skymama 37 #1 July 3, 2002 I saw a little blip on Cheryl Stearns on the national news last night (go Cheryl!). On the program, it said she would jump 24 miles above the earth and go 800-900 mph. My question is, just what is going to make her go so fast? The guys who do the speed jumping only go somewhere between 200-300, right? Doesn't something that doesn't have an engine max out at some point in it's speed while it is falling? She's really going to go 500 mph faster than the guys who are really trying to go fast? And, how is her body going to be able to withstand that speed for 24 miles? I'm really bad at science, so if you can explain this to me, please use small words that are in the normal English vocabulary.She is Da Man, and you better not mess with Da Man, because she will lay some keepdown on you faster than, well, really fast. ~Billvon Quote Share this post Link to post Share on other sites
skybytch 273 #2 July 3, 2002 She's gunning for Joe Kittinger's record freefall. The atmosphere is a lot thinner up where she's planning to exit, which means faster speeds in freefall. She'll be wearing a pressure suit to keep her alive. See here - http://www.stratoquest.com/ for all the details. Quote Share this post Link to post Share on other sites scottbre 0 #3 July 3, 2002 Let's see if I can beat the likes of billvon and quade to the answer on this one. Because she will be jumping from so high, there is significantly less air at that altitude (one of the reasons why she will be wearing a space suit). Since there is less air, there is less resistance to counter the effects of gravity. This results in her falling much faster during the first half of her dive. As she gets closer to earth the amount of air hitting her will increase which will slow her down to close to the regular skydiver terminal velocity. Damn you skybytch. Beat me. "Your mother's full of stupidjuice!" My Art Project Quote Share this post Link to post Share on other sites wildblue 7 #4 July 3, 2002 over-simplified answered = the air is thinner, less "stuff" to cause friction, go faster.it's like incest - you're substituting convenience for quality Quote Share this post Link to post Share on other sites ltdiver 3 #5 July 3, 2002 Andrea, Have to run to work right now, but here's a start for you today on this... See: http://www.stratoquest.com/ ltdiver Don't tell me the sky's the limit when there are footprints on the moon Quote Share this post Link to post Share on other sites wildblue 7 #6 July 3, 2002 Quote(one of the reasons why she will be wearing a space suit). The other being something about she could freeze to death as her blood boiled?it's like incest - you're substituting convenience for quality Quote Share this post Link to post Share on other sites jfields 0 #7 July 3, 2002 Skymama, The difference is the density of the air. At the higher altitudes she plans to jump from, the air is much, much thinner. And it is the air resistance that sets what terminal velocity is for any given object. The closer to the ground something is, the higher the density of the air, and the more the resistance. We would basically just keep accelerating if we didn't reach an equilibrium between the effect of gravity and the resistance of the air. That is why "terminal velocity" is different for flat, sit and head-down. Flat flying has more wind resistance than sit, which has more than head down. So the equilibrium points are different for each of them. This is sort of simplified. Does it make sense? Quote Share this post Link to post Share on other sites skymama 37 #8 July 3, 2002 Thanks for your replies, you all are QUICK! Justin, your description of terminal velocity was exactly what I was trying to grasp. You did good!She is Da Man, and you better not mess with Da Man, because she will lay some keepdown on you faster than, well, really fast. ~Billvon Quote Share this post Link to post Share on other sites jfields 0 #9 July 3, 2002 QuoteJustin, your description of terminal velocity was exactly what I was trying to grasp. You did good! Thanks! Want me to teach you about friction and surface tension? Quote Share this post Link to post Share on other sites billvon 3,107 #10 July 3, 2002 >The other being something about she could freeze to death >as her blood boiled? Both dangers are overrated. You would not likely freeze to death in a near-vacuum - it's a great insulator, and astronauts usually have a much bigger problem being too warm than too cold, since you have to radiate away the heat instead of conduct it away. (Or you have to heat up some other subtance and exhaust it.) And while the boiling point of water is indeed below 98 degrees at the altitudes she will be at, hypoxia becomes a problem well before water phase change. Since phase change takes a lot of energy, hypoxia is a much bigger problem. To put it in colloquial terms, you don't explode when exposed to vacuum. Interestingly, she could do the jump with nothing more than a tight jumpsuit if she wanted to. It would have to be very tight - she would need an average pressure on her body of about 100-150mmHg or 2-3 PSI to prevent bruising and to allow her to breathe air of sufficient pressure. Quote Share this post Link to post Share on other sites quade 4 #11 July 3, 2002 QuoteLet's see if I can beat the likes of billvon and quade to the answer on this one. Pretty safe bet if somebody asks a question before 9:30 on a weekeday. quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. Reply to this topic... × Pasted as rich text. Paste as plain text instead Only 75 emoji are allowed. × Your link has been automatically embedded. Display as a link instead × Your previous content has been restored. Clear editor × You cannot paste images directly. Upload or insert images from URL. Insert image from URL × Desktop Tablet Phone Submit Reply 0
scottbre 0 #3 July 3, 2002 Let's see if I can beat the likes of billvon and quade to the answer on this one. Because she will be jumping from so high, there is significantly less air at that altitude (one of the reasons why she will be wearing a space suit). Since there is less air, there is less resistance to counter the effects of gravity. This results in her falling much faster during the first half of her dive. As she gets closer to earth the amount of air hitting her will increase which will slow her down to close to the regular skydiver terminal velocity. Damn you skybytch. Beat me. "Your mother's full of stupidjuice!" My Art Project Quote Share this post Link to post Share on other sites
wildblue 7 #4 July 3, 2002 over-simplified answered = the air is thinner, less "stuff" to cause friction, go faster.it's like incest - you're substituting convenience for quality Quote Share this post Link to post Share on other sites
ltdiver 3 #5 July 3, 2002 Andrea, Have to run to work right now, but here's a start for you today on this... See: http://www.stratoquest.com/ ltdiver Don't tell me the sky's the limit when there are footprints on the moon Quote Share this post Link to post Share on other sites
wildblue 7 #6 July 3, 2002 Quote(one of the reasons why she will be wearing a space suit). The other being something about she could freeze to death as her blood boiled?it's like incest - you're substituting convenience for quality Quote Share this post Link to post Share on other sites
jfields 0 #7 July 3, 2002 Skymama, The difference is the density of the air. At the higher altitudes she plans to jump from, the air is much, much thinner. And it is the air resistance that sets what terminal velocity is for any given object. The closer to the ground something is, the higher the density of the air, and the more the resistance. We would basically just keep accelerating if we didn't reach an equilibrium between the effect of gravity and the resistance of the air. That is why "terminal velocity" is different for flat, sit and head-down. Flat flying has more wind resistance than sit, which has more than head down. So the equilibrium points are different for each of them. This is sort of simplified. Does it make sense? Quote Share this post Link to post Share on other sites
skymama 37 #8 July 3, 2002 Thanks for your replies, you all are QUICK! Justin, your description of terminal velocity was exactly what I was trying to grasp. You did good!She is Da Man, and you better not mess with Da Man, because she will lay some keepdown on you faster than, well, really fast. ~Billvon Quote Share this post Link to post Share on other sites
jfields 0 #9 July 3, 2002 QuoteJustin, your description of terminal velocity was exactly what I was trying to grasp. You did good! Thanks! Want me to teach you about friction and surface tension? Quote Share this post Link to post Share on other sites
billvon 3,107 #10 July 3, 2002 >The other being something about she could freeze to death >as her blood boiled? Both dangers are overrated. You would not likely freeze to death in a near-vacuum - it's a great insulator, and astronauts usually have a much bigger problem being too warm than too cold, since you have to radiate away the heat instead of conduct it away. (Or you have to heat up some other subtance and exhaust it.) And while the boiling point of water is indeed below 98 degrees at the altitudes she will be at, hypoxia becomes a problem well before water phase change. Since phase change takes a lot of energy, hypoxia is a much bigger problem. To put it in colloquial terms, you don't explode when exposed to vacuum. Interestingly, she could do the jump with nothing more than a tight jumpsuit if she wanted to. It would have to be very tight - she would need an average pressure on her body of about 100-150mmHg or 2-3 PSI to prevent bruising and to allow her to breathe air of sufficient pressure. Quote Share this post Link to post Share on other sites
quade 4 #11 July 3, 2002 QuoteLet's see if I can beat the likes of billvon and quade to the answer on this one. Pretty safe bet if somebody asks a question before 9:30 on a weekeday. quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
