EPTIf you don't, if i recall correctly it doesn't matter how fast you go, you will never go to space.
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Simberto
Germany11522 Posts
If you don't, if i recall correctly it doesn't matter how fast you go, you will never go to space. | ||
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Acrofales
Spain18006 Posts
On January 11 2018 19:28 Simberto wrote: If you ignore air resistance, you can solve that problem using high school maths and physics. If you don't, if i recall correctly it doesn't matter how fast you go, you will never go to space. Pretty sure if you get launched at lightspeed (as an upper bound) you will go to space even with air resistance. Of course, you will have burned to a crisp LONG before that, but assuming he has a magic space suit that can insulate him from the couple of million degrees he will heat up to, I would like to see the calculations showing he can't travel fast enough to escape earths atmosphere. | ||
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Uldridge
Belgium4800 Posts
On January 11 2018 18:28 Simberto wrote: What do you mean with "spitting stuff out"? Volcanoes? Those have nothing to do with the core, they are purely mantle based. And they don't have a large impact. Woops, I completely forgot about all the layers we have going on lol. Guess I need to revisit basic education.. Are there any interesting interactions going on with the different structures, like pressure exertion / heat exchange between core/mantle so that it can be in a molten state? | ||
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Simberto
Germany11522 Posts
On January 11 2018 20:02 Acrofales wrote: Pretty sure if you get launched at lightspeed (as an upper bound) you will go to space even with air resistance. Of course, you will have burned to a crisp LONG before that, but assuming he has a magic space suit that can insulate him from the couple of million degrees he will heat up to, I would like to see the calculations showing he can't travel fast enough to escape earths atmosphere. Regarding lightspeed: https://what-if.xkcd.com/1/ Regarding the rest, i will have to take a look at it at some point, i distantly kind of recall it not working, but i am uncertain. Maybe it was a different problem with going to space. Edit: come to think of it, it should probably work. Otherwise, stuff like a mass driver launcher would not work at all. No idea what i had been thinking about. | ||
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AbouSV
Germany1278 Posts
If you forget about the air drag, you have your answer, regardless of the angle of the ramp. However, including the air drag, you need enough momentum, to still have the escape velocity when leaving the atmosphere. Let's say you have no significant drag left at around 100km (30 may be enough actually), This would bring us approximately to having the same speed, but a hundred kilometres higher (the escape velocity has dropped by less than a percent by then). My Matlab isn't working here, so I cannot solve the differential equation (there is no analytical solution) to give you a number. The air drag goes with the square of your speed, so the faster you go, the more you have more drag (voluntarily have 'more' twice). The only thing going for you, is that the faster you go, the less time you spend in the atmosphere, and it is actually not so long (a few tens of seconds). To go in this direction, I would recommand using a half pipe to lunch yourself vertically, otherwise you spend more (too much?) time in the atmosphere. | ||
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kidcrash
United States620 Posts
On January 12 2018 04:33 AbouSV wrote: Thank you, the bolded part really puts things into perspective for me. I think subconsciously, my mind picked a 45 degree angle ramp because it's more aesthetically pleasing in my imagination and a half piped seemed to look ridiculous but the whole scenario is ridiculous, so I guess go hard or go home right? I figured it was a little trickier than say, a space shuttle, to calculate because those maintain a sustained speed due to their engines staying on and in this scenario as soon as you leave the ground, you're relying 100% on momentum while fighting the air resistence.If you wanna leave earth (as in go further than the gravitational pull of earth, not just 'into space'), you have to each the escape velocity of earth. At the surface that would be 40 000 km/h, or Mach 30 something. If you forget about the air drag, you have your answer, regardless of the angle of the ramp. However, including the air drag, you need enough momentum, to still have the escape velocity when leaving the atmosphere. Let's say you have no significant drag left at around 100km (30 may be enough actually), This would bring us approximately to having the same speed, but a hundred kilometres higher (the escape velocity has dropped by less than a percent by then). My Matlab isn't working here, so I cannot solve the differential equation (there is no analytical solution) to give you a number. The air drag goes with the square of your speed, so the faster you go, the more you have more drag (voluntarily have 'more' twice). The only thing going for you, is that the faster you go, the less time you spend in the atmosphere, and it is actually not so long (a few tens of seconds). To go in this direction, I would recommand using a half pipe to lunch yourself vertically, otherwise you spend more (too much?) time in the atmosphere. | ||
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kidcrash
United States620 Posts
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ieltsexams11
Australia1 Post
User was banned for this post. | ||
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Korakys
New Zealand272 Posts
On January 11 2018 18:58 kidcrash wrote: Let's say I was on a bike and I was being pulled by a turbo charged speed car with ultra powerful jet propulsion engines. How fast would I have to be going if I let go of the car and launched myself off of a 45 degree angle ramp and i wanted to fly into space. The bike and myself weigh 250 pounds because I have a heavy duty space suit on to stop myself from breaking apart. Edit: im at average sea level for earth whatever that is. 2nd edit: changed the angle of the ramp. I think using a 1km long, 1km tall quarter pipe is reasonable equipment to launch a towed cyclist into space. Also I'm assuming you want to get into space and stay there rather than just pass the Karman line (100km up) and then immediately fall back to Earth. Not taking wind resistance into account you need to be travelling at escape velocity, which is 40,270 km/h. It doesn't actually matter how much your mass is, you just need to get the tow vehicle up to that speed and trust the ramp to convert that fully from horizontal to vertical velocity. Factoring in air resistance is substantially more difficult, but it is a massive effect so it is necessary. I made some very dodgy calculations which lead me to believe you will need to be travelling at about double the escape velocity to overcome the air resistance. That is to say the car should be travelling at about 80,000 km/h (~0.0074% of the speed of light). Even scram jets are not going to cut the mustard; you should investigate nuclear pulse propulsion. Good luck! (I must admit I'm at a bit of a lose as to what you would build the bicycle and spacesuit out of that could survive friction of this magnitude, but, pro-tip: at these speeds you wont have to worry about wheel bearings as you wont need the wheels to turn. Boron nitride perhaps?) Drag equation: www.grc.nasa.gov Coefficient of drag for cyclist: 1.0 (this is in a half-crouch I think). Area of a typical cyclist: 0.4m^2 (again, in the same position). | ||
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Epishade
United States2267 Posts
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AbouSV
Germany1278 Posts
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KR_4EVR
316 Posts
On January 20 2018 05:08 Epishade wrote: Why did the send Matt Damon, a botanist, to Mars without any seeds to plant? Earth isn't the first planet to not have life on it and certainly won't be the last. | ||
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Zambrah
United States7312 Posts
On January 20 2018 05:08 Epishade wrote: Why did the send Matt Damon, a botanist, to Mars without any seeds to plant? Seeds are heavy? | ||
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MyTHicaL
France1070 Posts
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Liquid`Drone
Norway28674 Posts
worked for me! | ||
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Ghostcom
Denmark4782 Posts
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KR_4EVR
316 Posts
On January 23 2018 19:48 MyTHicaL wrote: Does there exist any decent online alarm clock? My phone died and I woke up this morning feeling much better than I normally do, just to discover that I managed to sleep through a solid 4 hours of class, yey. -_-;:. It's called a wrist-watch. Battery will last you for 10 years. It may not be online in the conventional sense, but it has zero downtime and never gets lost! | ||
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KR_4EVR
316 Posts
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farvacola
United States18828 Posts
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Danglars
United States12133 Posts
On January 24 2018 09:24 KR_4EVR wrote: It's called a wrist-watch. Battery will last you for 10 years. It may not be online in the conventional sense, but it has zero downtime and never gets lost! Some of those suckers aren't very loud if you're a sound sleeper. Like, forget about it if your arm is under blankets. A dedicated alarm clock--now that's the stuff. | ||
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