Merged DDWFTTW in a “Real” Wind

[jduffy77]

Is it? See if you can find fault without contradicting yourself.

As I am sure you are quite aware, there is no way to find fault with gibberish, precisely because it is gibberish. Can you find fault with this statement:

The invalidation of the preliminary lorentz simulations is constrained by 7 ^ 2 / 4. We also can mark this transform as a result which approaches the maltese limit. I think that the basis for this is clear.

 

[humber]

As I am sure you are quite aware, there is no way to find fault with gibberish, precisely because it is gibberish. Can you find fault with this statement:

The invalidation of the preliminary lorentz simulations is constrained by 7 ^ 2 / 4. We also can mark this transform as a result which approaches the maltese limit. I think that the basis for this is clear.

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[jduffy77]

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[ThinAirDesigns]

It's funny how the laws of Humprofverse vary depending on if the ball is big or small.

JB

 

[humber]

It's funny how the laws of Humprofverse vary depending on if the ball is big or small.

JB

KE = 1/2 mv^2
p = mv

KE = 1/2 mv^2 =
1/2m (mv)^2 =
(p^2)/2m

 

[69dodge]

Conservation of momentum holds in the absence of external forces.

Perhaps the matter is as simple as this: profpangloss does not believe that the earth exerts a force on the cart.

profpangloss, can you comment?

In general, I have trouble figuring out how you think about force. You talk a lot about energy, but hardly at all about force. At the risk of putting words into your mouth, you seem to think that, since, in your preferred reference frame, no energy is transferred between the earth and the cart, then neither do they exert any force on each other.

Is that correct?

I mean, is that what you think?

(It isn't correct.)

 

[69dodge]

Initially the transfer of energy only causes local deformation, since the planet is not infinitely rigid, but the energy disperses through the planet.

There is negligible transfer of energy to/from the earth. (But the momentum transfer is not negligible.)

 

[humber]

There is negligible transfer of energy to/from the earth. (But the momentum transfer is not negligible.)

The tyre will dissipate some of the cart's energy to the ground as a result of the force applied via friction. That is an inevitable loss, and part of the compounded "rolling resistance". The lower, the better.
It is absurd to think that enough force can be applied to move the entire planet, without the ground yielding or the wheel spinning.

Arguments based on the mechanics of particles, do not apply to complex machines.

Carteers can have it the way they like. If they want to add the burden of spinning the Earth to the prop's work...knock yourself out.

 

[humber]

There is negligible transfer of energy to/from the earth. (But the momentum transfer is not negligible.)

In the case of a car, the engine (fuel) provides the energy for the car's KE.
The momentum moves from the ground, ( and initially with p = 0 wrt the ground) but increases to mv when transferred to the moving car.

The cart has no engine, so can't power momentum exchange from the ground to the cart. The exchange is from the wind to the cart, with the ground only gaining what is lost due to rolling on the surface.

 

[jadebox]

Moreover, since the car is accelerating, it is acting under the external force of the engine, this is not a closed system as fuel is being burned.

Wow.

--Roger

 

[humber]

Wow.

--Roger

Yes. That is all that is left for you to say.
The fuel is certainly not part of a closed system, unless you want to include all the energy used to make it.

 

[humber]

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Replying to this modbox in thread will be off topic  Posted By: LashL

 

[windgrins]

Tomorrow is another day!

Of course. There is no energy transfer to the Earth as a whole. For one thing, it's elastic. For a dropped brick to move the Earth, the other side of the planet would need to instantly move. The examples from Michael_C, are as always, taken from simplified cases for the general public consumption, and where objects are treated as points.

When large highways were built, many Carteers of the time gave dire warnings that traffic would change the Earth's spin, and wanted the flow to be alternated in compensation.

The only energy imparted to the ground is via local work of deformation of the soil, but again let them have the transfer.

Using the centres of mass as frames of references, the cart and Earth are both at rest.

From that frame, the cart moves, and gains momentum, p, and so KE of p^2/2m_cart.

The earth moves, and gains -p, so KE of p^2/2m_earth

The sum of the energy
(p^2/2m_cart+ p^2/2m_earth), must come from the wind, with p^2/2m_earth being transferred to the ground. But the Earth is massive, so that amount is tiny, leaving p^2m_cart to be extracted from the wind.

Gentlemen,

I'm willing to attribute this stuff to a Saturday night drunk! Let me know tomorrow if you want to stand behind these remarks?

Regards,

WindGrins

 

[spork]

When you say defeated what do you mean exactly? Will there be any visible manifestation of the defeat or will it just be in your mind?

There is no chance humber will answer that question. He needs to leave himself an out for the one and only real possible outcome - namely that NALSA will ignore his silliness.

It may be worth pointing out that NALSA has suggested that they do the same thing for the upwind runs as they did for the downwind runs. They asked if we'd be interested in having them develop a set of rules for establishing a directly upwind record. So they don't exactly seem to be trying to distance themselves from the downwind record. I think they were happy to be a part of the whole thing. We were certainly happy to have them do so.

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[Llyricist]

Winnowing the chaff for the smallest of grain. Whining at NALSA to be allowed to take it over.


Not like the image is it?

Are you going to provide an actual mechanism, a technique, or anything at all to explain why the cart accelerated with a relative headwind off the nose of less than 10 degrees with a speed increasing from about 8 MPH to about 20 MPH?

Everyone that claims to have any understanding of physics and/or sailing, and has given the matter any attention at all, understands the actual mechanism that allows this, except you and hyevpranglostoph.

You keep claiming it happened because of things that happened before, or after, it did this.

But it doesn't matter at all what happened before or after, the cart cannot accelerate, much less increase it's acceleration, with its inertia, that is impossible.

 

[69dodge]

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[humber]

There is no chance humber will answer that question. He needs to leave himself an out for the one and only real possible outcome - namely that NALSA will ignore his silliness.

Leaning on secondhand support again.

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[fttw]

I'd like to see profpangloss's work that (he claims) shows the cart can't go ddwftw as claimed.

I'm happy for him to use a frame in which the earth is and remains stationary regardless of the motion of the cart; that will be true in the limit of the earth having infinite mass and there's nothing in the theory of the cart that demands the earth be finite for it to work.

 

[humber]

Are you going to provide an actual mechanism, a technique, or anything at all to explain why the cart accelerated with a relative headwind off the nose of less than 10 degrees with a speed increasing from about 8 MPH to about 20 MPH?

Everyone that claims to have any understanding of physics and/or sailing, and has given the matter any attention at all, understands the actual mechanism that allows this, except you and hyevpranglostoph.

You keep claiming it happened because of things that happened before, or after, it did this.

But it doesn't matter at all what happened before or after, the cart cannot accelerate, much less increase it's acceleration, with its inertia, that is impossible.

 

[humber]

Gentlemen,

I'm willing to attribute this stuff to a Saturday night drunk! Let me know tomorrow if you want to stand behind these remarks?

Regards,

WindGrins

I am not willing to give you that excuse.

I would like to see you challenge that post. Then we can see how well you do.