NORDHAVN Rewrites Physics Textbooks
 

wrote in message
ups.com...
Gravity does not exist at the LaGrangian point.

Yes it does. Gravity always exists. At a LaGrange point, the gravity
of one mass is cancelled by the mass of another. So gravity has no
effect on free bodies at a LaGrange point, but gravity still exists.


"Bill" wrote:
How does one know it exists there? By measuring it? Or by postulating it?
If gravity of one mass is cancelled by another then it does not exist,
the
net force is zero.

There is a big difference between "does not exist" and "net force =
zero."

Yes there is. But how does one tell the difference?



... Zero means nothing. Anyway, you are completely wrong.
Gravity can be higher at a Lagrangian point provided it is countered by
acceleration forces. It says so on this NASA website:



So, you said gravity doesn't exist, now you say that it not only may
exist but that those who know most about it say it is greater; then
you say that I'm "completely wrong."

Good work.

The good work goes to you. You've parsed out all of the previous thread to
only the above point. Why is that?

You said gravity cancels at the Lagrangian point. I said it does not exist.
For simplicity let's throw away the L2, L3... Langrangian points and deal
with just the L1 point since it can be argued that in a first order case
there is no net gravity at that point. Agreed?

You say the gravity there exists but it cancels to zero.

I say the gravity does not exist because it is zero.

Of course we are talking of the total or net gravitational field at a point
in space. Now if you were in a black box at the L1 point and not aware of
the external cicrumstances and took out your gravitometer and measured zero
what would your conclusion be? Would it be there is no field here (Occam's
razor) or would you conclude that there are bodies nearby in such
arrangement to have their fields cancel? Remember you are in a black box.

So tell me of an experiment to be performed at a single point in space that
can resolve all the gravitational vectors upon that point.

Is there no gravity at the center of the earth or is there lots of gravity
that just happens to cancel to zero?

Since when does the quantity zero imply the existence of anything?

As far as being completely wrong, you are. Here is a bit on the LaGrangian
point:

http://en.wikipedia.org/wiki/Lagrangian_point

"The Lagrange points mark positions where the combined gravitational pull of
the two large masses provides precisely the centripetal force required to
rotate with them."

This is not what you said, you only considered gravity.




I look forward to your help and comments with my replies to your
scientifically astute and accurate commentary. It's not often we get
someone
here who really knows their **** and is willing to help others. Thanks
immensely.


You're welcome immensely.

I'd like to be regraded. You said:

"In other words, "Bill" you flunked the physics test and you don't know
as much as you think you do."


But you didn't know who Milliken was, you believed he was like the Amazing
Kreskin; you weren't aware of Einstein saying the gravity field ceases to
exist for an observer in a free fall; you mistook my single clock running at
two different rates for two different observers as 2 clocks in different
inertial frames, disagreed with what I said and then essentially restated
what I said to make your point; you failed to account for the increase in
oscillation velocity of a photon in a gravitational free fall even though
its translational speed remains constant; you have not defended your
position that not all realized energy involves movement, which it does; you
claim that things exist when measured to be zero and exhibit no effect what
so ever on test particles. In view of these oversights on your part would
you kindly regrade the physics test? I am but a simple student/observer of
natural philosophy seeking direction.

I'll gladly admit any mistakes I have made if you kindly point them out. I
just don't see how I deserve a failing grade or how you can possible
estimate how much I think I know about physics.The bottom line is it's not
what you think you know, it's what you can prove, measure and demonstrate. I
tried to do that with all the points we disagreed upon to the best one can
do in a single USENET post. It now seems the only point left with which we
disagree is that you say:

Even though gravity measured is zero it is really there but cancels itself.

And I say:

If gravity is measured to be zero, it (gravity) does not exist at the point
of measurement.

My statement is the fundamental law of identity A---A A is A. A being
"zero" or "non existence".

Your argument is A----A+*A. This essentially says that A can be itself plus
elements that are not itself. Carrying it one step further by making A to be
zero, you are making nothing to be made up of constituent elements that when
added make it zero, but the elements are still there, existing beyond all
senses and measurement.


entia non sunt multiplicanda praeter necessitatem

Bill

NORDHAVN Rewrites Physics Textbooks
 

wrote in message
ups.com...
On 15 Oct, 17:56, "Bill" wrote:
"toad" wrote in message

ups.com...





On 15 Oct, 16:20, "Bill" wrote:
"toad" wrote in message

The guy who built the windmill boat could be a lying crackpot. I have
not
seen one with my own eyes so your point is valid.

You wouldn't have to lie. Natural wind isn't all in one direction. You
could be steaming ahead in your windmill boat on the components of the
wind that are not directly on the nose and really believe yourself to
be sailing upwind. Pyro actually posted a picture of his cart working
- but in the photo he was blowing downwards on it. He wasn't lying, he
realy did think it was going upwind, he just didn't have a handy head
protractor!

It's also worth noting that some of the windmill craft identified in
the course of this 'debate' as craft that could sail directly into
wind turn out to be incapable of going direct into wind!

It's a futile to debate this in words. We need figures. It will be
resolved one day when somebody who genuinely knows (as opposed to
guessing based on gut feeling and justifying it with wordy posts using
analogies) simply posts the worked formula to prove it one way or the
other.

You only have to look at the Conundrum thread to realize just how much
of a pinch of salt you have to take with armchair physicists on usenet!

If the windmill did work we could put small wind turbines on bicycles and
reduce the pedaling load for cyclists and even increase their speeds into
strong headwinds.

Forget that, you could put windmills on the bonnets of sports cars,
gear their output to the drive and turn that 100mph headwind into even
more power.


I have a scheme for tapping into the power of the rotating earth. I even
built an apparatus that worked for several years. Michael Faraday built a
small scale device working on the same principle. It is not perpertual
motion or any crackpot scheme. It does slow down the rotation of the earth a
little and causes local weather changes (on a very small scale).

Bill

NORDHAVN Rewrites Physics Textbooks
 

toad wrote:

Do you accept that it is possible for the cart to move directly upwind?

It is essential that we assume that to be the case so you can explain
the paradox exposed by the windmill on powerboat example.

Is that yes?

If in a headwind the windmill pushes back harder than it is pushed
then it must do that no matter how that headwind comes about. Which
leaves us with a power boat with a windmill on it's foredeck getting a
net gain in energy from wind that it is creating.


OK. Let's assume wind at 1m/s (I like metric - but that's about 2 1/4
MPH)) and a nice simple force on the windmill of 1000n. (~10Kg, or 20lbs
- ish) Neglecting losses, you get a kilowatt out of the mill - 1000n at
1 m/s.

Suppose you use that kilowatt to pull the anchor cable. Again,
neglecting losses, it ought to be able to pull the winch in at 1m/s,
because the force is the drag on the mill.

However, you do have losses. Say the whole system loses half the power
(in drag on the boat, turbulence around the blades, losses in the
generator, etc) You can then wind in the winch at only 1/2 m/s.

Now it doesn't matter how much you lose, you will still have some power,
and you will still be able to wind the winch in.

Back to the 50% loss case. You're winding the winch at 0.5 m/s, and the
wind is 1 m/s. Hey look, the apparent wind has gone up - you get more
power. Yup, as the force has gone up to 2.25 the original value (it's
proportional to the square of the wind speed) and the speed has gone up
- so the available power is now the cube of 1.5, a tad over 3. You can
wind the winch in faster, the wind goes up, you're away. EXCEPT the
drag went up too - by 2.25 times - and as the speed goes up, the power
goes up too. You'll find it more than cancels out - which was the point
of the spreadsheet I posted the other day.

It's a bit different with a prop in the water, not a winch, because a
prop. will require some power just to hold still - but not fundamentally
different.

Now the windmill on the deck of the power boat - lets stick with the
1000n force & 1m/s. (OK - Canal boat?). The windmill is going to get
its kilowatt out of the air. But the power boat has to push it through
the air, against that 1000n drag. Because of losses, you'll need *more*
than a kilowatt of engine power to overcome the extra drag of the mill,
but you'll only get a kilowatt, at best, out of the mill. Less than you
put in.

Remember that a stand-alone windmill cannot produce a forward force. It
can only generate power that something else can make into a forward force.

Are we there yet?

Andy

NORDHAVN Rewrites Physics Textbooks
 

There is a big difference between "does not exist" and "net force =
zero."

"Bill" wrote:
Yes there is. But how does one tell the difference?


By pondering the difference between physics and semantics.

If they were the same thing, we wouldn't need two different words for
them, now would we?


I'd like to be regraded.


True.
Very good, your average is improving.

Please provide more details on your machine for using the Earth's
rotation as a power source. Sounds like a great idea as long as we can
keep it a secret from Al Gore.

DSK

NORDHAVN Rewrites Physics Textbooks
 

On 15 Oct, 19:17, Goofball_star_dot_etal
wrote:
On Sun, 14 Oct 2007 11:57:47 -0700, toad
wrote:





On 14 Oct, 19:38, Andy Champ wrote:

Same speed *relative to the the surface it is on*.

Yes, so you accept it has spare energy left over after it has overcome
the drag of the windmill. So the windmill on the foredeck of our power
boat has enough energy to push against the wind pushing back on it. It
also has enough energy left over after this to move it forwards.

Which means you can gear that spare energy to the engine and save some
petrol.

Yet you and I both accept you can't do that.

So there's a paradox.

In other words there is some spare energy left over to drive the cart
forwards after the energy required to hold the windmill in equilibrium
with the wind is expended. In my example above that spare energy is
used to drive the cart forwards but in your example of the windmill on
the foredeck that surplus energy can be used to save petrol.

Now we both accept that idea is laughable so you have to explain why
it's not laughable when the wind blowing is caused by nature.

...but most importantly, why oh why oh why doesn't someone just post
the mathmatical proof, the last time this came up I said I'd leave the
thread 'till proof turned up and none did. Odd that.

Lets take this step by step.

Or to put it another way "Lets take this step by step so I can keep
talking rather than posting the maths that I claim is simple to prove
my case."

Do you accept that it is possible for the cart to move directly upwind?

It is essential that we assume that to be the case so you can explain
the paradox exposed by the windmill on powerboat example.

If in a headwind the windmill pushes back harder than it is pushed
then it must do that no matter how that headwind comes about. Which
leaves us with a power boat with a windmill on it's foredeck getting a
net gain in energy from wind that it is creating.

No it gets energy from a reduction of the kinetic energy of the _true_
wind.

To the windmill there is no difference between wind powered by the sun
(in your terms true), or wind created by the diesel of the engine. (in
your terms apparent).

If I put a windmill in a 20kt wind and it makes 1kw, I can put the
same windmill on a powerboat on a still day at 20kts and it will still
make 1kw.

Now if that 1kw is enough to push the windmill forward against the
wind then that energy surplus will also exist for the windmill on the
power boat so if you gear it to the prop shaft, after the drag of the
windmill has been equalized, there will be some power left over to
save some diesel. This is patently absurd so if you buy the idea the
windmill boat/cart can drive forward into wind you have to explain
this paradox away or explain how 20kts of wind created by diesel is
different to 20kts of wind created by the sun.

Anyway, I'm going to do what I did last time and ignore this thread.

I'll revisit the thread in a few days time and if someone has posted
the correct equations and worked it through with figures to show the
windmill cart/boat can move directly into wind I shall post to
acknowledge my acceptance that it is possible. Otherwise, I shall post
nothing.

NORDHAVN Rewrites Physics Textbooks
 

On 15 Oct, 20:11, "Graham Frankland"
wrote:
"Ian" wrote in message

ups.com...

On 15 Oct, 14:19, (Richard Casady) wrote:

Thrust from the engine, of course.

My own aircraft has a take off mass of 370kg and no thrust whatsoever,
and yet I can get it to go up.

But in your example, gravity is still causing you to descend through the
air. Unless converting excess speed to height, you only climb because the
air in which you are flying is rising faster than your sink rate.

Whether in a zoom or a thermal, I can get my glider to rise without
smuch as a millinewon of thrust...

Presumably, if a boat's motion is generating apparent wind from dead ahead
and a fully battened sail (I say fully battened because it's a better
aerofoil shape) could be set far enough out to achieve sufficient angle of
attack to produce some lift, then a keel boat "may" go a little quicker.

Nope. Lift is - by definition - always at right angles to the free
stream air velocity. You might get the boat to go sideways a bit, but
the assoiated drag will always slow you down as you do.

Ian

NORDHAVN Rewrites Physics Textbooks
 

On Mon, 15 Oct 2007 13:00:43 -0700, toad
wrote:

On 15 Oct, 19:17, Goofball_star_dot_etal
wrote:

snipped some

No it gets energy from a reduction of the kinetic energy of the _true_
wind.

To the windmill there is no difference between wind powered by the sun
(in your terms true), or wind created by the diesel of the engine. (in
your terms apparent).

ok. By "true" I assume no tide in this case. The frame of reference is
the water and velocities are measured wrt to the water/land


If I put a windmill in a 20kt wind and it makes 1kw, I can put the
same windmill on a powerboat on a still day at 20kts and it will still
make 1kw.

ok.


Now if that 1kw is enough to push the windmill forward against the
wind then that energy surplus will also exist for the windmill on the
power boat

Just a minute.. (k) watts are units of power not energy. If you are to
make sense of this you cannot mix your units and dimensions of force,
energy, power, momentum etc. It might sound pedantic but it is
absolutely fundamental that the dimensions on each side of an equasion
match


so if you gear it to the prop shaft, after the drag of the
windmill has been equalized, there will be some power left over to
save some diesel. This is patently absurd so if you buy the idea the
windmill boat/cart can drive forward into wind you have to explain
this paradox away or explain how 20kts of wind created by diesel is
different to 20kts of wind created by the sun.

Assuming no wind in this case, the affect of driving this windmill
forward will be to increase the velocity of the air from zero to a
finite value. In other words the kinetic energy of the air has
increased, therefore you are doing work not extracting energy, at some
rate. (same units:-) ) You must be losing power.


Anyway, I'm going to do what I did last time and ignore this thread.


ok, bugger off if you must..


I'll revisit the thread in a few days time and if someone has posted
the correct equations and worked it through with figures to show the
windmill cart/boat can move directly into wind I shall post to
acknowledge my acceptance that it is possible. Otherwise, I shall post
nothing.

NORDHAVN Rewrites Physics Textbooks
 

toad wrote:

Anyway, I'm going to do what I did last time and ignore this thread.

In case you don't, this needs a face to face discussion with drawings
(and possibly beer!). Whereabouts are you?

Andy

NORDHAVN Rewrites Physics Textbooks
 

Bill wrote:
My flashlight shoots out photons at the speed of light and it is powered by
a 1 1/2 volt battery. Even better, my flashlight moves away from the photons
at the speed of light with the same 1 1/2 volt battery. When do I need to
change the battery?

Change the battery when it runs down to the point that your photons &
flashlight are only moving apart at about 90% of C grin.

NORDHAVN Rewrites Physics Textbooks
 

On Mon, 15 Oct 2007 07:49:45 -0700, toad
wrote:

On 15 Oct, 14:27, (Richard Casady) wrote:

Why wouldn't it accellerate indefinitely with no friction anywhere in
the system.

....because as it approaches the speed of light it will require
infinate energy.

Of course not. It will continue to acquire kinetic energy at the same
rate, so many foot pounds per second. It will mostly get heavier
rather than going faster My 'calculator that takes no prisoners',
[HP48] will do the calculations for E=MC^2. Without a calculation I
will say that it would take a long time to double the mass, but there
is no upper limit if you have the source of power.

Casady