose a common datum) but when on the belt, it is essentially the same. That is not right. In your view, the cart would pickup KE relative to the belt yet no work is done. That may be OK by your view of equivlance, but it violates a great number of other precepts.
I can mix frames. Otherwise symmetry between frames would fail. That would mean Newton's laws fail.

But that is not the real point. The treadmill is not a frame of reference, so the actuality is otherwise. So I deny it on two counts
(1) "equivalence" is valid scientific precept, but misused to generate the treadmill.
(2) The treadmill does not even meet that bastardized version of equivalence.

I can stand on the belt, and test the KE, and find that it is wrong. It does not model the real world equivalent.

I have to say that this gets more bizarre as time moves on. I was being whimsical when suggesting that the treadmill observer was at widspeed, but it seems not enough. Are you suggesting that if leave the room, that I am no longer at windspeed? That the very existence of the belt, changes the entire world? How far away do I have to be?
The retraining bar is another. OK, I see the logic that says it could be a large mass at windspeed, but that must to relate to the real world, not another abstracted frame. The cart is said to "be the same as" a cart at windspeed.
 
humber said:
Still, name that academic that supports you.
Click to expand...


There are plenty. One that jumps to mind is an aero professor at Stanford. There is also every single person on this thread and almost every single person on 20 other threads I can provide the URL's for. There is still not one single person that will support your bizarre nonsense.


humber said:
You can't cover your traces. You gave a limp wristed response to my porch ideas. The usual simple denial, along with some canned remarks about frames of reference.
Click to expand...

I'm pretty sure that's just a simple lie. I don't think I responded in any way to your silly porch ideas. You have never challenged me in any way. I defy you to provide an example.

If you think that I have completed that argument, perhaps you would like to pick it up again. I've got several lines of attack behind the pawns.
Click to expand...

How scary to think you have more B.S. behind the original B.S.!


Again, please bring us one person that buys into your B.S. Feel free to find the guy that talks to himself at Arby's.
 
sol invictus said:
Because that would make no sense at all.
Click to expand...
Good answer. Making KE zero "makes no sense at all"

V is a vector, not zero.
Click to expand...

If the wheels/prop are spinning, they are spinning in all inertial frames, and so they always carry some KE. So?
Click to expand...
Because those 'frames' are a fiction. If the prop still shows its KE, and I can measure it, why does the cart not? Does it 'know', do you think?

You were using them completely incorrectly. The other posters were right.
Click to expand...
I did exactly what you did.

I showed how to compute the KE (due to linear motion) in a new frame. You did something else entirely - something completely nonsensical.
Click to expand...
[/QUOTE]
I did exactly what you did. It fails. If you must, assign velocities to them, then make them zero. Same paradoxical result.
Funny though. How can work backwards from that point?
No, sounds like 'pass the parcel' with KE.
KE is not transferable, any more than is a dimension.
 
spork said:
There are plenty. One that jumps to mind is an aero professor at Stanford. There is also every single person on this thread and almost every single person on 20 other threads I can provide the URL's for. There is still not one single person that will support your bizarre nonsense.
Click to expand...
That he agrees that the treadmill represents the cart at windspeed?
Names and URL of said academics. I will check them all, and contact them.

I'm pretty sure that's just a simple lie. I don't think I responded in any way to your silly porch ideas. You have never challenged me in any way. I defy you to provide an example.
Click to expand...
Yes, you did. Do your own errands if you want to find it.

How scary to think you have more B.S. behind the original B.S.!
Click to expand...
Witty. You still can't play though.

Again, please bring us one person that buys into your B.S. Feel free to find the guy that talks to himself at Arby's.
Click to expand...
No need. I have plenty. You need the support.
 
I'm now more or less certain that humber doesn't earn a living, and strongly suspect he's under the full time care of a professional.

Stop using personal attacks. Attack the argument, not the arguer
Replying to this modbox in thread will be off topic  Posted By: Gaspode
 
Last edited by a moderator:
humber said:
I mean that KE is a property of the body. It does not change with perspective.
Click to expand...

That is completely wrong. KE is a relative measurement. Again, please read an intro physics text.

Also the KE when held in the operator's hand is zero
Click to expand...
That is completely wrong. In the frame of the moving belt surface, the KE of the cart is the same before and after it is placed on the belt. You can not mix reference frames when comparing KE, just as you can not mix reference frames when comparing velocity.
 
What about the guy with a PhD working at Google that changed is mind? Humber did you forget him or are you simple a liar?
 
spork said:
I'm beginning to believe humber believes he's right. How scary is that!?

But in his world he's the only one that is right. He can't find a single other person in the humberverse to back up his completely looney assertions.
Click to expand...

Humber is right, the treadmill is nothing but a red herring.
 
Modified said:
That is completely wrong. KE is a relative measurement. Again, please read an intro physics text.
Click to expand...
Yes, but not physically. Momentum is not scalar, but a vector.
What do you think momentum is? It goes with the mass. Like the momentum of of the particles that make it. Masses warp space time. Why? Good question, no real answers yet, but it goes with the mass.

If you instantly stop a mass in an elastic collision, it will move move in the opposite direction, but with the same absolute KE. The cart is said to be "moving", but not wrt to the treadmill observer. However, when the cart travels back with the belt, all is in order. The cart's velocity is that of windspeed, but in the other direction. Then the KE is correct. It agrees (as it should) with both the belt and treadmill observer. Just like the elastic collision it represents.
When actually at windspeed, the cart should have KE, it has none. It is simple to demonstrate (from the belt) that this is the case.

If I simply assume that there are no frames involved, and what I am seeing is what it as appears to be, then I have no problem at all. All frames, or perspectives as the really are, are in complete accord. You will not be able contradict my stance. That is flat out. Any test, any time, it will pass, whereas the treadmill is a frame produces contradictions.


That is completely wrong. In the frame of the moving belt surface, the KE of the cart is the same before and after it is placed on the belt. You can not mix reference frames when comparing KE, just as you can not mix reference frames when comparing velocity.
Click to expand...

Yes, I can, otherwise you are suggesting non-locality. Newton's laws hold for all relative velocities likely to be experienced by the cart.
Also, it supports my claim. No KE from any view, when the cart is said to be windspeed. I need not mix frames, it fails from the belt.

What if I use the treadmill for its intended purpose? Standing on the static belt, I record all relative KE's and velocities. If I then start the belt, so to run in place, apart from the local changes in limb motion, nothing changes. Indeed, I have no KE becuase I am not moving.

If I raise myself by the side rails, then I am also much the same. No KE, no change to my previous readings. From this position, I can lower my feet to the belt, and do much as I please. 'Run', let my feet slide and so forth. No change. The only way there is a change is if use the belt as a reference, but even then, its influence seems to be by how well I am attached to it.
This is implausible. I can't see how a reliable relationship between so-called frames can be based upon this. It also forces me to accept the belt as an "absolute reference", before I can even begin measure it.
 
Last edited:
fredriks said:
What about the guy with a PhD working at Google that changed is mind? Humber did you forget him or are you simple a liar?
Click to expand...

I see, the path of redemption is the way to scientific veracity?
Nope. He has a PhD in computer science. He does not represent an academic institution. Not only that, his about-face is wrong. That was acknowledged in this thread. So, check before you squawk.
 
humber said:
The idea of relative kinetic energy, that is the literal interpretation of that idea, is silly. It's magic.
Click to expand...

http://en.wikipedia.org/wiki/Kinetic_energy
"Thus kinetic energy is a relative measure and no object can be said to have a unique kinetic energy."

http://en.wikipedia.org/wiki/Galilean_invariance
"Correspondingly the kinetic energy of an object, and even the change of the kinetic energy due to a change in velocity, depends on the inertial frame of reference."

http://elmuseet.net.dynamicweb.dk/Default.aspx?ID=618
"For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the earth."

http://www.physicsforums.com/archive/index.php/t-187425.html
"You can only talk about gaining or losing kinetic energy relative to a particular inertial frame, it's not an absolute concept."

http://en.allexperts.com/q/Physics-1358/Kinetic-enrgy-absolute-frame.htm
"The kinetic energy of a moving object is NOT absolute. It is, in fact, dependent on the speed of the observer relative to the object being measured."
 
You must log in or register to reply here.

Back
Top Bottom