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Old 08-11-2016, 10:16 AM
Leo Bloom Leo Bloom is offline
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Gymnastics on the Moon

Olympics prompted. Gymnastics on the Moon would be awesome, and all sorts of new maneuvers, eg "the 1/2 Bloom," which is too difficult too describe here. But to begin, my original thought/query. There are any number of maneuvers--I don't know the real word--often named after their creator, which are analyzed as, eg ["two flips with planked body"] followed by ["two spins around body axis"], etc. I'm using brackets because the technical description is very precise and I don't know the words anyway.

Basic physics question: can you extrapolate using elementary dynamics how a maneuver on Earth would play out in a different gravity, all other things being equal?

I.e., would a "triple Bloom" on earth be a "36-Bloom" on the moon?


ETA: Mods, if you can, leave this in this GQ forum. It should be the physics and physiology of a hypothetical, not a Fantasy Sport.

Last edited by Leo Bloom; 08-11-2016 at 10:19 AM.
  #2  
Old 08-11-2016, 10:30 AM
TriPolar TriPolar is offline
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Sticking the landing will be a lot easier on the legs.
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Old 08-11-2016, 10:55 AM
markn+ markn+ is offline
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Less stressful on the legs perhaps, but harder to achieve. You'd tend to bounce more, I'd think.

--Mark
  #4  
Old 08-11-2016, 01:13 PM
Marvin the Martian Marvin the Martian is offline
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Quote:
Originally Posted by TriPolar View Post
Sticking the landing will be a lot easier on the legs.
If you apply the same upward force when you jump as you would on Earth, you will still need to apply the same amount of force to stop your body when you land. You'll just jump higher.
  #5  
Old 08-11-2016, 10:54 AM
watchwolf49 watchwolf49 is online now
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I've fallen and can't get back up ... YouTube video of astronaut on Moon.
  #6  
Old 08-11-2016, 11:19 AM
muttrox muttrox is offline
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All else being equal, I believe gravity is roughly 1/6 - the same muscle power gets you proportionally more height and time in the air to do stuff.
  #7  
Old 08-11-2016, 01:17 PM
muttrox muttrox is offline
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But impact may be spread over more time. Your muscles have more time to absorb the equivalent change in force. Er... actually I think the work is equal, so you need to apply less force over more time. If I remember my physics correctly.
  #8  
Old 08-11-2016, 01:20 PM
scr4 scr4 is offline
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Originally Posted by muttrox View Post
But impact may be spread over more time. Your muscles have more time to absorb the equivalent change in force.
No, if you take off with the same amount of force, then you leave the ground at the same speed, regardless of gravity. It's just a function of force and mass. Gravity only affects how quickly you decelerate after leaving the ground, which affects how high you get, and how soon you come back down. When you do come down, you hit the ground at the same speed.

Last edited by scr4; 08-11-2016 at 01:20 PM.
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Old 08-11-2016, 02:03 PM
TriPolar TriPolar is offline
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Originally Posted by scr4 View Post
No, if you take off with the same amount of force, then you leave the ground at the same speed, regardless of gravity. It's just a function of force and mass. Gravity only affects how quickly you decelerate after leaving the ground, which affects how high you get, and how soon you come back down. When you do come down, you hit the ground at the same speed.
Yes, but isn't there less impact on the legs? That's what I was talking about, fewer injuries.
  #10  
Old 08-11-2016, 03:36 PM
scr4 scr4 is offline
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Originally Posted by TriPolar View Post
Yes, but isn't there less impact on the legs? That's what I was talking about, fewer injuries.
If you jump up from the floor with the same amount of effort, then you come back down just as fast on the Moon as on the Earth. So the stress on your legs from landing should be the same.

Or to put it another way - on the Moon, you can jump 6 times higher, so you're falling from a height 6 times higher.

Last edited by scr4; 08-11-2016 at 03:40 PM.
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Old 08-11-2016, 03:45 PM
TriPolar TriPolar is offline
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Originally Posted by scr4 View Post
If you jump up from the floor with the same amount of effort, then you come back down just as fast on the Moon as on the Earth. So the stress on your legs from landing should be the same.

Or to put it another way - on the Moon, you can jump 6 times higher, so you're falling from a height 6 times higher.
Ok, but you don't have to jump as high to start with on the moon. On earth it's hard to stick a landing for the minimal moves. On the moon you can do much more without coming down so hard. So yeah, if you take advantage of maximum height for the most complex moves then I guess you'll hit just as hard.
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Old 08-11-2016, 01:29 PM
Bryan Ekers Bryan Ekers is offline
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Well, if you jump like a figure skater with your arms and legs held far out and then pull your limbs in quickly to convert angular momentum to rotational, I guess the extra "hang time" might allow for a septuple+ axel.

Probably the bigger problem is how to maintain athletic conditioning in a low-gee environment. Even if you start out as an Olympian, the longer you stay on the moon, the "softer" you'll get. Would it be possible to stay in Olympic shape even with extended hours of daily resistance training? The cooler impossible-on-Earth gymnastic moves might only be doable for a few months.
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Old 08-11-2016, 01:40 PM
muttrox muttrox is offline
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Thanks scr4. Wasn't thinking right.
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Old 08-11-2016, 01:49 PM
Bryan Ekers Bryan Ekers is offline
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Thanks scr4. Wasn't thinking right.
Well, there's the minor wrinkle of terminal velocity. As pointed out in this long-ago thread, the moon doesn't have terminal velocity as such since it has no atmosphere, but if we're staging a Moonlympics in a stadium-sized dome with Earth-level air pressure so the athletes won't have to wear bulky spacesuits...

Well, probably there's no appreciable effect anyway. I just picture a pole-vaulter able to land without a mat by flapping his arms after he clears the bar.
  #15  
Old 08-11-2016, 06:46 PM
Chronos Chronos is offline
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Picture an athlete six times stronger than a normal human. Train them in gymnastics, and have them do their best in an Earthly gymnasium. Then slow down the film by a factor of sqrt(6). That's exactly what a normal gymnast would look like on the Moon.

EDIT: Whoa, the two space stations are that close in volume? I'd have expected that the ISS would be several times larger than Skylab, not just a hair more.

Last edited by Chronos; 08-11-2016 at 06:47 PM.
  #16  
Old 08-11-2016, 07:07 PM
engineer_comp_geek engineer_comp_geek is offline
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One thing the astronauts discovered on the moon was that while things like jumping up were pretty straightforward (you just end up jumping about 6 times as high, as was already mentioned), other things weren't so straightforward. Walking, running, and other motions rely on a certain amount of friction between you and the surface you are on, and the moon's reduced gravity reduces the friction as well. So if you try to run, all you end up doing is slipping your feet. As a result, the astronauts found that the easiest way to move across the lunar surface was to bunny hop.

If they tried to do a normal 100 yard dash on the moon, it would end up as a rather comical event of athletes cartoonishly running with their feet slipping on the surface while barely moving forward. A lot of other typical earth-based sports would be similarly affected.
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Old 08-11-2016, 07:58 PM
Hail Ants Hail Ants is offline
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Quote:
Originally Posted by engineer_comp_geek View Post
One thing the astronauts discovered on the moon was that while things like jumping up were pretty straightforward (you just end up jumping about 6 times as high, as was already mentioned), other things weren't so straightforward. Walking, running, and other motions rely on a certain amount of friction between you and the surface you are on, and the moon's reduced gravity reduces the friction as well. So if you try to run, all you end up doing is slipping your feet. As a result, the astronauts found that the easiest way to move across the lunar surface was to bunny hop.
Along with allowing zero-G simulation the 'vomit comet' could alter its parabolic course and instead simulate the 1/6 gravity of the Moon as well. I can't find the footage of it but I've seen film of the Apollo astronauts wearing their lunar surface suits and practicing walking and moving around inside the plane (on a simulated lunar surface) in just this manner.
  #18  
Old 08-11-2016, 08:47 PM
Blue Blistering Barnacle Blue Blistering Barnacle is online now
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Quote:
Originally Posted by Hail Ants View Post
Along with allowing zero-G simulation the 'vomit comet' could alter its parabolic course and instead simulate the 1/6 gravity of the Moon as well. I can't find the footage of it but I've seen film of the Apollo astronauts wearing their lunar surface suits and practicing walking and moving around inside the plane (on a simulated lunar surface) in just this manner.
They did that on MythBusters, too.
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Old 08-16-2016, 06:52 PM
markn+ markn+ is offline
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Randall Munroe did an article on lunar swimming, in which he concludes, among other awesome results, that Michael Phelps could probably jump out of a pool on the Moon 2 to 3 meters into the air, and a champion finswimmer could reach 4 to 5 meters.

--Mark
  #20  
Old 08-17-2016, 07:20 AM
Melbourne Melbourne is offline
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Quote:
Originally Posted by engineer_comp_geek View Post
If they tried to do a normal 100 yard dash on the moon, it would end up as a rather comical event of athletes cartoonishly running with their feet slipping on the surface while barely moving forward. A lot of other typical earth-based sports would be similarly affected.
Boxing. Either they'd adjust to the lack of friction by letting their feet slide, or they'd change their action to get an equal-and-oposite effect (backwards kick? Running roundhouse?). Also, they could lean in and out a lot farther! It would be a whole new discipline.

(Ok, actually they'd probably just put on sticky shoes or roughen the ring floor)
  #21  
Old 08-11-2016, 07:10 PM
Dr. Strangelove Dr. Strangelove is offline
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The outer diameter of SkyLab was 6.6 m, as compared to ~4.5 m for most ISS modules, but it's pretty clear that a huge fraction of the ISS volume is taken by non-habitable space, whereas much of SkyLab (in particular, the ring shown above) gets almost the full diameter. Wouldn't surprise me if the effective diameters were something like 2 m vs. 6 m. That factor of 9 makes up for a lot of missing length.
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