JSC (AV) - Skylab 4 - Scientific Demonstration - TV 107 - Earth Surface Features - TV 78-9 Part 4

Description

TH78 FR A238 SKYLAB 4 KINESCOPE TAPE 14, PART 3 of 3 The simplest shape that a fluid body can take in the absence of any forces external to its own is a sphere, beautiful in its own way. We're lookng at a sphere of water which is held together by its own surface tension. We're able to do this up here without the sphere falling to the floor or flattening out on the plate as it would down there because there is no gravity up here, only force acting on the water is the tension on the outside which holds it all together. This gives a unique opportunity to study some of the fundamental problems of fluid mechanics which has a fair amount of application in other fields. First we're gonna' look at the sphere and we're gonna' cause it to oscillate to see what the modes of oscillation are, that is, what shape it takes, what changes the shape takes, moves around, and then how fast it decays, or damps out. That particular study - there are some particular applications in the field of nuclear physics, understanding one particular model of a nucleus, and also in astrophysics, although there, the force that holds the fluid together is gravity, self-gravity, like a star, as opposed to surface tension, the sphere here being quite a bit smaller than what's required to have in the internal gravity of its own. So we'll start out here with a 50cc sphere of water, slightly colored, and we'll try to induce in it a symmetric oscillation, lightly contacted on either side, and by pulling away rapidly, we hope for a symmetric oscillation. Okay, we did have a symmetric oscillation for a little while, but then the asymmetry that were induced caught up with us eventually. We'll let this damp out and then we'll try it again. Okay there's a good one we'll try that just once more - and then we'll try it in the opposite direction. Okay, let's try it again - let me move our line of sight down so we get a good background again. This time we'll try to get the oscillation so that the long direction is toward you in your line of Sight. Better warn you, occasionally we have a slight slipup, so I hope y'all (garble) okay. Here we go. Rather than watch that one, let's try that one again. That particular start was not too good. All right, now we'll induce an asymmetrical oscillation. By that, we mean we won't have both sides trying to do the same thing at the same time, but rather just the opposite, try to bring it down here into your line of sight. Hold still there okay. I think thatillustrated it pretty good I personally find the modes of oscillation here rather interesting, and I Took forward to getting back and trying to figure out just how you would calculate these. I think we're Page 2 Ragex seeing just the fundamental modes of oscillation. May be able to see (garble) some of the harmonics or second and third modes we'll try the asymmetrical once again. Okay, there goes our friend, drifting off. Let me bring him back here and we'll try that one again. Come on home okay, I got the oscillation or the line of sight now in the center let me get that fixed and we'll have another go one more asymmetrical now that was also irregular - that was not very satisfying from the camera angle standpoint. Let me see if I can't get you a good one. Okay, we are going before we pass on, let's take our friend here and make a place his size and see how he behaves. We're looking here at big brother - this fellow is 100 cc's of fluid, water, colored slightly. And we're going to try to induce in it the same oscillations which we've seen before. What we expect is the shape or the modes of oscillation will remain the same, but the frequency could be a little bit lower, could take longer to go through the same changes in shape, just because it's more massive compared to the surface which is what really brings it back in, that is the tension on the surface, and the restoring force, the mass is proportional to the volume that we have, so the larger we make it, the longer the time should be for the oscillations. And the damping, I will not make a guess on right now. It usually ends up in this type of oscillation, but unfor- tunately, for you viewing it, we cannot always see it very clearly. Especially it goes to elliptical shape in one direction, and then moves into elliptical shape 90 degrees from that. I'd like to start the oscillation along an axis which is exactly perpendicular to your line of sight, and then you'll be able to follow that, but as you can see, this is a slick little customer, and he likes to juggle around once you give him the slightest little motion. Come on, old friend, steady big fellow okay now, there's what I would call a square oscillation which we've seenbefore. It tends to oscillate so that extreme oscillation it looks like a square with rounded corners like that. That's damped out pretty well. I'll slide one along your line of sight, and if this fellow lets go, you're really gonna' get wet. Okay, from my point of view, it looks exactly as we've had before, so you're seeing the edge-on view now. Let's try an asymmetrical one let the fellow damp down a little here okay, we got a regular one by that, I mean it's just almost nearly random the problem with starting this of course is that you've got to guess the frequency before you start, SO that one hand moves away exactly toward

Collection

Records of the National Aeronautics and Space Administration

Series

Moving Images Relating to Documentary Stock Footage