10 ms·
How far can you jump from a swing?
- amelius 3y agoArbitrarily far if you jump if the swing is furthest back.
- amluto 3y agoThat’s a good point. I assume the author meant jumping by ejecting oneself with no momentum transfer. But winning a competition by following the unstated rules isn’t always the right choice :) You can also jump arbitrarily far by jumping off the swing at its lowest point.
- checkyoursudo 3y agoAlternatively, infinitely far (into stable orbit) if the swing is tall enough and you have enough momentum.
- brianpan 3y agoNot yet! https://www.youtube.com/watch?v=M_50TM3OeEw https://www.youtube.com/watch?v=M_50TM3OeEw
- _fs 3y ago[flagged]
- bhaney 3y ago> 32.63 million meters [...] is more than five times longer than the diameter of the Earth (12.74 million meters) These walls of generated bullshit should just be considered spam at this point.
- amluto 3y agoEven ignoring the egregiously nonsensical numbers: > The reason is that the gravitational force of the Earth decreases with distance, so as you go higher, the force pulling you back becomes weaker. This means that your potential energy increases as you go higher. Saying “this means that” does not make it in any respect correct.
- iso1631 3y agoYou wouldn't be able to get into orbit with a single launch. You could reach escape velocity (assuming you didn't burn up leaving the atmosphere), or a balistic trajectory. In theory on a perfectly uniform sphere in a vacuum if you stood on a ladder, launched parallel to the ground, and knocked the ladder over on launch, you'd be in a pretty stable orbit with a periapsis of the height of the ladder. If you didn't knock the ladder, even with a rotating sphere, eventually your orbit would coincide with the ladder again. (I'm not sure how much frame dragging would cause your orbit to decay and there may be some other issues, like solar pressure) To get into "stable" orbit (what does stable mean) in the real world you'd need to change your direction once you reached a certain height (typically above the majority of air). A single launch would form an orbit which intersect with your starting point (which even if you started on top of Chimborazo would still have plenty of air resistance)
- checkyoursudo 3y agoI think we are just making some different assumptions. TFA also made a whole bunch of unreasonable assumptions, such as maximum time allowed on the swing, a certain height for the beam, no mention of rocket-assist at all... When you were a kid, did you ever make the swing complete a full revolution? Not while you were sitting on it, pumping it yourself of course. But the headline and proposed question of TFA was simply "How far can you jump from a swing?" So I just made some different assumptions. Build a swing such that the beam is about 75km off the ground or maybe just a bit more to be safe, with about 75km long suspension tethers for the seat to hang on. Get your rocket-boosted seat going at whatever velocity you need to make a full revolution plus inserting yourself into orbit at around 150km. Once your seat reaches right about the zenith of the swing's circular path, along the line running from you through the beam perpendicular to the tangent of the earth's surface below, you jump. Or "jump", since you'll mostly be upside down and puking into your fantasy tech space suit or whatever you need to get this done. Since the seat, no longer rocket boosted, will experience a nice amount of drag once it re-enters the atmosphere, you don't even have to worry about colliding with it anymore either. I don't see what the problem is. By stable orbit I just mean one that does not suffer atmospheric drag, since you won't have any extra propulsion once you jump. Probably. Who knows. Do whatever you want. Reckoning with other possible sources of orbital decay is too far outside of this nonsense to bother with. :)
- dang 3y agoRecent and related: How far can you jump from a swing? - https://news.ycombinator.com/item?id=37255330 https://news.ycombinator.com/item?id=37255330 - Aug 2023 (28 comments) (I invited the author to repost it because while that thread got some comments, it never made the front page, and it seemed like a good candidate for the SCP (https://news.ycombinator.com/item?id=26998308 https://news.ycombinator.com/item?id=26998308).)
- amluto 3y ago> The paper proceeds by assuming the swinger pumps the swing by forcing [sinusoidal pumping]. I doubt that’s particularly close to optimal. I’ve generally assumed, without proof, that the optimal pumping strategy is to change one’s position abruptly at the highest point. The intuition is that this delivers all of the fixed amount of available angular displacement at the position in which it adds the most energy to the system.
- version_five 3y agoThere could be some dynamics I'm overlooking that make your theory work. Normally with a resonant system, energy essentially gets added near the resonant frequency and it acts as a bandpass filter for everything else, so my guess is it's only the first harmonic of whatever jerking motion you try that's actually contributing energy. As I say, that's really for a simple oscillator, there may be something about the swing system that gives it an impulse response that matches what you are describing. Edit: I wonder if the abrupt change is better simply because it lets a person maximize the amplitude of the push they give, so more energy goes in at the first harmonic anyway. That's probably the explanation.
- amluto 3y agoBut the process isn’t energy-limited — it’s displacement limited. Your arms have a certain length, your body has a certain mass distribution, and you can force the angle by a certain amount. So, if you want a heuristic, integrate pumping displacement times swing position, where the pumping displacement has a fixed maximum. The result is maximized by a square wave.
- avar 3y agoIsn't the flaw that the posted model assumes that you're essentially bolted to the swing by your ass, and only able to move your legs and upper body, excluding the arms? Whereas an actual person on a swing has two points of contact along the pendulum: where they sit, but also the point at where their arms are grabbing the rope (or "rod", in this model). I think what the GP is talking about is a technique where you essentially perform a partial pull-up near the top of the arch.
- thedanbob 3y agoAs an avid swing jumper in my youth I can say with some certainty that 3m is closer to the mark than 2. Also, my brother and I devised a variant that would work for the winter Olympics: jump at the lowest point of the swing for maximum velocity and slide over the snow.
- estebarb 3y agoI came to say too that 3m is more realistic, from what I did in school. Also, around 1-2m is possible if you jump backwards, but you may end up visiting the hospital as well. At my school the swing was near a clift, so sometimes you were able to combine swing jump, ski jump and hospital visit with a single jump. Good times XD
- ShadowBanThis01 3y agoClift?
- hardlianotion 3y agocliff?
- estebarb 3y agoLOL, by bad, I wanted to say hill instead. For reference, here is a recent photo: https://mcs.ed.cr/wp-content/uploads/2023/03/WhatsApp-Image-2023-03-23-at-14.40.55.jpeg https://mcs.ed.cr/wp-content/uploads/2023/03/WhatsApp-Image-... . They had the swing in the hill (yes, now I know the difference) where now there is the second floor of the 3 stories building in the center. So if we jumped too far we end up more or less near the small yellow roofs that I think are a playground. So no, it was a hill, not a cliff. Not being a native English speaker bites me again XD
- dgfitz 3y agoI agree, and in my experience the taller the swing in terms of rope/chain length, the further I could jump.
- micw 3y agoEmpirical determined short answer: way too far. I tried this years ago when I was with my kids on a playground and broke me a toe that way.
- crocal 3y agoI concur. I broke my wrist.
- vvpan 3y ago[flagged]
- kirse 3y agoI had a friend in 2nd or 3rd grade who would stand on the swing seat to use his legs to assist with gaining height and then eventually do a backflip with the chains near parallel. Of course we always begged him to show off this trick every recess. Looking back now I have no idea where he got the idea or how he practiced his way into it, but he was always a playground daredevil who routinely made teachers come sprinting over the tarmac. I will say you knew you jumped far when that playground mulch embedded itself in your hands and knees.
- pak9rabid 3y agoHeh, I remember a group of us doing that as well. Also "penny drops" off the monkey bars, where you'd hang upside-down with your legs, swing back and forth, release and essentially do a flip and land on your feet. God we were fearless back in the day.
- Fricken 3y agoWe called those "baby drops", and flipping back off the swing seat as it comes forward we called "cherry pickers". I'm 46 now, I can still do both. Once you've learned them, they're easy.
- dylan604 3y agocan and do are two different things. things heal a lot faster when the landings are wrong in playground days than they do at 46. i have personal experience with the healing slower bit if not from a cherry picker move.
- helf 3y ago[dead]
- lampshades 3y ago[dead]
- avar 3y agoThe proposed Olympic sport seems like an elaborate reinvention of the standing long jump [1], just executed at an angle, and standing on a moving, unstable and elevated platform. Clearly the author expects (and the interesting mathematical problem is) that the athletes would restrict themselves to the swing itself to gain momentum. But nothing about the proposed rules prevents one from standing on the swing, and jumping forward at an angle on the backwards swing. 1. https://en.wikipedia.org/wiki/Standing_long_jump https://en.wikipedia.org/wiki/Standing_long_jump
- deleted 3y ago[deleted]
- amluto 3y ago> But nothing about the proposed rules prevents one from standing on the swing, and jumping forward at an angle on the backwards swing. That doesn’t sound like a very good strategy. The athlete is likely much heavier than the swing, and applying a backwards force to the swing will mostly just push the swing back. As mentioned elsewhere in the comments, one strategy is to jump off the swing at the farthest back point (so the jumping force is mostly balanced by the chain). Another is to jump up while the swing is moving forward. Some combination should work too.
- avar 3y agoIf you think you can jump up, then you can also jump forward by jumping "up". it's just a matter of what angle the swing is at when you execute the jump. It's clearly trickier than a standing long jump, but mostly the same. One way to think about it is that it's similar to jumping from a stationary platform situated on the ground that's continually tilting between 45° backwards and forwards. The major difference is that even if the stationary platform is at 0° you can still get traction, but a swing will just be pushed back unless you're at the optimal angle, as you correctly point out. But if you time that jump exactly right the swing will behave like a rigid platform tilted 45° forward. At which point the proposed Olympic sport is just a standing long jump on a 45° elevated platform, with the added requirement of exquisite timing.
- 3y ago
- lvl102 3y agoGrew up with swings in a sandpit. Some of my best memories jumping from a swing. I’d never let my kids do that though.
- whats_a_quasar 3y agoWhy not? If you look back, are you glad that your parents let you jump far from swings?
- donutz 3y agoWho said the parents did any letting, or even knew you were jumping from a swing back in those days?
- lvl102 3y agoI did a lot of stupid things as a child. 80s were definitely different times. Sometimes, I think I am lucky to be alive. Life is about knowing when and how to take risks. I took unnecessary risks as a child. Plus even if I let my kids go free, I know there will be eager parents willing to call the CPS for the slightest oversight. For better or worse, we live in a very different world.
- 1letterunixname 3y agoThere was a park near my aunt that had a decommissioned delta wing Korean War jet in the sand pit and a caged steel sculpture that doubled as a maze for kids. Nothing of the sort can be found today because of the cultural shift to helicopter parenting and placing zero risk above all else. I'm wondering if kids today grow up without as much of an understanding of their physical boundaries as a result.
- famahar 3y agoI have fond memories of having swing jumping competitions as a kid. No major injuries. My parents definitely wouldn't approve, but they also would never know. Your kids will probably still do it given the chance. It's too much fun. From what I remember reading, playgrounds are kind of engineered in a way for encourage kids to take potentially painful risks without severely injuring themselves.
- badcarbine 3y agoFar enough to break bones
- ShadowBanThis01 3y agoImportant point I discovered when doing this for years growing up: You need swings with wooden seats. Jumping out of swings with the rubber-sling seats SUCKS. I stopped bothering.
- famahar 3y agoA lot of parks in the city I grew up in replaced wooden structures in parks with steel and rubber. I think the rationale was that wood was hard to maintain and also super dangerous when it turned into a splinter. We're too squishy for wood.
- ShadowBanThis01 3y agoOh yeah, I never questioned why the swings were rubber. They just don't work for jumping!
- JKCalhoun 3y agoIllustration is based on a Maxfield Parrish painting: https://www.paintingstar.com/static/gallery/2008/01/10/52d2428742fe8.jpg?Swing+Artwork+by+Maxfield+Parrish https://www.paintingstar.com/static/gallery/2008/01/10/52d24...
- ggm 3y agoFragonard is knocking on the door (It's in the Wallace Collection in London. Colloquially me and my friends call it "the up-skirter of the 18th century") https://www.wallacecollection.org/explore/collection/search-the-collection/les-hazards-heureux-de-lescarpolette-swing/ https://www.wallacecollection.org/explore/collection/search-...
- optimalsolver 3y agoDid everyone else have an immediate childhood flashback after reading that title?
- cwoolfe 3y agoHaving skimmed the paper...Can you all help me interpret the findings? It appears that the longer you ride the swing, the farther you can jump tending toward infinity? I was looking for some kind of min/max for optimization. What am I missing?
- chrischen 3y agoSame. What is the actual angle that one should jump at to maximize distance?
- SamBam 3y agoI think that the author felt that question had already been answered sufficiently by other papers -- his citations 1 and 2. The author was interested in adding pumping to the model, but as far as I can understand the pumping equations only work for low angles, so he restricted his work to those low angles. Within that range, the distance only increases as the angle increases. Someone can correct me if I've misunderstood.
- firesteelrain 3y agoI swear my little kid self swung further than 2m
- dcanelhas 3y agoA swing with rigid rods (as opposed to ropes or chains) can potentially spin all the way around its hinges. If you ignore friction and keep adding energy at the right frequency (once it becomes a rotary system instead of a pendulum, it will increase as speed picks up) and jump off at a good ballistic angle, is there really any reason why you can't reach the cold dark voids of outer space?
- ljlolel 3y agohttps://www.spinlaunch.com/ https://www.spinlaunch.com/
- ChatGTP 3y agoThe maintenance on that thing must be wild?
- hnben 3y agohttps://www.youtube.com/watch?v=yrc632oilWo https://www.youtube.com/watch?v=yrc632oilWo tldw: it is.
- wraptile 3y agoThat has the be the most disappointing rocket launch video ever. Could they really not put a camera on it or show the launch itself for longer than 1.5 seconds? It almost feels like they're hiding something.
- hk__2 3y agoMeta: > There are several papers about the pumping of a swing ³, ⁴, and ⁵ and much more. In this section, I’ll focus in particular on ⁴. Either those little numbers are references to footnotes, and so are outside of the text flow, either they are part of it. Here the text explicitely use them ("I’ll focus in particular on ⁴") but still put them in superscript with role=doc-noteref, meaning screen readers will skip them. (I simulated <sup> with unicode chars because HN doesn’t support HTML)
- nwatson 3y agoMy daughter (nine years old at the time) was wearing shorts and went to jump from our backyard swing. She let go of the chain at a good time, but her slightly sweating leg skin stuck to the flexible plastic/rubber swing. She ended up swinging back and fell forward on the backward upswing and would have landed straight on her head ... but she broke her fall with her right arm. She broke both bones in her forearm and had some metal support rods in them for six months while they healed. My wife and I were sitting right by the swing when it happened and could do nothing about it. My daughter quite possibly saved herself from a broken neck.
- __MatrixMan__ 3y agoMy elementary school responded to the swing jumping threat by putting a fence in the way. But they put it just close enough that you could jump over it if you were really ambitious and get hurt pretty bad if you hesitated. I still wonder if the move was 100% oversight or if somebody on staff recognized the lesson in it: be good or be good at it.
- Amorymeltzer 3y agoI was recently on a good empty playground with my kids, and the major factors limiting my swing jump distance were the width of my shoulders and hips! They limit your ability to slip out, especially your shoulders, which you want behind the chains to pump but in front to jump. It's a youngster's game!