quade 3 #26 July 9, 2003 I have a similar on-going (at least 15 years now) office argument about the definition of plurals. To wit; do you mean "more than one" or do you mean "two or more"? For example, if you have $1.50 can you say that you have "one and a half dollars"? The real answer is that both are "correct" definitions. Just curious . . . Are you arguing about it because it's amusing or do you really not get the fact that it's just semantics?quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
Clownburner 0 #27 July 9, 2003 You're really not grasping relativity here. It's all based on frame of reference. I'll try and provide a very simple example: If you and I are moving the same speed in the same direction, and suddenly you slow down, from my perspective you seem to be 'accelerating' away from me. If a third person is standing still and we're going past them, when you slow down, he still sees us both moving but sees you 'decelerate.' So they're really the same thing seen from two different perspectives. Poynter's manual is titled "aerodynamic decelerators" because seen from a ground-based point of reference, that's what they do. But if you're looking at them from the perspective of a camera in freefall, they're causing the deploying jumper to accelerate away from you. It's like when you're adjusting your fall rate, and you 'float' above another jumper. You aren't floating. In fact, from a ground-based point of reference, you're still hurtling at the earth at an amazing speed. But from your perspective, you see the other jumper move away from you. If you didn't move, you assume the other jumper ACCELERATED but from his perspective you might easily have DECELERATED. No difference. Does this make more sense now? EDIT: Of course, this is all pretty academic considering this thread was supposed to be about double-stowing line/locking stows. 7CP#1 | BTR#2 | Payaso en fuego Rodriguez "I want hot chicks in my boobies!"- McBeth Quote Share this post Link to post Share on other sites
alan 1 #28 July 9, 2003 Quotebut if einstein taught us one thing, it's that you have to define your frame of reference and stick to it. The ground (a good frame of reference for skydiving purposes) always seems to be there, the observer on my back.......very seldom, and to date, never as my d-bag decelerates away, although I've had a few tandem passengers on my front. REALLY. As I stated previously, you, the pc, the d-bag, the harness/container, and even the observer are all travelling towards the Earth (same thing as the ground for our purposes) at about 176 feet per second. After you let go of the pc, it is no longer travelling at Earth at 176 feet per second, but at increasingly slower rates over time. You on the other hand continue at 176 feet per second for a brief period of time, until the drag of the pc pulls the pin, decelerates the d-bag and the canopy (aerodynamic decelerator) goes through the opening sequence and ultimately decelerates you (and your observer if he/she is still attached) to something around 15 feet per second, which is what the pc and d-bag are now doing. Hey Bill, you're out in Poynter country, heck you've probably even met the man. Perhaps you could find out why he did't call the book something about aerodynamic accelerators or aerodynamic negative accelerators.alan Quote Share this post Link to post Share on other sites
alan 1 #29 July 9, 2003 QuoteAre you arguing about it because it's amusing or do you really not get the fact that it's just semantics? Partly because it is amusing and partly because there seems to be an abundance of very knowledgeable people who don't seem to be able to grasp frame of reference. It is the ground. I stated that very clearly in my first reply to you. That by the way, is what has made this amusing. Semantics? Naw, if it was just that I wouldn't care.alan Quote Share this post Link to post Share on other sites
alan 1 #30 July 10, 2003 QuoteYou're really not grasping relativity here. No, I grasp it very well thank you. QuoteIt's all based on frame of reference. My point all along. Quote I'll try and provide a very simple example: No need, I understand it. So, what is it doing from the perspective of someone in the airplane? You see, as Bill stated, if we have to learn one thing from Einstein, it is we have to define our frame of reference and stick to it. I clearly defined it as the ground. Seems to a constant with respect to skydiving. QuotePoynter's manual is titled "aerodynamic decelerators" because seen from a ground-based point of reference, that's what they do. Seems as if my perspective coincides with Mr. Poynter's. Does yours? QuoteBut if you're looking at them from the perspective of a camera in freefall, they're causing the deploying jumper to accelerate away from you. But the ground is the constant. I just used that as an example to illustrate the illusion it creates. The whuffos don't ask, "Why are they accelerating?", they ask, "Why are they going up?" Frame of reference, perspective, point of view, relative to (fill in the blank). If you want to pick and choose your reference, than why not the plane? After all, you just left it, it was your point of origin from one perspective. Quote Does this make more sense now? It has all made perfect sense all along. I guess it just depends on your perspective. By the way, I understood it when I read Enstein's description illustrating it using two trains sitting side by side. Hint: jumping from an airpalne is not a theory, you and everything/everybody with you will be travelling towards Earth.alan Quote Share this post Link to post Share on other sites
masher 1 #31 July 10, 2003 QuoteQuoteThe energy doesn't change exponentially as velocity increases; it's only a quadratic increase. That's much slower. Again, bad schooling/learning on my part. We were taught that in velocity^2, that the 2 was called an exponent. Hence I derived the increases exponentially. By the way, what is the 2 in this case called? The 2 is the exponent. When you have a variable raised to a power, it is a polynomial. The power is constant, be it 2, -3 or pi. An exponential has a constant raised to a variable. Hence 3^x or something like that. If you compare y=x^2 to y=2^x, then the 2nd equn is going to shoot off to infinity a lot faster. . Acceleration is acceleration is acceleration. The direction of which is given by the sign of the number out the front. Deccelerate is a term that has come into common usage, used to denote 'slowing down'. It doesn't really do any harm to use it, but to be technically correct, you should use accelerate. It's a bit like centrifugal force. Engineers like it. It makes their calculations easier. Physicists hate it, centrifugal force doesn't exist, it's just inertia. I think at this point we should agree to disagree on the pedantic nature of this discussion. Everyone is talking about the same thing, and what they are saying is correct. No-one is saying anything wrong here, it's just a matter of terminology and the level of understanding that you need to go into.-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
redshift 0 #32 July 10, 2003 Since this thread's already deeply pendantic, I thought I'd throw this in: the word is "bight", not "bite". A bight is a loop, as in a rope, or a river. And before I get slammed for correcting folks' language, note that "bite me" is another usage altogether.... Quote Share this post Link to post Share on other sites
andy2 0 #33 July 10, 2003 thanks redshift. I didnt know anyone was still reading this that wasn't a physics major. --------------------------------------------- let my inspiration flow, in token rhyme suggesting rhythm... Quote Share this post Link to post Share on other sites
alan 1 #34 July 11, 2003 QuoteThe 2 is the exponent. It is obvious then that you could understand my confusion when the 2 represents an exponent and I thought that raising a number by that power meant exponentially. You know, there is a certain similarity between exponent and exponentially. QuoteIf you compare y=x^2 to y=2^x, then the 2nd equn is going to shoot off to infinity a lot faster. But what if x=2? QuoteIt doesn't really do any harm to use it, but to be technically correct, you should use accelerate. Even if I'm slowing down? You don't understand that it is a bad thing to accelerate as you approach a red light in heavy traffic? Oh, I get it, you only accelerate realtive to the guy who runs the red light, at least from his perspective. I have some friends in the police dept., they're gonna love this! Quotecentrifugal force doesn't exist, it's just inertia. Inertia is a property of matter by virtue of which any physical body persists in its state of rest or of uniform motion until acted upon by some external force; its quantitative expression is mass. Centrifugal force however, seems to be the inertial reaction of a body against a force constraining to move it in a curved path. QuoteI think at this point we should agree to disagree on the pedantic nature of this discussion. Everyone is talking about the same thing, and what they are saying is correct. No-one is saying anything wrong here, it's just a matter of terminology and the level of understanding that you need to go into. OK, but I'm still not going to accelerate when I approach a red light in heavy traffic, well at least if you aren't the observer in the car running the red light. Can I get a ticket for accelerating through a red light even if I come to a complete stop? Us laymen....we just don't get anything!alan Quote Share this post Link to post Share on other sites
indyz 1 #35 July 11, 2003 QuoteCan I get a ticket for accelerating through a red light even if I come to a complete stop? Bogus example. If you go through the red light you didn't come to a complete stop. Anyway, I'm done with this. After this and the repack cost thread, you've gone from a former moderator whose opinion I respected to nothing better than a common troll in my mind. Quote Share this post Link to post Share on other sites
1234hutch 0 #36 July 11, 2003 I think this thread should look at the issues of snatch force and openning shock. And as examples of functions of each do a comparision ccontrast between a free baged square reserve ( NO line stows and a long bridle) and a main ( short bridle many line stows) hutch Quote Share this post Link to post Share on other sites
masher 1 #37 July 11, 2003 Exponent and exponentially - totally understand. -- y=x^2, y=2^x. If x=2, then the two equations return the same value. They also return the same value at x=4. FYI I've attached graphs of the functions. the red one is x^2. -- Acceleration. I'm not doing anything else here. Please read previous posts -- Centrifugal force. Not going there, it's going to degenerate into an acceleration type arguement.-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
quade 3 #38 July 11, 2003 QuoteI think this thread should look at . . . This thread has been side tracked already! The real answer was given long, long ago and has been almost totally burried in this thread . . . follow the manufacturer's directions. Simple.quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
