To Rise Again Dive Into Outter Space You re My Gravity
It seems like the Cherry-red Bull Stratos spring (redbullstratos.com) is back on track. For those of yous not familiar, the basic thought is fairly simple. Felix Baumgartner will take a balloon ride up to an distance of 120,000 feet then jump out. The project was temporarily on agree due to some legal problems, but it seems to exist settled now.
Yes, I know I have already talked near the Stratos leap many times. Simply that was so, this is now. How nearly I endeavour to answer some of the questions that might come up?
Will he jump from outer space?
I estimate the answer to this question depends on how you define 'outer infinite.' Perhaps the mutual definition is "the region where in that location is no atmosphere." The problem with this is that the Earth's temper doesn't only abruptly cease. The transition from space to the Earth's temper is more like a loma rather than a stride.
If you want some values, well-nigh people consider the International Space Station to be in outer space. This orbits the World at about 300 km to a higher place the surface (or 980,000 feet). You lot could say all the way down to 100 km (330,000 feet) is pretty shut to space. So, 120,000 anxiety isn't quite there. Don't get me wrong. It's still manner up at that place.
Simply what about the density of air that high? On the surface, air has a density around one.2 kg/g3. At 120,000 feet the density is only seven.iii ten ten-4 kg/miii. Since everyone ever loves a graph, here is a plot of the density equally a function of pinnacle (based on this density model).
So, if you wanted to telephone call the jumping meridian "infinite" it wouldn't exist such a terrible affair. You would definitely need a space accommodate that high, so it could exist infinite. Right?
How do yous get to that altitude?
In that location are some options. The first and obvious selection is a rocket. Why not some type of aeroplane? Well, nigh airplanes need this thing called "air" to work. As you can encounter from the previous question, at that place isn't much air up there. And so, other than a rocket, the best selection is a airship. But wait. Didn't I just say at that place isn't much air? Yes, I did. Balloons as well demand air, but if y'all get a big plenty balloon yous can get in work.
If y'all think about the balloon at some detail superlative, the forces on it would exist something similar this.
There is the gravitational force and a forcefulness we similar to telephone call the buoyancy force. Really, the buoyancy force is the result of the air colliding more with the bottom of the airship than information technology does with the top. The bigger the airship, the more than collisions and the greater the buoyancy force. Withal, there is a problem. If you lot but take a balloon and blow it up with air, the gravitational force on the balloon as well increases with the size of the balloon. The fox is to use a gas with a lower density than air. In this instance, that gas is helium.
Still, every bit you can see above, the density of air at 120,000 feet is really depression. With a low density, there not as many collisions between the air and the balloon. The upshot is yous need a bigger airship (which unfortunately has more mass). And so, in the finish, you need a balloon most 80 meters (over 250 feet) across when fully inflated to elevator a jumper and life support capsule to that top.
How much less will the gravity exist at 120,000 feet?
Ok, and so the air is pretty sparse upward there, but what about gravity? Conspicuously there IS gravity in space. This is the force that causes the moon to orbit the World and the Earth to orbit the Dominicus. On a side note, it is fairly common for people to call up in that location ISN'T whatsoever gravity in space.
Anyway, the gravitational force depends on the altitude betwixt the objects (for spherical objects at least). If you lot double the distance between the center of a planet and a spaceship, the gravitational strength volition only be one fourth as much. The key hither is "center of the planet". So, if I am 10 anxiety to a higher place the surface of the Globe and I double this height to 20 feet, how far did I move from the center of the Earth? The answer: not at all (to offset approximation). The reason? The Earth is huge. It has a radius of nearly 6.38 10 10half-dozen meters (or 2.09 10 107 feet).
Go ahead and try this. Put ii.09 x tenvii + 100 in your calculator. What exercise you lot go? You become two.09 ten 10vii. This is because your calculator rounds off the bodily value.
Fine. The gravitational force doesn't change too much virtually the surface of the Earth. Only what about 120,000 anxiety? Well, a i kg mass has a gravitational forcefulness of near 9.viii Newtons (2.two pounds) on the surface of the Earth. At an distance of 120,000 feet the gravitational force would be 9.68 Newtons (2.18 pounds). This 98.viii% the value at the surface. So the answer is that the gravitational forcefulness at 120,000 feet is pretty much the same as on Earth.
Oh, maybe I should add that the gravitational forcefulness on astronauts in the International Infinite Station is nearly 91% the value at the surface. Then why practice astronauts float effectually in space? I am glad you asked (your answer).
What is the speed of sound?
One of the cool things nigh the Red Bull Stratos spring is that information technology will be a run a risk for a falling homo to fall faster than the speed of sound. So, what is the speed of sound? I guess you could ask "what is sound?" - but possibly I will look at that later.
If yous think about introductory physics, the speed of sound is often stated every bit existence around 340 m/due south or 760 mph. This is the value for the speed of sound at normal temperatures and pressures (like near the surface of the Globe). But audio is an interaction betwixt air molecules - so it really depends on what they are doing (and information technology really isn't so unproblematic). Withal, there is i model for the speed of sound that says it is proportional to the temperature (this is merely a model - simply it works fairly well).
The higher you become, the lower the temperature (up to a betoken). Using the aforementioned model for the density of air, I can become the temperature and thus the speed of audio. Here is a plot of speed of sound as a function of altitude.
At 120,000 anxiety the speed of sound is only around 200 yard/s (450 mph).
Can he fall faster than the speed of sound?
Here is the real question that you have been waiting for. The answer is yes (probably). To sympathize how, lets wait at the forces on Felix right later on he leaves the airship.
Since he isn't really moving (however) and there isn't much air anyway, there is just the gravitational force on him. Since this force is down, it causes him to first moving faster and faster as he travels downward.
As he starting going faster, in that location is an air resistance strength. You lot have probably felt this force when you put your hand out of a moving car window. The faster you go, the faster the force. However information technology also depends on the density of air. So, at the begging of the jump, the forces might await like this:
Since in that location is an air resistance force in the opposite direction to the gravitational force, it essentially makes the total force smaller (but still down). This means that he will still speed up, but the charge per unit that he speeds up will be less. The key indicate is that he is Notwithstanding speeding up and getting faster. Oh, this is the part that he could become faster than the speed of audio.
He tin can't go along speed upwards forever. Somewhen, his speed will go large and the density of air will increase equally he gets lower. At some bespeak the air resistance force becomes larger than the gravitational force like this.
Now that the force is in the opposite direction every bit his speed, he slows down. Somewhen, he volition slow down to the indicate where the air resistance strength and the gravitational forcefulness are the aforementioned. At this point, he volition non speed up nor will he tiresome downwardly. This is called concluding velocity.
I am enlightened that I haven't answered the question. What virtually the speed of sound? Honestly, finding the speed isn't quite that easy. Really, the all-time way to exercise a trouble like this is to pause it into a whole bunch of small steps and let a reckoner practise the work.
Doing, that hither is a plot of Felix's speed as a office of fourth dimension. I have included a curve showing the speed of sound for the altitude he is at during that time.
According to my calculation (which does have some assumptions in there) he will be going faster than the local speed of sound for about 1 minute. He volition also go faster than the speed of sound at the surface at one point.
Only don't sky defined autumn around 120 mph?
Sky divers? Yes. Felix? No. Why? Considering as he falls, the density of air (and thus the air resistance) changes. He doesn't stay at the same air density long plenty to slow down to a concluding velocity for the first role of the leap. Of course, eventually he will. Here is a plot of his speed along with the local terminal speed.
You might notice that I cutting off the first part of the graph. This was because the terminal speed at this high altitude was ridiculously big. It made the graph look silly.
That is all the questions for now. I practice have some more Red Balderdash Stratos posts planned.
Source: https://www.wired.com/2012/02/stratos-space-jump-can-you-fall-faster-than-the-speed-of-sound/
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