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

[Clive]

If you're fixed to a rotating surface then you are constantly accelerating (in a circle).

I agree if you're using an inertial frame of reference, but you might not be. I chose not to, by having my frame of reference rotate with my surface. Not sure if you saw my later post on this? In a NON-INERTIAL reference frame, my velocity could still be zero even though I was on a rotating surface (and in that case Newton's Laws wouldn't hold).

If you are accelerating, then you do not have a fixed (unchanging) velocity.

Yep!

Anything which is not undergoing acceleration can be used to measure velocity against (and consequently, used as a frame of reference).

... "and consequently used as an inertial reference frame" is more complete in my opinion. Maybe I am just being pedantic here - my original response to Greg was because I thought the way he described what was sufficient to define an inertial frame of reference was lacking.

If I'm floating through space (hopefully in a space-suit) I can use myself as a reference, and accurately determine that my velocity is precicely zero, as measured from my own frame of reference.

Yes, if you are in free-fall in space, then that is close enough to an inertial frame of reference (even though you are almost certainly still accelerating due to various gravitational influences). "Close enough" because in a relatively small region of space around you, you can ignore the very slightly different acceleration experienced by other objects. On a larger scale though, you'd expect gravitation forces from those far off masses to be in somewhat difference directions, etc.

 

[RossFW]

In a NON-INERTIAL reference

There's no such thing, Clive.

The POINT of a reference is to be able to make statements about your motion in relation to other objects, and thus determine your RELATIVE motion to them. You can't do that if you are accelerating at the time, which you are if you are following a curved path. Your velocity wrt any unaccelerated object will be constantly changing (which is what acceleration IS).

 

[mender]

For anyone solving my little math problem, the rolling resistance is assumed to be constant and independent of the speed of the cart. Thanks to Clive for letting me know that I should have included that in the statement of the problem. He also mentioned my mixing of units and somewhat unclear way of presenting the problem but hey, I are a meckanik!

 

[Clive]

There's no such thing, Clive.

Read this and weep Ross:
http://en.wikipedia.org/wiki/Frame_of_reference#Non-inertial_frames
QED

ETA: For your "Reference":
Frame of reference
Inertial frame of reference
Non-inertial frame of reference
Rotating frame of reference

 

[RossFW]

Fair enough, Clive, but you might notice that Fictitious forces have to be added to a non-inertial frame in order for observations from that frame to make sense.

It's not a term I'd heard before, so I certainly stand corrected (Note to Humber, this is what "Admitting Error looks like!!), but it would seem they are not as useful a tool as are inertial frames.

I suppose if you happen to be in curved motion (as we are on the earths surface) you need to build mathematical tools to counter that and make sense of observations made from there.

Interesting concept, I'll do some reading (ANOTHER note to Humber- this is known as LEARNING. You can tell when you don't need to learn any more- it's characterized by a lack of pulse and respiration!!)

 

[Clive]

Fair enough, Clive, but you might notice that Fictitious forces have to be added to a non-inertial frame in order for observations from that frame to make sense.

Yep - you are right, and the need to add those fictitious forces one way we can tell we are not in an inertial frame of reference. I think it's true to say (in a very strict and pedantic sense at least) that there are no frames of reference in the "real universe" that are truly inertial, at least with respect to Newtonian mechanics. All we can ever hope for with Newtonian mechanics is to get something that is "approximately inertial". This might not be a problem with General Relativity, but perhaps I just need to go and read those Wikipedia pages yet again.

 

[Clive]

... but hey, I are a meckanik!

... and I are often too pedantik!

 

[RossFW]

Well, if you are Pedantic (the overwhelming desire to correct people when they are wrong), it's still better than being Humdantic (The overwhelming desire to correct people when they are RIGHT!!)

 

[semper]

This thread has developed into an exploration of Humber's perception of the validity of classical physics, and no matter how much he writes, no-one can get any more understanding of his theories.
It would help If he would respond to particular questions. I'd love to know if he finds his methods work in practice, for him. That is, if he has a practical problem involving physical objects in the conventional physical world, involving other people outside (who could validate that they experience the same world), can he work out and predict the outcome of events. It seems to most of us that it would be very dangerous to get involved, since the force and mass interactions could affect our bodies, limbs etc.
Are there some basic experiments we could agree on which involve the use of our bodies rather than only external objects like carts etc, which would give us real motivation to be correct? Would Humber survive, could we tell?
I'd like him to predict this one and explain why. If two cars accelerate toward eachother then maintain a constant velocity, then launch off a ramp into the air, and collide mid air, will they get damaged before hitting the ground? Would Humber try this?

 

[humber]

Oh, I've known about cavitation for a very long time. I, too, am waiting with bated breath to find out the nature of the bubbles in the air. What do you suppose is in them? Plasma? Vacuum? Soap? Straw men?

You mean you have heard someone say it. Your irony shows little potential to understand. Any further information concerning cavitation, would not be of use to you.

(Also, nobody seems to have pursued it, but I have been curious about humber's assertion that the contact patch has to move behind the axle in order for a wheel to move, and that this is a difference between the cart on the treadmill and the cart on the road. I have no idea why he is saying this, and it seems like the implications...

Now two more things to add to the list of what you don't know about.
(1) You said you do not understand the paddle
(2) Now you show ignorance of the fundamental mechanics of a car.

...could reveal still more interesting things about the humberverse.)

But nothing interesting about you.

 

[humber]

You may think that you've done it (dreams are free after all), but you actually haven't. In my opinion, you haven't convinced anybody of anything that supports your long-running fantasy that "'treadmill wind' is not like real wind", in any way at all. But in the interests of keeping the record straight, is this list above still current and complete from your perspective?

1, Paddle wheel. (No)
2. The opposing motion of wheel and belt, with no axle movement.(No)
3. The relationship between friction and wind force. (No)

The no's are your failure to refute them. Want to try again, Clive?
I need the laugh.

 

[RossFW]

You mean you have heard someone say it. Your irony shows little potential to understand. Any further information concerning cavitation, would not be of use to you.

Read:- I'm not going to talk about Cavitation any more because it will reveal I used a word without knowing what it meant.

C'mon, Humber! Finding out how Cavitation can occur in a gas would be ENOURMOUSLY useful to us all!!

I would be as earth-shattering, Nobel Prize winningly important as explaining how a mass can have zero KE in ALL frames af reference.

ETA- You also don't know the meaning of the word "Irony"

 

[humber]

You mean by reducing pressure, you can't turn gas into ... gas?

JB

Yes, if you wikki that, you will see that. I knew you would, in the same way I knew John would wikki "over-energy" before posting. He always does that.

Anyway, it happens in gaseous systems. The effect of a visible bubble in liquids is due to surface energy, and not simply lower pressure.
A very similar mechanism occurs in pneumatic systems. They make popping sounds, just like bubbles, but not so literally as you seem to think.

 

[Christian Klippel]

You mean you have heard someone say it. Your irony shows little potential to understand. Any further information concerning cavitation, would not be of use to you.

Translation: I just project my stupidity on you. Since i now nothing about physics at all, how can you think that i know what cavitation is? I just use fancy-looking words to impress people who might be even dumber than myself. Dare you don't ask my about what they mean, or in what context they should be used, because i really, really have no idea at all.

Now two more things to add to the list of what you don't know about.
(1) You said you do not understand the paddle
(2) Now you show ignorance of the fundamental mechanics of a car.

Translation: Let me project some more of my trollish stupidity on you. You ignore my garblegook because you want to stick to real physics. But that doesn't work in my teletubby-land. Unless you get as stupid as me, you will never understand my nonsense.

But nothing interesting about you.

Translation: I have absolutely no clue about real physics, so your facts are of no interest to me. Since you obviously know more than i do, that makes you uninteresting to me.

 

[humber]

Don't forget "impedance".

Adiabatic is a standard term. It is quite often used in the design of loudspeaker systems.

The wikki link confirms that mechanical impedance is correct.


Next. No wonder you believe a magical carts. This latest remark has the same tone of medieval ignorance you so often display.

 

[humber]

Negative drag?

Err....you mean "Thrust"??

No.

 

[RossFW]

Yes, if you wikki that, you will see that. I knew you would, in the same way I knew John would wikki "over-energy" before posting. He always does that.

Anyway, it happens in gaseous systems. The effect of a visible bubble in liquids is due to surface energy, and not simply lower pressure.
A very similar mechanism occurs in pneumatic systems. They make popping sounds, just like bubbles, but not so literally as you seem to think.

ONE citation that this is called cavitation please?

 

[humber]

And "inert", as in:

and again....

inert /I"n<schwa>:t/ a. & n.M17. [L inert-, iners unskilled, inactive, f. as IN-3 + art-, ars skill, ART n.1]A adj.

1 Of matter or a material thing: having no inherent power of action, motion, or resistance; inanimate; having the property of inertia.
M17.b Without active chemical or physiological properties; unreactive. E19.2 Of a person, an animal, etc.: inactive, slow; not inclined for or capable of action or movement; motionless. L18.1 F. BOWEN If matter is essentially inert, every change in it must be produced by the mind.2 R. P. WARREN He lay beneath the high carved headboard of his bed, inert as a log.A. BROOKNER With their curiously inert attitude to life, I doubt that they would even notice my absence.Special collocations: inert gas (a) a (relatively) unreactive gas; (b) spec. = noble gas s.v. NOBLE a. (usu. in pl.).B n. An inert or unreactive substance. M20.inertly adv. M18.inertness n. M17.

I bet you are one of Drela's proudest achievments.

 

[RossFW]

No.

We'll add "Drag" and "Thrust" to the "Doesn't understand" pile then!!

 

[sol invictus]

Check the math: find dr/dt for [t,1].

I know what you're saying, but I don't think humber knows what a hyperbola is, let alone that it would be the distance in this case. But it probably is true that many humberisms arise from failing to understand the difference between scalars and vectors.

humber, I notice you stopped responding to our little discussion. Do you still think the relative velocity and/or KE between two passing cars moving at constant velocities goes to zero at some point, or have you understood your mistake?