On Thu, 24 Jul 2003 10:37:55 +1200, The_navigator© wrote:
Of course it still applies.

You tell me!


Technically, that depends on your reference frame. Let's consider the earth
stationary and the rock stationary. Therefore it is not accelerating. Does F=ma
still apply?



S/V Cat's Meow
http://www.catsmeow.org

On Wed, 23 Jul 2003 10:19:23 -0400, "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom
wrote:

f the rock was truly stationary, there was no Force. Unless we want to get into
immovable objects and unstoppable forces.

So gravity stopped working?

S/V Cat's Meow
http://www.catsmeow.org

Yes that aspect always frustrated me. But I think Newton's third law covers it: the force
of the pull is countered by the force of the object pushing back. No net force, no
acceleration. To actually get acceleration, you have to consider the whole system.


"Gerard Weatherby" wrote in message
...
On Wed, 23 Jul 2003 10:19:23 -0400, "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom
wrote:

f the rock was truly stationary, there was no Force. Unless we want to get into
immovable objects and unstoppable forces.

So gravity stopped working?

S/V Cat's Meow
http://www.catsmeow.org

So if a=0 f=0?

Cheers MC

Gerard Weatherby wrote:
On Thu, 24 Jul 2003 10:37:55 +1200, The_navigator© wrote:
Of course it still applies.


You tell me!


Technically, that depends on your reference frame. Let's consider the earth
stationary and the rock stationary. Therefore it is not accelerating. Does F=ma
still apply?




S/V Cat's Meow
http://www.catsmeow.org

Hey! Leave DP and DT out of it (although you may have them mounted
correctly)
;-)
Cheers MC

Jeff Morris wrote:
Oh No! Another blank post - I'm really losing it!

F=ma ALWAYS applies. I was taught in physics that if you're totally clueless on a
question you can always get partial credit for writing F=ma (or F=dp/dt if you really
need another point)

"The_navigator©" wrote in message
...

You tell me!

Cheers MC

Gerard Weatherby wrote:

On Wed, 23 Jul 2003 11:34:39 +1200, The_navigator© wrote:



But it's not accelerating -or is it?


Technically, that depends on your reference frame. Let's consider the earth
stationary and the rock stationary. Therefore it is not accelerating. Does F=ma
still apply?


S/V Cat's Meow
http://www.catsmeow.org

On Thu, 24 Jul 2003 14:20:12 +1200, The_navigator© wrote:

So if a=0 f=0?

Depends, do you still believe "F=ma cannot be correct unless the object
applying/experiencing F also changes energy content!"

Cheers MC

Gerard Weatherby wrote:
On Thu, 24 Jul 2003 10:37:55 +1200, The_navigator© wrote:
Of course it still applies.


You tell me!


Technically, that depends on your reference frame. Let's consider the earth
stationary and the rock stationary. Therefore it is not accelerating. Does F=ma
still apply?




S/V Cat's Meow
http://www.catsmeow.org


S/V Cat's Meow
http://www.catsmeow.org

Another blank post - I'm really losing it!


As I said earlier.

RB

Yes, unless the point of application of the force does not move with the
object there is no acceleration. If the point moves with force applied
enegy content has changed.

Cheers MC

Gerard Weatherby wrote:
On Thu, 24 Jul 2003 14:20:12 +1200, The_navigator© wrote:


So if a=0 f=0?


Depends, do you still believe "F=ma cannot be correct unless the object
applying/experiencing F also changes energy content!"


Cheers MC

Gerard Weatherby wrote:

On Thu, 24 Jul 2003 10:37:55 +1200, The_navigator© wrote:
Of course it still applies.



You tell me!



Technically, that depends on your reference frame. Let's consider the earth
stationary and the rock stationary. Therefore it is not accelerating. Does F=ma
still apply?



S/V Cat's Meow
http://www.catsmeow.org



S/V Cat's Meow
http://www.catsmeow.org

The Bernoulli Principle applies to  sails and is the
principal contributor to moving the hull through the water,
In the case of aircraft jet propulsion.. the jet engines
provide the main forward thrust with the Bernoulli Principle
making a secondary contribution to lift in the countour
contour of the wings.

--
Longing to be closer to to the sun, the wind and the sea!
Spiritually at: Latitude 21 degrees 19' 9" North. _!_
Longtitude 157 degrees 56' 31" West. Aloha! ___o_(_)_o___
q

(Thom Stewart) wrote in message ...
Jan,

Your answers are showing a great lack of knowledge and understanding. I
dought very much that you have read any of these works you 're posting.
If you have
read them then you better get some one to explain what they are saying.
You are screwed up to many ways

Examples; A pitot tube has no air flow thru it. Wind sock does have air
flow thru it
3; Centrifugal force is an outward direction from a inner point, 4; How
can you have Air Velocity in other direction than from high to low
pressure. 5; How Ground effect applies to a sail 6; how does Coander
exits if there isn't isn't a Bernoulli Vacuum created by the curved
surface of the wind 7; Are we seeing the results of Bernoulli, Newton,
coander?

In other word, You tell me. Don't print a Web site and think you are off
the hook. You, yourself, Tell us what the tell-tales are reacting to.
ON A SAIL. That is what this post is about. I don't think you can do
that

Ole Thom

Pims webpage tell you everything you need to know about the physics of
sailing.

http://www.sailtheory.com/index.html

Wings, sails, rudders and curved walls/roofs all works the same way:

Deflecting airflow and thus creating a force, action/reaction!

The Coanda effect causes the air/fluid flow to follow a curved
surface.

Since the airflow always try to go straight ahead as Newton 1 law say,
centrifugal/centripetal forces create local pressure gradients.

Thats the force acting on the curved surface.

A fluid always goes from high pressure to low pressure, just as the
weathermap tells us every day.

The pressure of the airflow on the weather map can never be explain by
the velocity of the airflow. Thats physically impossible.

High airflow velocity can never create low pressure!

Thats only a mathematical manipulation!

There is no "Bernoulli Vacum"!

There are many new websites explaining Lift forces physically correct,
not using mathematical modelled Potential/Circulation Theory,
Conformal Mapping, etc


Jan-Olov Newborg