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Post by the light works on Oct 11, 2015 15:48:02 GMT
Ok, so, try the following, throw up in a respirator and sneeze in a helmet. You can hold your breath until you stop.... You cant "wipe" the inside of a visor at 80mph............. but you can open the visor right where you are. (and no, I haven't thrown up in a respirator, either, and have very sincere plans not to. I believe I have sneezed in a helmet, and I KNOW I've sneezed in a SCUBA mask.) |
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Post by silverdragon on Oct 11, 2015 15:51:25 GMT
You can open your visor at 80-mph in rain can you?.. and SEE where you are going?...
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Post by the light works on Oct 11, 2015 16:02:54 GMT
You can open your visor at 80-mph in rain can you?.. and SEE where you are going?... easier than I can pull off my mask in a fire. not that I really want to do either one. |
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Post by tom1b on Oct 12, 2015 3:49:59 GMT
The dust storm is listed as the biggest inaccuracy in movie, since it is the cause of his being stranded. No Wind Chill on Mars"But air that thin doesn’t do a good job of carrying heat away, even when the winds are blowing at 100 kilometers per hour (as they sometimes do in the Red Planet’s global dust storms). In other words, he notes, on Mars the wind chill—the added cooling effect generated by air sweeping heat away from a body warmer than its environment—is almost nonexistent." How did 'The Martian' do on the science of Mars weather?"The fact is that while Mars winds can build up significant speed, the atmosphere is so thin - 0.6 per cent of Earth's atmosphere - that even the fastest winds there carry very little force with them. With the density of Mars' surface air, a 75 mph wind gust would have the same "push" as an 8 mph wind here on Earth, which is considered a "gentle breeze" by meteorological standards. The strongest of these winds are enough to cause dust storms, and some that can reach global scale, but they wouldn't cause the storm witnessed in the movie." How Accurate Is The Martian? 9 Things The Movie Got Right And Wrong"Let’s get the big one out of the way nice and early: The dust storm that sets everything in motion at the start of the movie is not accurate. Although Mars does get dust storms, the atmospheric pressure is so low that the wind is negligible, although the dust itself can be harmful." " 'Dust storms certainly do occur on Mars, they get winds in excess of 100 mph (160 km/h),' Dave Lavery, Program Executive for Solar System Exploration at NASA headquarters and a consultant for the film, told IFLScience. 'But a 100 mph wind on Mars, because the atmosphere is so thin, has the same inertia and dynamic pressure down at the surface as about an 11 mph (18 km/h) wind on Earth. It’s not going to have the sort of energy to move large objects the way that is portrayed in the book and the film.' To be fair, Andy Weir readily admits the dust storm was used simply to move the plot along and leave Mark Watney stranded on Mars." |
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Post by rmc on Oct 12, 2015 14:00:53 GMT
Good research, tom1b! Guess that's that! Not too much wind force after all. But what about repairing the habitat with a plastic sheet duct tape and cinch strap? The way depicted in the movie, it looked a bit sloppy. Wouldn't his method end up leaking enough to be a strain on oxygen resources?
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Post by Cybermortis on Oct 13, 2015 22:43:15 GMT
You are missing that; Wind storms on Mars will contain a vast amount of dust and probably small rocks. So objects are not just dealing with the force of the wind but also the impact of that dust and rocks.
The surface area of an object will affect how much force wind will impart on that object - which is why a 400 mile per hour wind would flatten your house but not rip the winds off a 747. In this case it is likely that a strong wind on Mars would rip a communications dish out of the ground (or off its mounting) before it tore a flag pole out, assuming both were firmly secured in the first place. The dish has a considerably larger surface area than a pole. And the pole is probably a single structure and not relying on any connections to what is pushed into the ground.
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Post by rmc on Oct 14, 2015 2:10:46 GMT
Vast amount of tiny, tiny talc-like particles. As stated previously, the force of a 60 mph wind on Mars equates to that of an 11 mph wind on Earth. 11 mph wind on earth could create a dust storm too, so long as the finest of fine partcles are available. So, with such fine particles adrift only, there are no rocks or even pebbles flying.
Also, as to the dish, even if the dish were extremely light, in order to accommodate getting it from Earth to Mars economically, there is little likelihood an 11 mph wind would 'inflate' it and accelerate it such that it would be forced into a reasonably-massive person so that it sends him flying 20 or 30 feet, even at 1/3rd or 2/5ths his Earthbound weight.
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Post by silverdragon on Oct 14, 2015 7:59:37 GMT
Are you thinking of earth density wind forces.
The density of Martian winds is only 1:100 of earth....
With less density, all objects with mass have less force affecting them, so even at high speed wind, there is less air friction that would move the objects.
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Post by the light works on Oct 14, 2015 13:39:17 GMT
Are you thinking of earth density wind forces. The density of Martian winds is only 1:100 of earth.... With less density, all objects with mass have less force affecting them, so even at high speed wind, there is less air friction that would move the objects. however, I think the theory question is that the wind driven objects will still develop the velocity and have the mass, even if there is less air friction moving them. so even if the air movement only has the force of an 11 MPH breeze on earth, you still have a cloud of dust going 100MPH. - and my understanding of the question is to ask whether the 100MPH on mars = 11 MPH on earth is including windborne dust. |
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Post by rmc on Oct 15, 2015 1:41:57 GMT
So, if the particles do reach velocities of 60 mph or 100 mph, and if there are enough of them, it is their mass and not necessarily the mass of the wind itself that imparts the force necessary to do the work seen.
Interesting.
Would a vaccum tunnel with a blast of dust through it suffice for force testing, if the dust reproduces similar work on some similarly massive object?
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Post by the light works on Oct 15, 2015 2:06:43 GMT
So, if the particles do reach velocities of 60 mph or 100 mph, and if there are enough of them, it is their mass and not necessarily the mass of the wind itself that imparts the force necessary to do the work seen. Interesting. Would a vaccum tunnel with a blast of dust through it suffice for force testing, if the dust reproduces similar work on some similarly massive object? it would be interesting to find out the result. |
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Post by silverdragon on Oct 15, 2015 5:56:08 GMT
I was going to say something about gravity, but decided against it?...
Dust storm in a vacuum... sound a good idea.
Even at earth's gravity, if you could get a decent dust storm going in a 1:10th earth's atmosphere density, I think it would be a pretty good indication. If that can be then further done at a 1:100 density, even better.
Then go the other way, in a pressure vessel, and see what a 100:1 density would do as well?...
It would also answer why dust storms on earth do not send debris flying off into space... once it gets up there into the atmospheric conditions of near space, it looses all force from winds pushing it, and gravity takes over again, so dust just sinks back down again?...
This is why I love this place, we get an idea, take it to its illogical conclusion, come back to reality, and then go suggest some bloody good ideas for testing.
Whilst we are at it, we can look at if a small storm that does get airborne particles, being there would be less air friction, would the particles fly further anyway.
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Post by silverdragon on Oct 15, 2015 6:00:38 GMT
Getting a decent wind up on a lower density atmosphere....
It needs asking.
Would you have to change the size of the fan blades.
I am guessing the answer would be yes you would....
We think of the fan blades on earth as working to the conditions we have.
A small motor with small fans would over-rotate in a less dense atmosphere, less air friction, maybe even burn out under the lower load....
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Post by the light works on Oct 15, 2015 11:07:51 GMT
maybe the build team should get back together and pitch a show about answering obscure science questions.
as for the fan motor, it depends on the motor. some motors can run with zero load forever, but with less air density, the motor might overheat for lack of cooling.
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Post by rmc on Oct 15, 2015 14:09:53 GMT
Picture a small-scale vacuum chamber with an electromagnet on one side and a pile of very fine iron rust (dust) on the other that includes an umbrella-like object between. Flip a switch and a predetermined quantity of fine iron dust is accelerated toward the open umbrella-like object. In this case, there is no air. So, we are just looking at how a finely-distributed array of mass, spread out over a given volume can impart force on a standing object. We are still at Earth's gravity with this, so the friction forces holding the object in place on the ground (traction) are different than such forces on Mars. So, the resulting acceleration should be recalculated to account for the weaker traction of the object on Mars. Or, drop the chamber like an elevator once the electromagnet is enabled. Or, hang the umbrella-like object from wires. Question: what speed does an electromagnet impart on such dust? Can the distance between magnet and dust be adjusted to best replicate 60 mph, or 100 mph? Keeping in mind that replicating Martian atmosphere is possible in this sort of chamber too, but any air would not get accelerated by the electromagnet means suggested here. Would complicating the chamber with a light atmosphere and fan help or hinder such an experiment?
One other question: If Mars's wind is a constant 60 mph, would that certainly accelerate a small dust particle to 60 mph? Is Mars's wind constant enough to do that?
Forgot: Actual iron rust, though fine at times, isn't really magnetic due to oxygen and electron reconfiguration. Maybe there is a dust made from iron itself that would be fine enough? Although it would be pretty dense. Also, the idea of just using a fan in thin atmosphere allows us to see if regular dust is accelerated properly and allows us to use less dense dust particles. I guess I retract my electromagnet accelerator idea.
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Post by the light works on Oct 15, 2015 14:58:14 GMT
Picture a small-scale vacuum chamber with an electro magnet on one side and a pile of very fine iron rust (dust) on the other that includes an umbrella-like object between. Flip a switch and a predetermined quantity of fine iron dust is accelerated toward the open umbrella-like object. In this case, there is no air. So, we are just looking at how a finely-distributed array of mass, spread out over a given volume can impart force on a standing object. We are still at Earth's gravity with this, so the friction forces holding the object in place on the ground (traction) are different than such forces on Mars. So, the resulting acceleration should be recalculated to account for the weaker traction of the object on Mars. Or, drop the chamber like an elevator once the electromagnet is enabled. Or, hang the umbrella-like object from wires. Question: what speed does an electromagnet impart on such dust? Can the distance between magnet and dust be adjusted to best replicate 60 mph, or 100 mph? Keeping in mind that replacating Martian atmosphere is possible in this sort of chamber too, but any air would not get accelerated by the electromagnet means suggested here. Would complicating the chamber with a light atmosphere and fan help or hinder such an experiment? One other question: If Mars's wind is a constant 60 mph, would that certainly accelerate a small dust particle to 60 mph? Is Mars's wind constant enough to do that? Forgot: Actual iron rust, though fine at times, isn't really magnetic due to oxygen and electron reconfiguration. Maybe there is a dust made from iron itself that would be fine enough? Although it would be pretty dense. Also, the idea of just using a fan in thin atmosphere allows us to see if regular dust is acelerated properly and allows us to use less dense dust particles. I guess I retract my electromagnet accelerator idea. the magnet idea is a good idea, I think. it will definitely measure the degree to which airborne material can change the equation. maybe hematite dust would be a good powder. |
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Post by rmc on Oct 15, 2015 15:33:02 GMT
Seems as though determining the actual amount of mass that Martian high-speed winds can carry for a given volume of air-mass is a vital part of this problem though (and the actual velocity of both the wind and the particle mass). Also seems once that is obtained it reduces back to potential energy and momentum type of problem, like one of these for instance: titan.bloomfield.edu/facstaff/dnicolai/images/ImagesPhy-105/lesson65.jpgWhere the bullet shown would actually be the array of ferromagnetic dust, and the block on hinge-like wires would be the umbrella-like object intended. |
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Post by the light works on Oct 15, 2015 18:50:31 GMT
Seems as though determining the actual amount of mass that Martian high-speed winds can carry for a given volume of air-mass is a vital part of this problem though (and the actual velocity of both the wind and the particle mass). Also seems once that is obtained it reduces back to potential energy and momentum type of problem, like one of these for instance: titan.bloomfield.edu/facstaff/dnicolai/images/ImagesPhy-105/lesson65.jpgWhere the bullet shown would actually be the array of ferromagnetic dust, and the block on hinge-like wires would be the umbrella-like object intended. yep, it is definitely an interesting puzzle. way beyond my abilities, but interesting. |
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Post by Cybermortis on Oct 15, 2015 19:48:22 GMT
*Coughs*
Could someone explain how you'd get a fan to move air in a vacuum?
Dust storms do exist on Mars, and regardless of the actual size of the particles or their speed (which would have to be high enough to keep them airborne anyway) the impact of those particles would significantly increase the amount of force on any object they impacted.
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Post by the light works on Oct 15, 2015 19:51:48 GMT
*Coughs* Could someone explain how you'd get a fan to move air in a vacuum? Dust storms do exist on Mars, and regardless of the actual size of the particles or their speed (which would have to be high enough to keep them airborne anyway) the impact of those particles would significantly increase the amount of force on any object they impacted. partial vacuum to match martian atmosphere. not hard vacuum. |
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