FINAL SCIENCE CLASS- How to Survive a 5 Mile Fall with No Parachute

[Music] welcome back to the final science class we are live this is exciting the way this works is you should know by now as we start with the question and then we have three clues to help answer that question today's question is how do you survive a five-mile fall with no parachute and there's so much juicy science packed up into this so we're going to get right into this first a very quick announcement as to why this is my last class because a lot of people have asked and I would say for starters I wanted to do this class if we were lined for three reasons one teaching high school physics is my dream job so I wanted to try it out and see if it really was cool the second is it gave me a chance for some mastery learning I gave a TED talk on the SuperMario effect I'm like I'm just gonna try this I'm a totally fail but it'll be fun to get a little bit better and then the third is I didn't want to be completely absent during this whole thing so just a way to be a little bit more present so addressing those three things basically I've loved it it's been really fun I still want to teach even more so now the second thing I've learned a bunch hopefully you look at the first class versus this class this one should be a little bit smoother I feel like I've learned a lot and then three things have stabilized a little bit with this whole crazy coronavirus situation so I feel a little bit more comfortable pulling back so why not keep doing it the biggest thing is it just takes a lot of time I want to do it right I want to give you guys something good I'm still making my monthly videos I've been getting up at 6 a.m. for the past two weeks working on this next video which is gonna be really crazy and fun and then it's just kind of like it's given me a new opportunity from teaching this class there's an opportunity I'm now working on in the background that has to do with teaching that all will be coming in the future at some point that you guys will be available to you guys and then the final thing is this has sort of been a bummer with the corona virus but the positive thing is my schedule is cleared and I really have enjoyed running time with my family and I didn't want this to be a situation where it just came and went and I just felt like I packed my schedule with stuff like I usually do I really want to take advantage of this so to be fair to my family and to me and I'm really enjoying it I just kind of want to pull back a little bit but I'm doing great mental health a lot of people are like are you okay yes I'm great I'm doing all the things as much as possible to keep both my physical and mental health in a good spot and I really hope you guys are too that's really important you got to hang in there we can do this okay on to some science how do you survive a five-mile fall with no parachute I'm going to start with the riddle you're an astronaut congratulations I can do that I worked for NASA so I can just grant that you're an astronaut you're on the internal space station something needs to be fixed someone hands you this hammer you go out there you're fixing it suddenly you realize you forgot to tie your cable to the space station and you're slowly drifting away what should you do and if you're like oh you should just do one of these things where you swim back to the space station that won't work and let me show you why this is an astronaut they've got him right in the middle and your center of mass it does not move you have absolutely nothing to push against you can't do anything it's like being in the middle of a frozen lake right no matter what he tries there's nothing he could do he could barely push against the air molecules which is like what he's trying to do but if you were actually outside the space station you wouldn't be able to do that so remember you're holding this wrench and so holding this wrench what can you do maybe you figure it out already you want to throw it in the opposite direction why do you want to do that well our buddy Newton came up with the law about this Newton's third law equal and opposite reactions so by throwing the wrench this way that's gonna make you go back this way now the wrench will be going fast because it weighs less and you'll move back a little bit slower but you actually will move back which is why having a gun in space is actually of useful there are oxidizer so it will fire and you fire it you'll go the opposite direction so if you wanted to go that way on the moon you just like fire that way you're like you just fly up so well a few weeks ago we talked about inertia which is like how much stuff a thing has right how hard it is to move a thing so momentum is just that inertia in action that gives us our first clue maybe you've heard of this word before momentum oh yeah I gotta throw this momentum mass times velocity okay it's like inertia mass velocity movin so there's this thing called conservation of momentum which is really helpful that's what's happening with the wrench and space momentum of that system is conserved so by definition if you throw this and you gotta move that back move back that way so they kind of cancel each other out this is true even with let's say you on the earth you're like yeah mark if I jump up technically if I hit the ground the earth should move down a little bit if momentum is truly concerned and here's what's wild it actually does the earth moves the thing is is you were such a tiny wrench compared to this big mass of Earth it throws goes that way and it does move ever so slightly the other direction so this is a true law that holds true everywhere now where else is this used balloons you've blown one of these up before so you should know very well what's gonna happen if I let this go I'm gonna do my best to hit the camera I was before a job Oh balloon you have a list pressure it's pushing air molecules out that way and so by definition hammer out the back the balloon conservation conservation momentum has to go the other way this is how Rockets work you can't use a propeller in space there's nothing to push against so rockets are literally throwing hammers out in the back of a rocket and that makes the rocket go in the other direction of course there it's a chemical combustion and you have gases that are expanding and moving out that way and by definition the Rockets gotta go the other way so there's even an engine and by the way in a second we're gonna get to this thing where I'm breaking all these glasses with the co2 cartridge right after this next stop we're gonna do that which is probably gonna be a bad idea but we're gonna try it anyways they even have ion engines and ion engines are something we use in space you're freakin throwing electrons they don't weigh very much but you have so many and you're putting them out so fast because of conservation momentum it moves this thing forward some of our farthest space path spacecraft like dawn are being propelled by ion engines it's literally electrons being shot out now do you know the farthest object man-made object in the whole solar system it's actually something called Voyager this came from JPL it is 13 million miles away and if you're like me 13 million miles doesn't mean it's moving 11 miles per second by the way just fast think of something 11 miles away in a second it moves that fast it's the farthest man-made object ever to help you get a sense of scale of what that means if the Sun were a soccer ball like this and the earth were a BB and that is the correct scale how far out do you think the earth orbits around that Sun I asked a bunch of people this question and in general I got answers about like this or this maybe some like this it's not their fault because that's kind of how they're drawn on these scales of a solar system so I actually did a video about this I'm gonna show you a clip from this video to help us appreciate how far away voyager is so if you retain nothing else from this video just remember that earth is the head of a pin and it's at the 26-yard line [Music] and as the final rocky planet we have Mars at the 40-yard line also a pleco pepper and now we start to see bigger gaps and more than a football field away from our Sun we have Jupiter which is the scaled size of a grape so then eventually I kind of summarize I went through all the planets with scales here's the summary which is also the sizes of Neptune and orbits around our Sun the size of a soccer ball nearly eight football field so there in the distance you can see the soccer for this view should help you appreciate the difficulty in accurately representing both the size and distance between the planets in a single image okay so before we get to the new ninth planet let's recap so we've got a pepper flake at the 10-yard line for mercury and then a pinhead at the 18-yard line for Venus and then another pinhead for Earth at the 26-yard line and then a pepper flake for Mars at about the 40 and then of course the asteroid belt and then we make it to Jupiter which is a grape at about 135 yards then we cross the street to get to Saturn which is a grape that orbits at about two and a half football fields around our soccer ball Sun then we double our distance from the Sun to get to the seventh planet which is a pea at five football fields away and finally at nearly eight football fields away from our Sun we have another P which is Neptune [Music] and now we've laid the framework for understand so that Voyager spacecraft I told you about which is using normal proportion its propulsion it's not actually using ion engines but the point is it's really far away it is you see this distance here it's five times the distance of Neptune to the Sun so on this scale it's like two and a half miles away five times this gap right here is how far we've sent it and what's so cool about it this is a picture of it when it was flying by Jupiter obviously an artist rendition this was made at JPL which is really cool on it we have something called the Golden Record and on that it has instructions on how to play this record there's a needle enclosed in this here's directions to where we are in our solar system it has some basic information about atoms and then on the back it has sounds of the earth and in here you could decode it and there's pictures of the earth has music it's really cool Carl Sagan had this to say he said the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet if you need a good science hero Carl Sagan's your guy what's also cool about that is even at the speed it's traveling at 11 miles a second it'll take 40,000 years before that little message in the bottle is to our nearest neighbor so 40,000 years from now someone may find that and be like wow this is so cool it's a record of our civilization no matter what happens here okay let's do something super not advised in a live class let me tell you the setup we've got here things are about to get real this is a co2 cartridge I've got a it goes on this little track right here we've put a nail on the front it's gonna hit these glasses we're gonna see how many glasses we could break and at the back we've got duct tape kilt Ken here he's got the view of the house he's coming back for a guest appearance in the last one now why am I doing this well this is jet propulsion this rocketry this is conservation of momentum there's all this pressurized gas in here it's gonna shoot out the back hammers in space right it's gonna throw some hammers we're just going to move this in the opposite direction potentially very quickly because it's lightweight compared to all the particles that it's going to be shooting out with the pressurized air okay so so much could go wrong here let's just see what we can do all right so I'm gonna count down three two one then I'm gonna hit this little nail which should puncture the back of the co2 cartridge and send it that way I might flinch we'll see okay here we go three two one I'm terrified that didn't work okay sometimes it takes a couple tries here we go three two one all right again it's sort of bit my nail hold on check the alignment okay I just need to hit it harder I think okay try it one more time three two one give me another nail all right I do have footage from this morning when we tried this out do we have the replacement now we don't have a replacement nail okay where did I just throw that one I will show the footage let me try we're gonna try it once more with this current nail hold on okay all right I'm not giving up okay line it up here we go I'm really gonna go for it now three two one oh we actually did puncture the back it must be a bad cartridge huh do you give me a new one we'll get this if you have a new cartridge here we'll try it once more I'll try it this one just wasn't full so I was concerned that maybe they were old alright here we go we're gonna give it over try otherwise I'll show you the video of how we did it this morning let's see if I can puncture this kind of bent the nail alright well here's what we're gonna do we're gonna move this out of the way we might try bringing it back at the very end I'm gonna have my buddy Josh here try and fix it and we'll see if maybe at the end we could get it going in the meantime I will show you what happened and the face of my reaction when we tried it this morning here we go let's see actually not this one right here this is science okay a punctured and the reaction so like I said it can be dangerous we did modify the system so this is what we changed it to here we go is there sound Alex so that could be what happened we made some changes to make it go even faster which hopefully will really show right in the very end but okay here we go we're live well that's actually probably not such a bad thing because it was gonna make a lot of glass so if all the glass comes at the end that may work better okay so you have this momentum right something's moving fast how do you stop it or even get it going now that's a fancy word oops that's a fancy word called impulse impulse is Force Times time or it's it's the change in momentum basically right now that's gonna sound a little fancy don't worry about that here's here's the demo we're gonna do now we're gonna bring this sheet in if you can help us out Josh I've got an egg here right and I'm gonna try two things one I'm gonna throw this egg against this wall and then after that I'm gonna strode it gets the sheet and I want you a different egg because foreshadowing it may not survive the wall in physics terms I want you to tell me the difference between these two things okay you ready here we go now make a hypothesis on what's about to happen I can throw this in maybe 30 miles an hour here we go it broke okay keep that in your brain we're gonna do another one right here here we go I'm gonna move this here okay all right I'm gonna get another egg clearly this isn't a different egg all right you can see me here we go I'm gonna throw it right here same speed okay didn't break physics all right help me move this out Josh and you're kind of like all right big whoop and I threw that pretty hard I could throw that as hard as I want it wouldn't break in the sheet in physics terms what do you think is the difference between those two it's the same speed well the difference is in one the time was very short against the wall whereas in the other one the time was big and therefore the force was small these are indirectly proportional turns so if one goes big the others got to go small if one goes small the others got to go big in the case of the egg hitting the wall what was small the thing that was small was my time and therefore force had to be big in the case of the sheet the thing that was big longer was the time therefore the force was smaller here's another way to think about this you can see right here I've got this little stick let's say that represents the force of the molecules holding this egg shell together right this is the impulse the total number of blocks can't change it's the same at any point if you spike above this line the molecules that the force is holding out of the eggshell you're gonna break the eggshell okay but what you can do is if you can flatten the curve along this axis is time if I can take I take those same amount of blocks I can't get rid of blocks but I can take them if I rearrange them so now the event just takes longer look what happens I'm underneath this line now right I stay beneath that curve I flatten to the curve and as a result the egg survives there's no moment where it spikes up and gets bigger okay we're kind of narrowing in on what the answer is so then why the heck do we have airbags and cars right keep this in mind what do airbags and cars do well they extend to the top it takes for you to stop as opposed to hitting the steering we're really fast therefore what happens longer time you flatten the curve you stretch this out the force is gonna be less right where else do you see this long jumpers when they're jumping do they land in asphalt no what do they land in sand well what's the deal with sand well all sand does is it lengthens the time stretches it out of the event the change of momentum the impulse to happen to go from moving fast to stopped right how about with your phone even the difference of dropping your phone unlike a wooden floor versus a marble floor which is gonna break more well going back to this right here this is the the strength of your iPhone of the phone's glass holding it together on marble you're just gonna get this spike it's gonna it's gonna happen shorter because it's harder whereas even wood floor which seems pretty hard it's enough of a difference fractions of a millisecond that keep it below the line and it won't break parkour right people do parkour they jump off crazy things what do they do they roll what does rolling do well that extends the time for which you stop versus just stopping yourself in fact if you bend your knees versus locking your knees it's like 10 to 20 times less force just by bending your knees jumping off something versus keeping them locked check out this clip right here of this guy jumping off this roof that seems insane right thinking about it you see here he ripped his pants a little bit but what was the trick to making that happen time he slid down the roof which allowed him to lengthen the time for the event to occur even cars they used the thought was like oh we should make these as strong as rigid as possible really rigid like steel don't bend at all turns out that's the wrong thing because the time is then short and it's like you hit really hard now cars are designed to actually crumple they crumple and crush all it's doing extending the time and as a result so many more people lived through car accidents than they used to okay what about this principle in the opposite where's the case where you might want to have a high force how about with karate' if you're breaking a wood board this is why you shouldn't chicken out if you're trying to break a wood board and you should follow through because you want to hit this spike as quickly as possible because if you do that and you break the board there's nothing left you actually get a cheat and not have these there you have a momentarily you know it hurts your hand just for a second but once you break it there's nothing left right the worst thing you can do in that situation is chicken out so you get right up to this line and then you stay underneath it because then it's like oh all that energy is going to your hand where if you do just committed to it you could really quickly broken it and be done with it another example here's a rubber hammer versus a metal hammer and you wouldn't think it makes such a big difference but this is more effective at hammering in nails except from in the case mine because it's harder so it's a shorter time bigger force you want to use the rubber nail if you don't want to like damage something as little as that seems to make a difference that tiny little difference in stiffness means that the length is just a little bit longer what if you want to increase your momentum right so let's say you're hunting or whatever a bow and arrow target if you pull it back just a little bit you really want the more time as possible Force Times time equals your change in momentum that's why pulling it back is better you have more time for it to be under force of the string you're gonna have more momentum for your arrow same with like a gun a longer barrel means it will go faster because it just has more time to be under the force of the gasses coming out and a rifle goes faster than a handgun yeah also with sports golf tennis whatever the reason you follow through is you want to extend the time you have against the force so anyways I could go on but the point is I love this when one little nugget one little equation just one little you know mental model to have in your brain can explain so many things in the real world so clue 3 it's all about time and that's what I want you to remember this right it's about the time it takes for the event to be slowed down is proportional to how much it hurts so when we're talking about how to survive a 5-mile fall with no parachute what are you thinking just somehow you don't want that to be an instantaneous end how can you lengthen out the time well this actually happened a dude fell from 2,000 feet his parachute failed this is him right here his name is Paul Lewis this is in 2009 he landed on the roof his parachute failed he landed on the roof of an airplane hangar and was one of those metal really flexi roofs and he ran in and in just the right spot and the time was long enough for the deceleration that he didn't even break any bones he he did say after that he wasn't gonna go skydiving again which I really can't blame him and then specifically for our answer there was actually a guy who fell from five miles and this is the clip right here five miles up he's got no parachute check out what and the crowd on the ground looking up they have a visual on him right now he's in [Applause] and he's kicking and moving from here and look perfect you just so he used the net but you really could have you could have used anything right you could have used a platform with rockets you could add rockets on his back you know that's where people do use packing peanuts anything to just extend the time for him to land he chose to use in that so if you want to know how to survive with no parachute just figure out some way to extend the time maybe take a big big big bucket of packing peanuts okay so I'm gonna leave you with the final thought alright this is it and it's to stay curious before I get into this final thought though you can come back to me Alex we're gonna try this one more time I've been informed for my massive quarantine level crew here of three of us that we may be in good shape again so we're just go try it if it doesn't work just know that I still love you but if it does then it'll be heroic okay here we go alright so let's just see what happens all right don't be mad at me if this doesn't work this is live this is what you get is what you pay for here we go three I'm waiting for the camera guy over here okay here we go ready Josh good okay three two oh I glasses with safety first okay three two one there you go boom what a way to end science class and for the record duct tape killed Ken this looking great is is kill fell down a little in the back but other than that yeah we're in good shape dr. croquette that was a PC my part is totally racing oh yeah my final thought is to stay curious okay we will have science class here but every day can be a science class for you all right the key to that is observation if you're observing the world around you and just makes you thinking about things and wondering and asking questions you have Google you can answer these questions I love to think of things to talk with with my friends who loved and talked about these types of things as well just random questions so if you don't have someone to find your tribe isn't online find people who like to talk about this stuff especially science stuff I just want to give you an example of this I've got driving in the car I have my laptop down here because I knew a good glass on it we can go to the laptop screen Alex so driving in the car I here are a couple questions you know I was just thinking what's an example what I mean by stay curious let me just give you some questions that I've thought of in the scenario of being in my car all right what why do these rail why do you signs like this have these holes at the bottom you ever thought about that have you ever even seen that right so step one of the scientific method is observing why is that they have to do with crashes I'm not going to tell you the answer these I want you to wonder yourself why do some of these trucks have these little doors on the back what's the purpose of those cute little doors I'll give you a clue that tends to be refrigerated trucks what's the purpose of these things have you ever even noticed them before they're actually pretty common they go around the nuts what might those before again this is sort of a safety thing that makes visually useful safety check how do people how do they know and people when cars are at lice someone told me once they have scales and that never made sense to me I don't think scales there's a different way maybe you've seen these cuts in the concrete have to do with induction and wires of current magnetic fields how are things reflective a normal sign is on the left but just with your headlights these signs becomes so they almost like shine back at you completely passive passes with a retroreflection so all of these things are like Google Bowl hopefully some of these get your heart pump and you're like yeah these are good questions what's the purpose of these things this actually has a lot to do with our class today right here okay clue is that they're filled a lot of times with water or sand so I'm gonna leave you guys with that I will say for me per like even with my wife she's an English major so we make a great combo and you know a lot of times I'll be like have you ever wondered why she's like oh boy here we go again right so when we spend like a certain amount of time talking about nerdy stuff we got to talk about like feelings and stuff to keep it balanced conservation of conversation that's one of Newton's fourth principle I think but yeah or sometimes we'll just be like hugging or whatever we'll be like talking and they'll be like a lull in the conversation she'd be like are you thinking about like your next video and you know sometimes I'm guilty like I give these things in my head and I'm stoked about them and I think about them and it's just like a great rewarding way to with live life where you're curious about the natural world around you and you try and find the answers so even though we won't have science class here you have science class in your heart forever more and hopefully what we've done here has helped instill that passion within you so be good prioritize your physical and your mental health and I'll see you guys around on the Internet and as always thanks for watching [Music]

Channel: Mark Rober

Views: 4,381,022

Rating: 4.8720336 out of 5

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Id: 3yjcqsNNa24

Length: 33min 42sec (2022 seconds)

Published: Wed May 06 2020