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Post by lordoftherings on Oct 2, 2005 4:50:38 GMT -4
No, it's just being flung upward. It takes time for gavity to counter the upward motion of the dust that the wheel has given it.
But is this consistent with the claims about dust. First, they say that the dust should fall instantly bcz there is no air to hold it, and say that this is consistent with the dust behaviorin the moon photos. Then, they say that the lack of gravity and the horizontal motion should make the dust slow to fall down. I am confused here.
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Post by lordoftherings on Oct 2, 2005 5:01:30 GMT -4
What if there were dryness in the place the shots were taken at?
Then moisture won't be the reason for clotting. Cohesive cementation occurs for lots of reasons. It the case of a tire digging up dust, it can just be temporary compression; the dust "sticks" together only as long as the tire is pressing it against the denser dust below.
Didn't understand yout point. What do you mean by pressing it against denser dust so it sticks to gether?
There is a space between the dust of the front weel and the ground, indicating there is air, even if few, holding it.
No, it's just being flung upward.
Being flung upwads , they shouldn't take that long to go down. They take inches of ground where they just start to touch the ground at one point, while being hung up . Aren't those few inches too much for the moon env.?
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Post by lordoftherings on Oct 2, 2005 5:07:32 GMT -4
Quoting the Rob Moore article :"I was speaking with one scientist about just the fact that dust should have blown hundreds of feet in the air, so I speculated that since there was no atmosphere and the gravity were weak that the dust might take hours to settle down. I was thinking that there should have been some sort of heavy dust cloud just floating around for hours (like things do float around in space). My Phd friend told me no, just the opposite. He said when there is a total vacuum, no atmosphere, then there is nothing to slow down the descent of the dust. Even though the gravity is 1/6th less on the moon, because there is no air or atmosphere there is nothing to slow down the dust. Therefore, he concluded the dust would fall at a very fast speed, even if it blew hundreds of feet into the (non-air?) "
He was thinking that gravity would slow the dust, but his phd friend told him that it should fall straight down, even if cicked hundreds of feet.
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Post by Data Cable on Oct 2, 2005 6:37:32 GMT -4
First, they say that the dust should fall instantly bcz there is no air to hold it I don't believe anyone has said that "the dust should fall instantly." What's been said is that each individual particle will follow a ballistic (parabolic) arc influenced only by its momentum (induced by the wheel) and gravity, with no contributing factors such as air turbulence to induce it to do otherwise (i.e., form a lingering cloud of fine particles). Dust falls more slowly in 1/6g than it would in 1g, as does anything else, regardless of the presence or absence of air. [edit:] I'm going to amend the above statement. An object will fall more slowly in a 1/6g vacuum than in a 1g vacuum. Given equal gravity, an object will fall more slowly in air than in a vacuum. How much more slowly will depend on its drag coefficient, ranging from "negligible" to "easily lofted on the tiniest air current." So an object with a very high drag coefficient (such as, say, a feather) might fall more slowly in 1g air than it would in a 1/6g vacuum, whereas an object with a low drag coefficient (such as, say, a bowling ball) wouldn't. This is what is meant by air "slowing down" an object's descent. It doesn't mean that the absence of air will result in all objects "instantly" falling "straight down," only that air is no longer a factor. Gravity and momentum still apply.
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Post by PhantomWolf on Oct 2, 2005 7:06:33 GMT -4
okay, we'll try this really slow, because it's obvious you don't understand the physics, or the big words Jay's so fond of. This isn't your fault, you seem to have had no physics training, and english is a dog at the best of times.
There are a lot of forces occuring in the images, so we'll try and break them down.
Obviously Gravity is a major one. This is pulling everything directly towards the surface. This force is active regardless of where an object is. It is pulling everything down with a force that will apply an acceleration of 1.667 m/s² (1/6th Earth's.) Next we have the Rover. The engines apply a rotational force to the wheel. This is called Torque. That force rotates the wheel at a velocity about 19 km/h. If we just held the rover above the surface, the wheels would spin without anything happening. However, by placing it on the surface we add a force between the metal mesh of the tyre and the surface. Because the surface is dusty, the mesh picks up the dust and translates its motion to the dust. Depending on the size of the dust it is ejected from the mesh at a different point.. Generally the finer the dust the more it takes to eject it, thus the longer it stays on the wheel. This is why we see the very fine dust falling off the front of the wheel. It is too small to be given enough velocity to leave the wheel so it is csrried around the wheel until the mesh that scooped it up is behind it and gravity just pulls it out. The larger pieces are given a velocity with two arts, an upwards part and a backwards part. As soon as it leaves the wheel, gravity is starting to accelerate it towards the surface, but because it has an upward velocity, it takes time to slow it down, just as putting on the brakes of a car doesn't stop it instantly. Once the dust's upward velocity has been countered, it starts downwards until it hits the surface. If the dust only has an upwards velocity it wuld look like a ball being thrown up and dropping, it'd just fly up, slowing till it stops, and start to speed up as it drops straight down. However because it has a backwards component, the dust follows an arc shape, a parabolic curve, just like if you threw a cricket ball out to a fielder, it would go up, peak, then then drop, picking up speed as it does. The dust is a little more complex however. Because different weighted dust comes off the wheel in different places, you get a stream of dust that forms the rooster's tail. There are gaps in this because when the wheel isn't in contact with the ground, there is no dust being kicked up.
Now, if the rover was on Earth in air, what you would getis a similar sitution, except that the air would hold up the smaller dust particles. As a small particle of dust is attracted by gravity, it hits air molecules, which slow it down and so it floats. This is what causes a dust cloud. On the moon there is no air to slow the dust down so it -must- accelerate towards the surface at 1.6667 m/s². That means that dust will fall down quite quickly, but it will do it under the standard ballistic path. This is what we see with the rover. The dust describes an arc regardless of the particle size, there is no air to hold any of it up and form a cloud. This is what was being pointed out in your last post. The dust can't "float about" because the moon's gravity accerates it towards the surface at a set rate. It would need air to hold it up and prevent that acceration and form a cloud. It still -has- to lose it's upward velocity though, so it can't just fall directly to the ground.
Again think about a ball. If you throw it up, it doesn't just fall down straight away, it slows as it goes up, peaks and then falls. The dust does the same on the moon.
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Post by lordoftherings on Oct 2, 2005 7:31:19 GMT -4
I ambasing my point on the PHd person I quoted. He said it has to go down quickly. You are right that I am not into physics, but I am willing to learn. I guess by your explanations, you need to debate them with a PhD person, but I will try to search about that on the net.
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Post by PhantomWolf on Oct 2, 2005 8:27:28 GMT -4
I ambasing my point on the PHd person I quoted. He said it has to go down quickly. You are right that I am not into physics, but I am willing to learn. I guess by your explanations, you need to debate them with a PhD person, but I will try to search about that on the net. No need to debate it with him, he's right with what he says. The suggestion was that the dust would hang around as a cloud due to the low graviity, and he said no, it'd drop down quite quickly, and it will. A few seconds is very quickly compared to the idea offered of a few hours. What he didn't go into is the fact it has to follow the ballistic path, it -CAN'T- do otherwise, Newton's Laws of motion demand that it act that way. The initial upward motion given to it by the wheel MUST be negated before it can gain a downward motion. That is how the Universe works. Look at this figure below, it's crude, but hopefully it'll help. In the top three images yu can see that the three paths are exactly the sme regardles of the particle size (large, medium, or small) The only forces involves are from the wheel (f1) and Gravity (g). If we lok at the three below then you can see there are two other forces present a1, and a2. These are air resistance and they both hold up and slow down the particles so that the path is not perfect but rather is flattened at the end, and in the case of the small particle, it is stopped and held up by the air to form a cloud.This is the behaviour that is not seen in the Rover footage.
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Post by margamatix on Oct 2, 2005 13:51:58 GMT -4
Please examine the video of the TeleTubby moon walkers, here www.futuresunltd.com/sudarshan/realaudio/Ap16_TeleTubbyMoonWalkers.rmThere are two astronauts in this clip. The camera followes the closest astronaut, who moves in the strange skipping gait often seen used by astronauts. But look at the rearmost astronaut. He is simply walking, left right, left, right, using exactly the same perambulation as someone moving on Earth. A totally different motion. Why is this? Incidentally, I see that Lunar Orbit has felt fit to introduce a new set of rules, and I reproduce part of them here....... 9. Getting Yourself Banned I try to be a fair man, and I do not enjoy banning people. If you follow all of the above rules you should be safe. You might even get away with breaking one or two of them occassionally. However, repeatedly breaking any of those rules may result in getting banned either temporarily or permanently. The decision to ban someone is entirely up to the administrator. It won't always be fair. I will take a user's past behaviour into account when they break a rule... if they made 1000 posts without breaking a rule and then suddenly went crazy and broke all of them... I might let them off the hook with a warning. On the other hand, if I don't like someone and they break one minor rule I might use that as an excuse to ban them. Lunar Orbit seems to be having some trouble in deciding whether he is a fair man or not, but this rule, and rule 7 seem to be squarely aimed at just a couple of users. In case I am not around for much longer, I would like to thank those users with whom I have shared courteous, civil and adult debate.
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Post by lordoftherings on Oct 2, 2005 14:15:43 GMT -4
I have heard that there is a video that shows 2 astronauts walking one behind the other, jumping at the same time, each time they move by the same exact distance. Sam Colby says he has seen it only once, and seems that they are abiding by the movement they are forced to do by the wires. Is this true?
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Post by frenat on Oct 2, 2005 14:18:32 GMT -4
Three things of which I'm sure you'll disagree completely then restate your original claim as if nothing happened. 1. The astronaut in the background is moving slower and covering less ground. The skipping gait seems useful for speed but would be overkill if moving slowly. 2. The astronaut in the background appears to be moving uphill. The skipping gait would be less useful while climbing. 3. The astronaut in the background does use the skip from what I can see but not the whole time. But why should he? It's not the only way to get around on the moon. There are plenty of clips of astronauts walking slowly and carefully. You don't always run or always walk or always skip do you? Of course it is hard to see much in these tiny, badly compressed clips that you keep linking to. Lunar Orbit seems to be having some trouble in deciding whether he is a fair man or not, but this rule, and rule 7 seem to be squarely aimed at just a couple of users. In case I am not around for much longer, I would like to thank those users with whom I have shared courteous, civil and adult debate. Of course they are only aimed at a few users! Not everyone on the forum engages in spamming. There are also very few that willfully break rules. Are you trying to imply they are aimed merely at you? Paranoid much matix? Or is it that you've been trying to get yourself banned so you can cry to your friends that we're oppressing the "truth" that you feel it should be aimed at you? As for courteous, civil and adult debate, where has that occurred? I have yet to see that out of you and I'm sure many others will agree. You have been rude, pigheaded, and have lied more than once. I am not the only one that thinks you are trying to get banned. Not a very mature thing to do.
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Post by LunarOrbit on Oct 2, 2005 14:24:20 GMT -4
But look at the rearmost astronaut. He is simply walking, left right, left, right, using exactly the same perambulation as someone moving on Earth. A totally different motion. Why is this? Why is "normal walking" not possible, in your opinion? It might not be the most efficient method of travelling on the Moon, but it's not impossible. Oh, I can be fair but I'm also human. I treat my friends better than I treat people who intentionally try to piss me off. Really only one person seems to be a problem so far. You seem to be incapable of a civil and adult debate. Debating requires communication from both sides and you are only cabable of making claims, not defending them. This is how you debate: You: Wild claim with no evidence Others: Detailed response which thoroughly debunks your claim You: Same wild claim, still no evidence, totally ignoring the responses from the others. That is not how debating works, Margamatix. Whether you stay is up to you. I've posted the guidelines for how you can behave without pissing me off. You know the rules, you don't have to read my mind, so now you have no excuse for your behaviour... you have no one to blame but yourself. You can't say I made a rule up on the spot, you've been warned. Like I said... I will not punish people retroactively. Only your behaviour from this point on will determine whether I ban you or not. But I suspect you want to be banned, so I don't expect you to follow those simple rules I have set. I'm not asking for much, Margamatix...
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Post by ouloncollouphid on Oct 2, 2005 16:35:38 GMT -4
Incidentally, I see that Lunar Orbit has felt fit to introduce a new set of rules, and I reproduce part of them here....... [blah blah blah...] Much amused by the latest instalment in the Margo Martyr Saga. Gosh, Margs, you've really got 'em on the run. They're terrified of you. That can be the only reason that the subject of you getting banned keeps coming up. You're such a free thinker and original mind you're dangerous, dude!
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Oct 2, 2005 19:22:55 GMT -4
I have heard that there is a video that shows 2 astronauts walking one behind the other, jumping at the same time, each time they move by the same exact distance. Sam Colby says he has seen it only once, and seems that they are abiding by the movement they are forced to do by the wires. Is this true? Of course it's not true. First, I'm sure it's an exaggeration to say hop the "same exact distance". Secondly, the astronauts were all similarly sized men, thus it is not at all surprising they would have a stride or hop of similar length. You must realize there are hours of video and thousand of photographs from the moon. If one spends enough time looking over this material they are likely to find a few examples where two astronauts are moving along in apparent synchronization. The fact that Sam Colby has seen it only once is a very strong indication it is only coincidence. If it were due to some sort of rigging with wires then it is likely the same type of rigging would be used elsewhere, in which case we should see many examples.
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Post by JayUtah on Oct 2, 2005 19:41:56 GMT -4
This is generally true of any voluminous body of evidence. You will always be able to find a photo or two, or a few seconds of video, that seem "suspicious" and may seem to support some theory of fabrication. When dealing with explicative hypotheses, one of the tests we commonly apply is a test for limited scope. Theories that explain only one data point in a dataset are not as likely to be correct as a theory that explains many or all elements of the dataset. A theory that works only for two photos out of 20,000 or for ten seconds of video out of dozens of hours commits the fallacy of limited scope.
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Post by sts60 on Oct 2, 2005 20:50:14 GMT -4
They say a picture is worth a thousand words. Are you seriously suggesting that this <LM picture> travelled to the Moon? Yes. It was designed to go to the Moon, and was launched on a rocket that was designed to get it there. The record says it went there. Thousands of people were involved in the effort to make and operate it. All you have done is keep saying a variation on "Can you believe this..." but you have nothing to back your opinion up. We keep asking you to back up your claims, like the LM wouldn't work. The only time you gave a specific reason (the landing load), I immediately showed you that the landing load was well within the design capabilities. Funny, I don't seem to recall your reply to that. Oh, that's right - you never made one. But here you are appealing to ignorance once again ("Are you seriously suggesting..."), attempting to use ridicule instead or rational argument. It won't work here. We're interested in the real world, and in learning things, not in cheap debating tricks. Rest assured, that while you have yet to acknowledge any of the explicit refutations of your claims (CSM couldn't get back from lunar orbit, PLSS couldn't cool suit, the "Type I" fulcrum mistake, the "Saturn V had to be 266 times larger")*, etc., we remember them. You can post all you want about how mean the bullies on apollohoax are being to you, but it doesn't change the fact that you are the one who is pretending that all the times you have been shown wrong - often with explicit calculations - never happened. And you talk about courtesy? * if you're quoting someone else, by posting them here, they're your claims as well
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