MadBill wrote: ↑Fri May 17, 2019 12:11 pm
It doesn't matter in which direction the air is accelerated, since it is in effect a neutral buoyancy situation. Consider for example a two foot diameter beach ball filled with freshwater. Its volume is 4/3 π r³, so 4.189 cubic feet, weight 62.4 lb./C.F. x 4.189 = 261.4 lb. If the ball is dropped into a swimming pool, it will have neutral buoyancy, just hanging there at whatever height below the surface.
Yes Bill. But, what color is this beach ball of which you speak?
n2omike wrote: ↑Fri May 24, 2019 1:31 pm
This thread is running off the rails. I'm out.
Carry On...
You haven't been on the rails once in this thread because you don't recognize that acceleration vectors are additive. Gravity is an acceleration force and the G vector is always the same. When the air is accelerating, during the time it is actually changing velocity, the acceleration vector of gravity is part of the overall equation that determines the final velocity resulting from the acceleration.
It's been explained to you multiple times that an object AT EQUILIBRIUM has a net force of ZERO. Any forces applied (gravity) to this object are already counterbalanced. Therefore, the gravity has ZERO NET AFFECT.
Do as MadBill said... Submerge a water balloon, and poke it from various sides... and SEE if it accelerates any faster down than it does up or sideways. If you're objective, you'll see that it is THE SAME.
A submerged water balloon has a neutral buoyancy... as does an air mass.
The buoyant (upward) force is equal to the weight of the displaced volume of the media it's in.
A one quart water balloon displaces one quart of water... so the buoyant force is equal to its weight. It's weight is cancelled out, so it just hovers there. If it was filled with air, it would shoot to the surface. Filled with mercury, it would drop like a rock. But filled with water, it just hovers as it's weight is equal to the buoyant force. The exact same occurs with an air mass. It's buoyant force is equal to the volume of air it displaces.
To make the 'air' example easier to see, consider an hot air balloon. Before the air is heated, there is no net buoyant force. It does not rise. Once the air is expanded with heat, the weight of air it displaces is greater than it's own... so there is a net upward force... and it accelerates upward.
An air mass of the same temperature as the air around it has a buoyant force of ZERO. Gravity is cancelled out, and has ZERO net affect.
It's a VERY SIMPLE concept.
At what stage in a running engine is the air in the inlet tract at equilibrium? It doesnt seem to be a condition that would be present unless the engine was turned off?
BenE64 wrote: ↑Fri May 24, 2019 3:50 pm
At what stage in a running engine is the air in the inlet tract at equilibrium? It doesnt seem to be a condition that would be present unless the engine was turned off?
That's the point... The air is at equilibrium before the pressure differential from the engine acts on it... So, that pressure differential is the SOLE accelerating force acting on the air. Gravity has nothing to do with how the air accelerates. The gravitational force is already counterbalanced.
When the human mind has resolved an ambiguity or parsed information and imposed order onto it it can be VERY difficult to undo that.
It is possible. Samantha knew French, German and English as a child. Her parents were told to stop this and now she remembers her German Oma, who only spoke German, speaking in English in her memory.
Happens in vision science too.
Maybe it is best to agree to disagree. Both perspectives have validity.
The arrow
If everything when it occupies an equal space is at rest, and if that which is in locomotion is always occupying such a space at any moment, the flying arrow is therefore motionless.
MadBill wrote: ↑Sat May 25, 2019 12:28 am
I KNOW I'm right because....ah...BECAUSE! I just know it!
Yes, Bill... You ARE correct! It's fairly basic science.
It's not a matter of feelings, opinions, etc... just how it is!
Sorry Mike, I should have been clearer: I was making an apocryphal quote on Tuner's behalf. (and sorry Tuner, I'm not trying to fight or belittle you, just open your mind; I know by your many insightful S/T contributions that you are an intelligent and knowledgeable guy. My info sources on buoyancy and effects of gravity is my high school and college level physics texts and classes plus dozens of books, internet references and more.)
One of the things that I noticed in high school and college physics was that paradoxes of time and motion were studiously ignored other than to get a chuckle from the class as to those ancient Greek philosophers. The philosophy of science did explore why these considerations were ignored. Short story: pragmatism. Newton was wrong about time and space? Get real, dude, your mortgage payment is due. Zeno's Paradoxes were what I wrote my undergrad Honors thesis on.
Funniest thing. I explored the U-505 as a kid. Watched lots of movies about submariners. Learned about neutral buoyancy, crash dives (Tauchen, tauchen, tauchen!!!), blowing the tanks, etc. It was pretty cool that a submarine was a system within a system; forget that at your peril.
Systems do communicate. That's the lingo that engineers like.
408swinger wrote: ↑Sat May 25, 2019 10:56 am
My wife says I always think I am right ...
My response is " Of course I do... if I thought I was wrong I wouldnt have said it ! "
My Dad learned me on this one: "I thought I was wrong once but I was mistaken." British humour.
MadBill wrote: ↑Sat May 25, 2019 12:28 am
I KNOW I'm right because....ah...BECAUSE! I just know it!
Yes, Bill... You ARE correct! It's fairly basic science.
It's not a matter of feelings, opinions, etc... just how it is!
Sorry Mike, I should have been clearer: I was making an apocryphal quote on Tuner's behalf. (and sorry Tuner, I'm not trying to fight or belittle you, just open your mind; I know by your many insightful S/T contributions that you are an intelligent and knowledgeable guy. My info sources on buoyancy and effects of gravity is my high school and college level physics texts and classes plus dozens of books, internet references and more.)
Same here. I'm not trying to be mean, either. My apologies if I came across that way. I've taught Honors Physics for 26 years, and was just trying to show how things work, more than anything. MANY of today's kids could learn a LOT from Tuner's stubborn drive and tenacity! Questioning current assumptions is how we learn and move forward! It's something that is highly lacking nowadays!
