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

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Well, that's exactly the business JB and I are in. Unfortunately we're not instant millionaires. :(

Then you must have left out an important correction factor. How about the lighter gravity at higher elevations such as on top of a treadmill?

For a treadmill hight of 15 cm, I get a gravatational difference of about 4.7
e-8 g (maybe I should also include the hight of the chalk mark).
 
Just a sidenote for humber who is fascinated by the action of rolling oranges in his warehouse job.
You don't like honest work?

It does not take much of a slope for a ball to keep rolling in one place on a conveyor belt.
Correct.

A dip that is not easily perceivable to the naked eye would do. If the rolling resistance of the ball (or orange) was the same as the component of the force of gravity parallel to the belt then the ball could roll endlessly in one spot.
Ut pendet continuum flexile, sic stabit contiguum rigidum inversum (the cart)
Robert Hookes.
There was no dip. I told you that, but it makes no difference. They are quite common. It does it, that is enough. There are a wide range of objects that will do the same.

The rolling resistance of a ball is very small and would be a constant at the speed that a conveyor belt is typically run at.
Yes, low friction is the key.

Notice the lame attempt he had in trying to answer the hobo question? Basically his answer is "if I cheat I can figure it out".
The answer to the next brain-bender will be 10m/s. When will you understand. I have been ahead of you, all the way.

humber, I don't think spacediver will mind if I refine the question a bit more, you we will assume are the hobo.
I may!

You are nude, no GPS, no super handy pocket gyroscope, nothing.
Anesthetized, too?

You are in the aforementioned boxcar. There are various boxes and balls and other nontechnological items lying about. The evil scientist announces on a loud speaker that you have 10 minutes to find the "front" of the car, or else the car will be filled with poisonous gas. How would you do it? Earlier you said it could be done easily so ten minutes should be plenty of time. I will start to time you at the beginning of your next post.

Don't get in the boxcar in the first instance.

When will you understand, SZ? You are playing a parlour game.

You are playing "Einstein in a lift" AND taking away his accelerometer, because you do not seem to understand what the original experiment "says".
 
I suggested both mechanisms (conveyor belt slightly uphill or slight low spot in conveyor belt) for the oranges stuck on the conveyor belt way back in the original thread. I suggested that the weight of the oranges might cause a slight sag in the belt. Humber responded with something about how grapes could climb up a ramp, and the only mechanism he suggested for the phenomenon was "low resistance", which is certainly an important part of the picture, but not the whole story.

You were what is known as "wrong"

I really think that Humber, fascinated by the phenomenon of oranges staying in one place on the belt, concocted some bizarrely wrong hypothesis to account for it, possibly involving some sort of mystical coupling with "the ground" and "force balance" and when he saw the propeller cart on the treadmill concluded that the same thing was happening with the cart.

Oranges on a belt, like ducks in a row.
 
The question is moot. For humber to have a navel suggests an umbilical cord, which further suggests he's the offspring of a mammal. I'm not quite sure what he is - but I find that notion fairly unlikely.

"Moot", another one of mine.
 
HUMBER...

These questions are intended seriously. They are being asked so that we can gain a better understanding of your interpretation of physics, and so that you can gain a better understanding of ours, so I'd appreciate if you'd answer them.

Often, it's hard for us to distinguish between your serious and sarcastic answers, so I'm sure that many of us fail to understand exactly what you're trying to say in many cases.


Are you suggesting that if this experiment were actually performed, that the person jumping could do so to the height of the caboose, (and even hit it) and then land exactly in the same spot on the floor?


Assuming the force he applies in jumping is exactly vertical, then yes, we are.
If you believe otherwise, can you tell us why you think so?


If the person jumps within the caboose full of air, then KE will be lost due to the vertical component alone. But what you are telling me is not right. What stops the body from being displaced? The air? The usual friction to the floor being optional? Not at all necessary?
I could go on. Is the displacement such that the air can be considered adiabatic?


Can you explain in more detail why KE would be lost when he jumps? And how would this be different from what would happen if the train wasn't moving?

Are you saying that that the person's horizontal velocity will change when he is no longer connected to the floor of the box-car?

Note: The air in the box car is travelling at the same speed as the train, and the train is travelling at a constant velocity with no accelleration.


The treadmill has no useful connection with windspeed travel.


Given two situations, where a cart begins at windspeed and released, please explain to me exactly how the forces involved differ...

Situation A: Cart on the road with the wind blowing East.
Relative to the cart, the air is still and the ground (road) is moving West.

Situation B: Cart on a treadmill in an enclosed room.
Relative to the cart, the air is still and the ground (belt) is moving West.

I honestly don't see any difference between these two situations.


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Back to the older questions...

You still haven't answered the question about why you don't think a balloon travelling at windspeed would continue to travel at windspeed.

But the balloon isn't passing through the air, it's moving with the air. It's completely stationary relative to the air. If the baloon isn't passing through the air, then it's not getting any drag of any kind from the air. Why then yould the balloon be dragged in the direction the ground is moving relative to the air?


And of course, could you answer the skateboarder question for me sometime?


Who can argue with logic like that? I can't, because I have no idea what you're trying to say. So, instead of trying to explain my understanding to you, I'm going to ask you to explain your understanding to me.

Let's go back to the car and skateboarder example for this.

We'll assume that in both situations the car's velocity is unaffected by the impact. (The moving car's engine is capable of instantly compensating for a sudden change in load, and the parked car has a very good hand-brake.)

Let's say the skateboarder weighs 100 pounds, the car weighs 2000 pounds, and the collision is non-elastic.

Using the formula for kinetic energy; E = (M/2)(V^2), it looks to me like...

The kinetic energy imparted to a stationary skateboarder weighing 100 pounds from a car moving at 60 mph would be: E=(100/2)(60^2)

The kinetic energy imparted from a stationary car to a skateboarder moving at 60 mph, and weighing 100 pounds would be: E=(100/2)(60^2)

Clearly, if you're right about the two situations being different, the outcomes should be different; but no matter how hard I look, I just can't find a difference.

So please, explain to me where this difference is, show me how I can apply the formulas to find out what the difference should be myself, and tell me exactly how much kinetic energy is really imparted from the car to the skateboarder in each case.
 
When will you understand, SZ? You are playing a parlour game.

You are playing "Einstein in a lift" AND taking away his accelerometer, because you do not seem to understand what the original experiment "says".


Have your accelerometer if you want. It reads 9.8m/s/s. The train has a constant velocity, so the reading never changes.

ETA: Just so you understand, the accelerometer would also read 9.8m/s/s even if the train wasn't moving.
 
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"Moot", another one of mine.

Please note that humber now has ownership of "hover", "slipping", "denied", and "moot". Any use of these (or any other) words will constitute proof that humber is correct in every way.



HUMBER...
These questions are intended seriously. They are being asked so that we can gain a better understanding of your interpretation of physics, and so that you can gain a better understanding of ours, so I'd appreciate if you'd answer them.

You have to be kidding!?

I assure you humber won't and can't answer your questions. Nor does he have any position consistent enough to examine.
 
Have your accelerometer if you want. It reads 9.8m/s/s. The train has a constant velocity, so the reading does not change.

No, Brian_M. You are not seeing the wood for the trees. When Einstein did these experiments, he was working up an argument.
He put himself in a lift, so cutting off all external information. His conclusion was that when this was done, there would be no means of determining the velocity, but he noted that the one thing he could not shut out, was acceleration. Absolute acceleration has a "meaning" that absolute velocity does not.

The experiment is designed not to say "you can't tell", that is ludicrous. The point of a scientific tool is to reveal, not to obscure. He is simply stripping away all the other things, to reveal the "bottom line".

When all my objections to the boxcar are removed, when everything including the accelerometer is removed, then you cannot tell. Useful, don't you think?

Why? To support the same "useless" situation that happens at windspeed on the treadmill.
 
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Please note that humber now has ownership of "hover", "slipping", "denied", and "moot". Any use of these (or any other) words will constitute proof that humber is correct in every way.

I rule.
 
when everything including the accelerometer is removed,

What about if you HAVE the accelerometer?

You see, we too are trying to get to the "Bottom line".
 
Yes, I changed my mind. You should try it.

So, instead of just saying "Oops, didn't want to say that" you falsely declare it as double post. Tells a lot about you. Covering your tracks, i would say.

And why should i change my mind? To enter your teletubby land? No thanks, i prefer reality, as most others do in this thread except you. If i really would feel to enter that fantasy land of yours one day, which i highly doubt, i'd better go with drugs. Way more fun, and i can be sure that it is all over the next day.
 
Yes, I changed my mind. You should try it.

There are some custom modifications to this forum site. Because this forum deals with heated arguments, the edit function has been modified to preserve the history of all edits. Have you noticed that the little message under the post that says it's been edited is underlined as if it were a link?
 
HUMBER...
These questions are intended seriously. They are being asked so that we can gain a better understanding of your interpretation of physics, and so that you can gain a better understanding of ours, so I'd appreciate if you'd answer them.
Yes, I know. I am not trying to "avoid the answer" but to show what extremes you must go to, to get the result that you already expect.

There is nothing to understand in that way, that you seem to suggest Brian_M. You are "right".
What good can such an environment be? You can do nothing!. How could it be the basis of a useful idea? This is a pointless discussion in many ways, because the treadmill has nothing to do with frames at all. It should be just a game, to see if you can beat the objections, but in this case, one side simply removes all means until the only possible outcome is that you have nothing left. That would simply be time to got to bed, not the basis of a means of scientific inquiry. They are hypothetical ideas, that have been made real in the most literal of ways, to say that the treadmill could be a frame of reference.

Often, it's hard for us to distinguish between your serious and sarcastic answers, so I'm sure that many of us fail to understand exactly what you're trying to say in many cases.
Assuming the force he applies in jumping is exactly vertical, then yes, we are.
If you believe otherwise, can you tell us why you think so?
Can you explain in more detail why KE would be lost when he jumps? And how would this be different from what would happen if the train wasn't moving?
Detailed answers are never sarcasm. Sometimes, I do wonder what there is left to say. The treadmill is false, it is so. I am not interested in playing parlour games as a sideline. They are trivial. The solution is in any book on the topic. So what?
[/QUOTE]

Are you saying that that the person's horizontal velocity will change when he is no longer connected to the floor of the box-car?
Note: The air in the box car is traveling at the same speed as the train, and the train is traveling at a constant velocity with no acceleration.

Perhaps I am saying WTF does a hobo in a van have to do with anything?
You know, I have conceded this point before.
But I ask, what do you expect to happen? That's the odd thing. To say "Ah hah, this proves that you can't tell" rather begs the question at to who would think otherwise.
To make a case for whatever "ideas" come from this bizarre isolation ward, you first need to instill the idea the somehow "most people/science" would say the contrary, so you can "fix it" by calling upon faux relativity.

This "proof" is then used to support the treadmills notions; and they are notions, so that anything that is relative is "the same" in someway. You can't tell the real wind from "treadmill wind". In this case you can, but may be you could make a system where the effects were similar, and so would be a good model. The treadmill is full of exemptions to its own rules, to the point where "windspeed" means nothing.

The real road is connected to the ground, so the belt must also be the ground. The earth moving below the cart.
Stand on the treadmill belt so as to move with it. Take a rock from your pocket and throw it on the belt. Just like for the real road, it lands at your feet.
Now, take another rock so that it lands on the floor. Where is that?
Windspeed, of course. Take a bus and do the same. Windspeed bus.
(No, it is not a 'boundary condition', if it were that would be for the belt, not the air). Treadmill primary rule:- "All things that are not going back with the belt are at windspeed[/U]". There are no intermediary states.

The belt is not the ground or earth, its the equivalent of a real moving road, set in the ground. That's where the rocks go. (Or the air is the ground..) When you realise that, the cart is going nowhere at all, figuratively or literally. It's an orange on a belt or the item slipping on the belt at the supermarket checkout.

Given two situations, where a cart begins at windspeed and released, please explain to me exactly how the forces involved differ...

Situation A: Cart on the road with the wind blowing East.
Relative to the cart, the air is still and the ground (road) is moving West.

Situation B: Cart on a treadmill in an enclosed room.
Relative to the cart, the air is still and the ground (belt) is moving West.

I honestly don't see any difference between these two situations.

What you are trying to say is that a person standing in moving wind, is the same as a person moving in still air?
That's a metaphysical and terminological nightmare. Never ask an expert
"What's the time?"

No, the question is, can you make something that emulates the first situation, so that you can do the work in the comfort of indoors?
The treadmill, should it work, is a test platform, not a "frame"
If you look at Drela's cart proposal, there are two drawings. That is the correct use of "relative velocites". It's convenient to look at it that way, that's all. You can't take that idea, and make it real in the sense of the treadmill.

--------------------------------------------------------------

You still haven't answered the question about why you don't think a balloon travelling at windspeed would continue to travel at windspeed.
A drawing for that.

And of course, could you answer the skateboarder question for me sometime?
OK
 
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There are some custom modifications to this forum site. Because this forum deals with heated arguments, the edit function has been modified to preserve the history of all edits. Have you noticed that the little message under the post that says it's been edited is underlined as if it were a link?

I changed my mind, including at to whether I would add that note.
 
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