Thank you. How would you cut the bottoms if they were one piece? I suppose it's possible they used an EDM wire to drill the pass-through, but that could easily have been done with a regular drill and a plug.
@Tb0n3 there has to be a hole to feed the cutting wite through - and of course the wire itself makes a gap. Once the pieces are assembled the sides are milled - so the joins become impossible to spot.
Just to be clear... The "slugs" in that block were NOT cut from "that" block. They were cut from a second block and fitted to the cavities of the first. The kerf (waste) of the wire EDM process is ~0.013" (0.33mm) per side. A tool maker might say, that's like throwing a hotdog down a hallway.
0.013"? If that was typical these days for wire EDM, it would be worthless for the cost. I get your point, but the inserts are way tighter tolerance than 0.013" on the perimeter.
I just did the math. The absolute pressure is about 5000Pa in the chamber. This means if the absolute pressure created inside the block is approximately 0, the maximum force based on a 1"x0.5" plunger is about 0.34 pounds, which is most definitely more than the weight of one of those blocks. Very cool!
@@It-b-Blair I'm pretty sure this was a problem in space with some equipment, so it can happen to other materials but it needs to be a clean surface. Probably this cube has a coating that prevents cold welding, such as stainless steel or aluminium gets naturally to prevent corosion.
@@tortex1 no need for a coating. all metal exposed to the earths atmosphere will quickly develop a thin layer of oxide that prevents cold welding. If you scratch off this oxide layer in space, the lack of atmosphere prevents the oxide layer from reforming, and cold welding at that spot is possible
This is a very interesting video. I was surprised to see that the metal parts only fell out a little faster under vacuum. However, I was thinking a "full" vacuum, and now I realize that the vacuum wasn't very strong. I would really like to see the experiment with even stronger levels of vacuum! However, I think you might have missed that the reason the plunger of the syringe falls faster in the beginning is that there is less pressure inside of the syringe, however as the plunger falls, the relative pressure between the syringe and the pressure inside of the needle itself begins to even out, so in fact, there is more pressure inside of the syringe as it gets closer to the needle.
@@rhettbaldwin8320is there any particular reason you say that? Because with my limited knowledge on vacuums and materials it seems just as likely that they slide apart as fast as possible when accounting for friction. So I’m curious if you have anything academic to teach me what happens
Depends on how long you keep them in the vacuum. Right away they probably move fast since air pressure stops being a factor. But over time - not sure how long - the oxidation layer will wear off and they will contact weld to one another and seize up. This is a problem spacecraft run into, and they require special lubricants to solve it.
i thought the same but he doesn't get enough vacuum and his surfaces are not smooth enough possibly. i suggest gage blocks stuck together as they stick to each other because they are so smooth.
His vacuum is several orders of magnitude off from achieving cold welding, or stripping metal oxide layers. I had the same thought before the video started though.
That sounds like a neat experiment. Would adding "something" (a low viscosity gas) actually decrease the viscosity of "nothing" (a partial vacuum)? It would seem counterintuitive for that to happen, but given that 0.05 atm is far from "nothing", seeing how different gases interact with one another with respect to viscosity would be interesting.
He atoms. H molecules. H would be similar to air since its around the same size molecule as airs components. Any Noble gas would be way smaller than H. Good idea, tho.
One other thing to consider is the dynamics of flow through a pipe. Flow rate is determined by delta pressure (and viscosity which, as noted, is usually constant). Since this pipe is so tiny, it has a very small maximum flow rate, and therefore a very small delta pressure. Since delta pressure doesn't care about ambient pressure, the flow rate through the pipe is the same, whether or not ambient pressure is super low or super high. If there are enough molecules to generate a delta P, the syringe will always fall at the same rate.
Counterintuitively, many properties of ideal gases depend only on temperature and are independent of pressure: enthalpy, viscosity, speed of sound to name a few. Interestingly, both viscosity and speed of sound are both proportional to the square root of the absolute temperature. Yes, viscosity of gases INCREASES with temperature as the mechanism of viscosity is totally different than in liquids (momentum transfer between layers which occurs faster the faster the particles of the gas move)
I think the effect we see here is also related to soda outgassing. It doesn't matter how much air you pump into an open soda bottle, it will still go flat at almost the same rate as if it were at outside pressure. The only solution is to pump in the same gas, carbon dioxide, into the bottle.
Absolutely love your videos! I've seen these perfectly machined steel things before, but it's really cool what you tested with the vacuum for it! Love your fresh experiments!
Your videos never cease to amaze me! That's not what I expected and I have to say, is still counterintuitive to me! Your explanation of the gas molecules slipping past one another kinda makes sense though.
1:12 I really appreciate seeing someone finally handle these like a normal person. With all of the jitter and imperfect human movement that videos of these machined parts usually refuse to show, since all of them want to be "satisfying". This really helped me understand this a bit better and in turn was MORE satisfying
I worked on a laser tube cutter years ago, that used finely ground parallel metal surfaces in a vacuum to generate the beam. I was told that those surfaces were ground so flat that if they ever came together you would never get them apart.
@5:55 The cube is moving down in the same way on both sides, so the net force on the cube should be the same. Yet the reported pressure difference between the inside and outside of the syringe is different--it's a higher delta in the vacuum by a significant fraction. The only other factor I can think of is the buoyant force of air on the cube, is that enough to explain the increased "weight" of the cube on the right? And given this increase in deltaP, is it really fair to call the viscosity equal between the two scenarios?
Wow, James I love how you figure out the tricks you need to use to manipulate things when you have to interact through a wall, such as part of the vacuum chamber!
Cool!! I was hoping for some space cold welding… Could you try clamping two close fitting metal surfaces together in a vacuum and running a test of DC voltages through them to see what happens?
@@nagjrcjasonbower Cold welding required a vacuum several orders of magnitude more empty than what he's using here. It also requires materials that are very clean, including of oxide layers. Gold is easy to cold weld, stainless steel is pretty difficult and usually requires some mechanical abrasion while in the vacuum to expose the bare metal.
I definitely wasn't expecting the viscosity to plateau like that. I wonder if there's a macroscopic scale demonstration that could show why that plateauing happens?
The reason this happens is because of pressure differential. Eventually, the small gap allows the inside and outside pressures to equalize and the assembly behaves the same as at room atmospheric pressure. An absolute vacuum, like absolute zero temperature. is impossible to achieve.
@@peteroleary9447it's like amount of particles per volume you can get it extremely low though. If it's 1 particle per m³ it's not too bad. 1 part per nm³ and it's a much less useful vacuum. Temperature is similar, you try to stop all the atoms but outside stuff tries to bump into it and everything tends to jiggle, and there's radiation that makes things jiggle. You'd need an extremely well insulated box to get close.
The thing is that 20 times lower than the normal atmosphere is not a vacuum. For example, Mars has five times lower atmospheric pressure than in this vacuum chamber, but nasa's Ingenuity flew around there and did it very successfully
@@cutecats532 they're talking about the flying helicopter Ingenuity, meaning even at lower pressure w/ a large/fast enough propeller lift can be generated, there's still resistance
I use to clean and deliver for a machine shop. The had a wire edm machine I couldn't believe the tolerances they can cut too. It also blew my mind watching that super thin wire cut through material.
Kudos sir, somehow never thought about viscosity of air as even being a thing except in high speed vehicles 🎉🎉 rarely surprised these days, thank you sir.
My idea for the explanation of the syringe behavior would be that initially the pressure in the suringe is in fact much lower, but not much of it escapes, until it reaches a pressure where it does escape at around the same rate
I am very glad to have watched this video. I have always wondered how the thin atmosphere of Mars can carry so much dust, and I now understand that what the wind can pick up would be little dependent on air density.
I purchased 2 of these MetMo Cubes back when they were 500+ USD each and I LOVE them to this day :D They're now a lot cheaper, nearly half-off... WOW! Please consider purchasing your own you sooo won't regret it hahaa... i strongly believe in this company's products and want to see what else they come up with :D
Nah... we made light harvesting cones for far infrared cameras that way 25 years ago. Surface requirements were 20 micron precision. It's really impressive what wire-edm can do, but for a double entendre it's nowhere near new enough.
I appreciate your enthusiasm, but you were wise to hedge on the outcomes here, saying "what happens *may* surprise you". I was not surprised. Both experiments had the outcomes that I expected. Even when the vacuum chamber got down to 0.05 atm, the pieces of the cube eventually had *some* air rushing through the small gap to fill the vacuum space, resulting in the same effects we saw in air at 1 atm. In a perfect vacuum, such as on the surface of the Moon, I would expect the inner parts of the cube to slide out under gravity at about the same rate that the hammer and feather show when being dropped in the Moon's surface gravity, without interference. And for the syringe with the tiny tube, I figured molecules and particles in the air take up space and you can only get so many of them through the tube at any time, with a given particular pressure on the plunger. The pressure applied in the chamber hit that limit, so of course you got slowed down to the same speed as the plunger push in air.
For those not familiar, this is some rather nice looking EDM work. A lot of guys' EDM work would never fit together if you tried to keep the tolerances this close.
Everyone who guessed that it would just fall out is correct, however, it was not a perfect vacuum, if it were, the answer would apply. But still, the video was better, because I'd never guess even with less dense air it would react pretty much the same, so thanks again for free knowledge.
The title and the question is misleading. In perfect vacuum the pieces would fall fast, but in the experiment it wasn't even near perfect vacuum. The correct title would be "What Happens to Perfectly Fit Pieces of Steel In very low pressure?
Re read the title. It says “a vacuum” not a perfect vacuum. The point of the video was to showcase the viscosity of air at different pressures. Man y’all don’t pay attention.
@@istvanromai9603That is a theoretical vacuum, but that doesn't exist in nature, so real vacuums are assumed to be imperfect. Even so, @nahog99 is wrong here. When we refer to an (unqualified) vacuum in an experiment, we mean "low enough pressure to mostly eliminate air's effects on the experiment". In this situation, not enough air was removed to remove air's effect, so vacuum really was a misnomer. "Near vacuum" should have been used instead.
I've spent several years avoiding the urge to build a wire EDM machine. It's far more accurate than what I typically need for my hobby level machining, but it's so damned cool.
I would say part of the reason the pieces fall out fast then slow under vacuum is that the pieces are angled, so when they are most of the way out, gravity kind of bends the steel pieces against the walls.
I would expect a similar behavior but with 1/20th of the syringe travel left to go, as the plunger would have returned the pressure in the syringe to atmospheric.
Great video! Thank you. I never would’ve thought that the viscosity there would not change dramatically at lower pressures. I wonder if the designers of the Martian rovers take this effect into account? Considering that they have large vacuum chambers to play with I would imagine that they do, but it would be interesting to confirm that.
With these incredibly small orifices (first one being the gaps in the cube, second being the needle), you might also be getting choked flow after the fluid inside either the cube or syringe pressurizes. This would explain the rapid initial movement (fluid pressurizing), and then consistently slow movement afterwards (choked flow).
You held the metal up with a strong magnet. So wouldent those pieces also be magnetized, and hold together for that reason. And also the Eddy currents, could slow down the pieces as well.
If you put the thing inside vacuum as is, there will still be air on the inside. I think the pieces will be pushed up inside the vacuum chamber and behave normally for some time antil air escapes through the tiny gaps
I did figure it'd slow eventually. Though I'm wondering if you can somehow acquire and maybe fix up an old turbomolecular pump to get super hard vacuums to play with.
the reason it initially falls faster is because viscosity doesn't play a roll until the change in volume as a ratio accounts for the vacuum pressure of the environment. In a newtonian sense, the mass stops accelerating when the pressure acting on one side multiplied by its area minus the pressure outside acting on the same area multiplied by that area is equal to its weight.
This means that if the vacuume in the chamber was small enough that the difference between the outside and the inside even when the plunger traveled the full distance multiplied by the area was smaller than its weight, the viscosity of air wouldn't have an opportunity to stop its acceleration
If you removed the oxide layers on the surfaces of those metals while in a vacuum and try to slide the pieces in, they would cold-weld together as if they were always once piece of metal. Such is the nature of materials with a lattice of atoms.
How long did you pump the air out of the chamber? When I was an HVAC tech we would connect a vacuum pump to the system after doing certain repairs. The pressure in the system would drop quickly (depending on the size of it) then it would level off and then it would go up a bit then drop again. That little bump in pressure was usually water flashing off to vapor, which is exactly what we wanted to remove from the system. It could take hours to fully vacuum a system down and really big ones took a day or two. I wonder if vacuuming your chamber for an extended time would have any effect?
Think your exppanation of the syringe dropping is full of holes. It drops quickly at first until the pressure in the syringe increase and cancel out the weight. The air escaping through the needle is self limiting - the higher the pressure differential the more the molecues of air bump into each other and slow the flow. Not sure if that is the same as viscocity but I don't think it would happen with a pin hole instead of a needle (and viscocity is measured by liquid pooring through hole, not a nozzle.)
well timed, was just having conversation about this at work. had valve that was leaking through with argon really bad we thought it was completely broken but on xenon the leak almost entirely went away.
Friction between the EDM cut blocks could also be a factor when you let them slide out of the main block under "partial" vacuum. The blocks are initially sliding out fast. But as the blocks are cut at an angle the center of mass moves further away from where the hole is. This increases the friction force. As the blocks slide out further,, the forces at the contact points between the blocks and the main body get closer together which means the forces also increase because of this. Try to visualize the force vectors in the start condition and at the condition when the blocks are slid out almost completely. You will see the normal forces increase a lot and thus the friction forces increase. I'm not saying the low pressure situation isn't occuring. I'm just saying there are other factors at play
There's some friction, but how much? I'd think that it's fairly slippery. I'm inclined to think that the effect is minimal compared to the friction of the air molecules because the syringe shows the same speed reduction behavior, even though the plunger goes straight down. At least in the case of the syringe it's easier to imagine that at first most of the volume can be compressed more easily due to the reduced pressure, and once it reaches an air density similar to the one at 1 Atm it has to slow down as the air can't flow out of the needle any faster.
Definitely it will pull on both. At a decreasing rate at the vacuum chamber and compresor crankcase, are first at a +/-# and approach Equalize...... then very very very slowly gravity will take back over
What would be cool to try is sucking the air out of the vacuum chamber when the pieces are out.. maybe when it is on its side. I wonder if they would suck into the cube
in space metals weld themselves together . so i wonder if using gage blocks in a vacuum, can that happen? normally gage blocks are so smooth they will stick to each other in the regular atmosphere so under vacuum can you remove enough air molecules for them to weld together?
c. could it end up vacuum welding itself? given that the surfaces are really close together? edit: i was wrong, which id be wrong because there's an oxide layer, but the result was still really cool.
So if air can get in and out of that gap in the metal, how do glass syringes work? Those don't have a rubber seal, it's just glass on glass. They use them for certain chemical transfers and the like where any other material would contaminate the samples.
These observations are relative, and most of what we see here are tight zooms of a block that's been handled a lot and has some residue around the seams. The same is true on the vendor's website photos and video. At 40mm and more than half a kilo, it's still an impressive little thing to set eyes on, and the videos and photos probably don't do it justice, especially when it's new and/or clean. I'd compare this to when LCD and LED TV's came out, many people said it was like looking through a window. No, not even close, it was just a finer screen with higher refresh rates than the CRT's we had before, and most not as good as even the early smart phones. Everything's relative.
I think you said the metal parts are machined to just under .002" tolerance? How tight a tolerance would they need to be to see the caimir effect start to influence the pieces behavior? What would it look like if the casimir effect did start to influence thier behavior? Also, is each piece machined to a tolerance of .002" therefore making the added tolerance of the inside block and outside block a total of .004"? Or, is it a total of .002" tolerance between to 2?
Now redo the test after using a diffusion pump to get an ultra low vacuum. i’m certain when the vacuum is low enough the parts will drop in and out without speed reduction. Don’t forget to do the feather and marble drop test!
no matter how many air molecules are outside, only so many get through the seam. It's like a line of 100 people or 10,000,000 people, they still enter a building at the same rate.
Would you be able to "filter" the air in this way? By creating such a gap or holes that there would be more or less of a certain molecule testing their size or viscosity.
They didn't fall right out because they weren't in true vacuum. If you had stated in your original question that a little air would remain I would have assumed it would have some slowing effect.
I think the driving force of the air to move inside is lesser. The flow velocity maybe the same or maybe higher under vacuum but since the air is so thin, the amount of air going in is also decreased. The main equation to consider is below: Mass flow rate= density*flow velocity*area
Hmm that makes sense. Super fluids are used to get caffeine out of coffee beans because it goes through them like gas. So it must go through them with about the same ease as room temperature and pressure gas (at least when compared to a liquid.)
Another important thing is the transition between laminar flow and molecular flow. Although the pressure you created seems low from a human perspective, you still have billions of gas molecules per cubic centimeter with very short free travel paths, causing all the effects here. For the results you expected to see, you have to go down to like 10^-4 mbar with turbo molecular pump for example.
You called it "viscosity of air". But as the syringe took what little amount of air that was in the syringe and compressed it, once it reached the same density of "regular" air, it naturally slowed and emptied through the needle at the same rate. That is because the density equaled regular because the syringe was compressing the air. Am I right, or if not, what did I miss?
I thought for sure nothing would move. Less molecules and the addition of molecular drag (acting as a gasket between surfaces) would have slowed movement extremely.
Can you pull a vacuum and then fill the charmer with hydrogen to 1 atmosphere of pressure. As its the smallest molecule will it allow for a deferent result?
One correction - the pieces are cut separately to very high tolerance - you can't cut a single piece to get that result.
Yeah, there is material loss, at a minimum it's the width of the cutting wire.
Thank you. How would you cut the bottoms if they were one piece? I suppose it's possible they used an EDM wire to drill the pass-through, but that could easily have been done with a regular drill and a plug.
I guess they cut the pieces from the original cube like all the way through and closed the holes with a lid held by screws. You can see it at 1:56
@Tb0n3 there has to be a hole to feed the cutting wite through - and of course the wire itself makes a gap. Once the pieces are assembled the sides are milled - so the joins become impossible to spot.
@@williamdetempolivre no they're cut completely separately - to incredible tolerance - then machines so the lines are more or less invisible.
Just to be clear...
The "slugs" in that block were NOT cut from "that" block. They were cut from a second block and fitted to the cavities of the first.
The kerf (waste) of the wire EDM process is ~0.013" (0.33mm) per side.
A tool maker might say, that's like throwing a hotdog down a hallway.
The kerf depends mostly on the diameter of the wire used. There are different sizes of wire for a wire edm.
I'd love to see that process on this channel
@@theboxofdemons
Obviously, but the important part is the general order of magnitude
0.013"? If that was typical these days for wire EDM, it would be worthless for the cost. I get your point, but the inserts are way tighter tolerance than 0.013" on the perimeter.
@@PioneerRifleCompany it has nothing to do with tolerance. They are talking about the cut width itself.
I love seeing how he figures out how to interact with stuff inside the vacuum chamber
102 likes and zer orpeklleis ?!?!?!? lemt sne dj d djd
How nice it must be looking at the problems of the world for a sol'n and being able to think, "Lasers, mthrfkrz!"
@@NotSoMuchFranklyjust look at Styropyro.
I'm pretty sure he's put everything in his house that will fit into his vacuum chamber. He just shows us the interesting ones
I thought the metal would cold weld together in a true vacuum, is that wrong?
I just did the math. The absolute pressure is about 5000Pa in the chamber. This means if the absolute pressure created inside the block is approximately 0, the maximum force based on a 1"x0.5" plunger is about 0.34 pounds, which is most definitely more than the weight of one of those blocks. Very cool!
What
my immediate thought before watching the video was cold-welding.
Same! But maybe only if it was gold/gold plated
Same
@@It-b-Blair I'm pretty sure this was a problem in space with some equipment, so it can happen to other materials but it needs to be a clean surface. Probably this cube has a coating that prevents cold welding, such as stainless steel or aluminium gets naturally to prevent corosion.
That is my thought and i have not watched yet
@@tortex1 no need for a coating. all metal exposed to the earths atmosphere will quickly develop a thin layer of oxide that prevents cold welding. If you scratch off this oxide layer in space, the lack of atmosphere prevents the oxide layer from reforming, and cold welding at that spot is possible
This is a very interesting video. I was surprised to see that the metal parts only fell out a little faster under vacuum. However, I was thinking a "full" vacuum, and now I realize that the vacuum wasn't very strong. I would really like to see the experiment with even stronger levels of vacuum!
However, I think you might have missed that the reason the plunger of the syringe falls faster in the beginning is that there is less pressure inside of the syringe, however as the plunger falls, the relative pressure between the syringe and the pressure inside of the needle itself begins to even out, so in fact, there is more pressure inside of the syringe as it gets closer to the needle.
Definitely, I was thinking about that too
Perhaps astronauts can bring this experience on moon
In full vacuum the pieces would weld together.
@@rhettbaldwin8320is there any particular reason you say that? Because with my limited knowledge on vacuums and materials it seems just as likely that they slide apart as fast as possible when accounting for friction. So I’m curious if you have anything academic to teach me what happens
@@rhettbaldwin8320 Very Interesting.
Depends on how long you keep them in the vacuum. Right away they probably move fast since air pressure stops being a factor. But over time - not sure how long - the oxidation layer will wear off and they will contact weld to one another and seize up. This is a problem spacecraft run into, and they require special lubricants to solve it.
I clicked on this video expecting it to be about welding.
@@yairlll me too XD! I was thinking 'well, the surprising effect in vacuum will be that the block will stick'!
@@andremariaribeirodacunha3695 I remember this issue from the Gemini "space walks". The hatch was somewhat uncooperative.
i thought the same but he doesn't get enough vacuum and his surfaces are not smooth enough possibly. i suggest gage blocks stuck together as they stick to each other because they are so smooth.
His vacuum is several orders of magnitude off from achieving cold welding, or stripping metal oxide layers. I had the same thought before the video started though.
How about backfilling the chamber with a small-molecule gas like hydrogen or helium?
That sounds like a neat experiment. Would adding "something" (a low viscosity gas) actually decrease the viscosity of "nothing" (a partial vacuum)? It would seem counterintuitive for that to happen, but given that 0.05 atm is far from "nothing", seeing how different gases interact with one another with respect to viscosity would be interesting.
@@mattp422 that sort of thing would be very useful for something like studying aspects of the high atmosphere.
I can see issues arising filling a chamber with hydrogen and some residual air then using a laser to burn a string in it ...
He atoms. H molecules. H would be similar to air since its around the same size molecule as airs components. Any Noble gas would be way smaller than H. Good idea, tho.
Or cooling down the air a lot to reduce the viscosity
I like how he casually says "I'm going to cut the string with my laser" like this is a completely normal thing that everyone can do...
backyard scientist has some powerful lasers and there's styropro as well
I just did a ctrl+f to search for this comment
The average person who has a vacuum chamber that big probably does also have a laser that could do this. Similar people tend to like similar toys.
Are you saying you don't have a high power laser in your house?? In all seriousness it is pretty funny how casual he is
@@PatGames111 sigh, no...
One other thing to consider is the dynamics of flow through a pipe. Flow rate is determined by delta pressure (and viscosity which, as noted, is usually constant). Since this pipe is so tiny, it has a very small maximum flow rate, and therefore a very small delta pressure. Since delta pressure doesn't care about ambient pressure, the flow rate through the pipe is the same, whether or not ambient pressure is super low or super high. If there are enough molecules to generate a delta P, the syringe will always fall at the same rate.
Counterintuitively, many properties of ideal gases depend only on temperature and are independent of pressure: enthalpy, viscosity, speed of sound to name a few. Interestingly, both viscosity and speed of sound are both proportional to the square root of the absolute temperature. Yes, viscosity of gases INCREASES with temperature as the mechanism of viscosity is totally different than in liquids (momentum transfer between layers which occurs faster the faster the particles of the gas move)
I think the effect we see here is also related to soda outgassing. It doesn't matter how much air you pump into an open soda bottle, it will still go flat at almost the same rate as if it were at outside pressure. The only solution is to pump in the same gas, carbon dioxide, into the bottle.
Absolutely love your videos! I've seen these perfectly machined steel things before, but it's really cool what you tested with the vacuum for it! Love your fresh experiments!
Your videos never cease to amaze me! That's not what I expected and I have to say, is still counterintuitive to me! Your explanation of the gas molecules slipping past one another kinda makes sense though.
1:12 I really appreciate seeing someone finally handle these like a normal person. With all of the jitter and imperfect human movement that videos of these machined parts usually refuse to show, since all of them want to be "satisfying".
This really helped me understand this a bit better and in turn was MORE satisfying
1:26 NOOO I CAN SEE THE GAP
I worked on a laser tube cutter years ago, that used finely ground parallel metal surfaces in a vacuum to generate the beam.
I was told that those surfaces were ground so flat that if they ever came together you would never get them apart.
@5:55 The cube is moving down in the same way on both sides, so the net force on the cube should be the same. Yet the reported pressure difference between the inside and outside of the syringe is different--it's a higher delta in the vacuum by a significant fraction. The only other factor I can think of is the buoyant force of air on the cube, is that enough to explain the increased "weight" of the cube on the right? And given this increase in deltaP, is it really fair to call the viscosity equal between the two scenarios?
Wow, James I love how you figure out the tricks you need to use to manipulate things when you have to interact through a wall, such as part of the vacuum chamber!
Cool!! I was hoping for some space cold welding… Could you try clamping two close fitting metal surfaces together in a vacuum and running a test of DC voltages through them to see what happens?
@@nagjrcjasonbower Cold welding required a vacuum several orders of magnitude more empty than what he's using here. It also requires materials that are very clean, including of oxide layers. Gold is easy to cold weld, stainless steel is pretty difficult and usually requires some mechanical abrasion while in the vacuum to expose the bare metal.
@@jasexavier Cool! I wonder if his pump can handle a vacuum close enough…😎 Mine only goes to Mars surface pressures…
@@nagjrcjasonbowerdefinitely can't handle low enough pressures lol, you'd have to have some insane vacuum pumps to get it as low as you need.
I definitely wasn't expecting the viscosity to plateau like that. I wonder if there's a macroscopic scale demonstration that could show why that plateauing happens?
Well it happens because its not a true vacuum. In a true vacuum it would just fall out instantly
The reason this happens is because of pressure differential. Eventually, the small gap allows the inside and outside pressures to equalize and the assembly behaves the same as at room atmospheric pressure. An absolute vacuum, like absolute zero temperature. is impossible to achieve.
@@peteroleary9447it's like amount of particles per volume you can get it extremely low though. If it's 1 particle per m³ it's not too bad. 1 part per nm³ and it's a much less useful vacuum.
Temperature is similar, you try to stop all the atoms but outside stuff tries to bump into it and everything tends to jiggle, and there's radiation that makes things jiggle. You'd need an extremely well insulated box to get close.
@@peteroleary9447 it wouldn't have to be a perfect vacuum. Eventually there just wouldn't be much air in the way. Like in space.
@@peteroleary9447 well in near perfect vacuum like in space,it would just fall out, there isnt pressure to hold it back
@@Bishox Space is not perfect vacuum. Didn't you know that in space there is stuff? Things like earth.
The thing is that 20 times lower than the normal atmosphere is not a vacuum. For example, Mars has five times lower atmospheric pressure than in this vacuum chamber, but nasa's Ingenuity flew around there and did it very successfully
What does traveling around Mars have to do with a vaccum?
@@cutecats532 atmospheric pressure..
Depending on the field the word "vacuum" has different definitions. Often it's just defined as lower pressure than the surrounding area
@@cutecats532 they're talking about the flying helicopter Ingenuity, meaning even at lower pressure w/ a large/fast enough propeller lift can be generated, there's still resistance
Vacuum doesn't mean 0,00....
I use to clean and deliver for a machine shop. The had a wire edm machine I couldn't believe the tolerances they can cut too. It also blew my mind watching that super thin wire cut through material.
0:57 this could almost be used as an 'hourglass'
Kudos sir, somehow never thought about viscosity of air as even being a thing except in high speed vehicles 🎉🎉 rarely surprised these days, thank you sir.
My idea for the explanation of the syringe behavior would be that initially the pressure in the suringe is in fact much lower, but not much of it escapes, until it reaches a pressure where it does escape at around the same rate
Very interesting demo and yes, I did get it pretty much right. I'm a bit surprised that the slowdown at low pressure was as much as it was though.
This guy somehow consistently always find interesting videos to make🔥🔥 good stuff man🎉
How did they machine the connected channel for the cube 0:19
Huh?
Grammar? Where did you go? * echos *
@@whiffingherbsWdym? This is a perfectly grammatically correct sentence.
@@NovaSuperSuper correct, you wrote a gramatically correct sentence
@@whiffingherbs The OP did too.
1:04 what if you lubricate the pieces so that the tiny gap is filled?
i think the lube 'd just take place of the air, it moving slowly in/out due to pressure
I am very glad to have watched this video. I have always wondered how the thin atmosphere of Mars can carry so much dust, and I now understand that what the wind can pick up would be little dependent on air density.
I purchased 2 of these MetMo Cubes back when they were 500+ USD each and I LOVE them to this day :D They're now a lot cheaper, nearly half-off... WOW! Please consider purchasing your own you sooo won't regret it hahaa... i strongly believe in this company's products and want to see what else they come up with :D
Excellent question, surprising answer.
One of your most fun!
Since you're the scientist and my guess was the same as yours, I call it a win. I may not have been right but have a W!!! Thanks for what you do.
Your vacuum chamber deserves his own channel. "Thousand ways of using a vacuum chamber" achived
Now that is some *cutting edge* technology
Nah... we made light harvesting cones for far infrared cameras that way 25 years ago. Surface requirements were 20 micron precision. It's really impressive what wire-edm can do, but for a double entendre it's nowhere near new enough.
@@wernerviehhauser94-->cutting edge technology
I appreciate your enthusiasm, but you were wise to hedge on the outcomes here, saying "what happens *may* surprise you". I was not surprised. Both experiments had the outcomes that I expected.
Even when the vacuum chamber got down to 0.05 atm, the pieces of the cube eventually had *some* air rushing through the small gap to fill the vacuum space, resulting in the same effects we saw in air at 1 atm. In a perfect vacuum, such as on the surface of the Moon, I would expect the inner parts of the cube to slide out under gravity at about the same rate that the hammer and feather show when being dropped in the Moon's surface gravity, without interference.
And for the syringe with the tiny tube, I figured molecules and particles in the air take up space and you can only get so many of them through the tube at any time, with a given particular pressure on the plunger. The pressure applied in the chamber hit that limit, so of course you got slowed down to the same speed as the plunger push in air.
I expected the video about cold welding, when I clicked. But this is fun, too.
Love how nonchalantly you cut the string with a laser, like that’s something we do every day.
For those not familiar, this is some rather nice looking EDM work. A lot of guys' EDM work would never fit together if you tried to keep the tolerances this close.
Seriously cool.
Ofc
agreed
I’ve never wondered this but now I want to know the answer
@@Gummybear7koolaid that’s honestly exactly how I felt, as well, lol!
He explains better than my teacher 💯
Everyone who guessed that it would just fall out is correct, however, it was not a perfect vacuum, if it were, the answer would apply. But still, the video was better, because I'd never guess even with less dense air it would react pretty much the same, so thanks again for free knowledge.
The King of Vacuum Chambers 👑
:)
Bro really loves his vacuum chamber
It's cool how you learn something new with us. So it's true that we never stop learning even if you have PhD.
The title and the question is misleading. In perfect vacuum the pieces would fall fast, but in the experiment it wasn't even near perfect vacuum. The correct title would be "What Happens to Perfectly Fit Pieces of Steel In very low pressure?
“Nearly perfect fit pieces”… nothing is perfect
Let's hear your definition of perfection? Not what Google says we want your definition...
Re read the title. It says “a vacuum” not a perfect vacuum. The point of the video was to showcase the viscosity of air at different pressures. Man y’all don’t pay attention.
@@nahog99
Dude, in sciences vacuum means space devoid of any matter, the latin word itself means void. You didn't pay attention in physics class.
@@istvanromai9603That is a theoretical vacuum, but that doesn't exist in nature, so real vacuums are assumed to be imperfect.
Even so, @nahog99 is wrong here. When we refer to an (unqualified) vacuum in an experiment, we mean "low enough pressure to mostly eliminate air's effects on the experiment". In this situation, not enough air was removed to remove air's effect, so vacuum really was a misnomer. "Near vacuum" should have been used instead.
AMAZING and counterintuitive ! Thanks!
I can't believe I got this right from pure intuition, there must have been something I remembered that made me get this right lol
I've spent several years avoiding the urge to build a wire EDM machine. It's far more accurate than what I typically need for my hobby level machining, but it's so damned cool.
I would say part of the reason the pieces fall out fast then slow under vacuum is that the pieces are angled, so when they are most of the way out, gravity kind of bends the steel pieces against the walls.
Very interesting episode, impressive work!
Here is my guess : You created an experiment that would allow you to use a laser to cut a string.
Love your work.
He’s done it before. He’s good with Macguyvering.
1:40
I think that if you put it in pressured, it will first push the blocks out. Then it will slide quickly. There is a chance of a cold weld though.
I would expect a similar behavior but with 1/20th of the syringe travel left to go, as the plunger would have returned the pressure in the syringe to atmospheric.
Keep it up. This is a great channel.
Great video! Thank you. I never would’ve thought that the viscosity there would not change dramatically at lower pressures. I wonder if the designers of the Martian rovers take this effect into account? Considering that they have large vacuum chambers to play with I would imagine that they do, but it would be interesting to confirm that.
With these incredibly small orifices (first one being the gaps in the cube, second being the needle), you might also be getting choked flow after the fluid inside either the cube or syringe pressurizes. This would explain the rapid initial movement (fluid pressurizing), and then consistently slow movement afterwards (choked flow).
Action Lab is slowly becoming Vaccuum Lab... and I'm all for it
You held the metal up with a strong magnet. So wouldent those pieces also be magnetized, and hold together for that reason. And also the Eddy currents, could slow down the pieces as well.
If you put the thing inside vacuum as is, there will still be air on the inside. I think the pieces will be pushed up inside the vacuum chamber and behave normally for some time antil air escapes through the tiny gaps
If you had a perfect vacuum, would it fall out fast?
I did figure it'd slow eventually. Though I'm wondering if you can somehow acquire and maybe fix up an old turbomolecular pump to get super hard vacuums to play with.
the reason it initially falls faster is because viscosity doesn't play a roll until the change in volume as a ratio accounts for the vacuum pressure of the environment.
In a newtonian sense, the mass stops accelerating when the pressure acting on one side multiplied by its area minus the pressure outside acting on the same area multiplied by that area is equal to its weight.
This means that if the vacuume in the chamber was small enough that the difference between the outside and the inside even when the plunger traveled the full distance multiplied by the area was smaller than its weight, the viscosity of air wouldn't have an opportunity to stop its acceleration
If you removed the oxide layers on the surfaces of those metals while in a vacuum and try to slide the pieces in, they would cold-weld together as if they were always once piece of metal. Such is the nature of materials with a lattice of atoms.
Hmm, not likely. Many everyday items have assemblies that are interference press-fit together. They don't cold weld.
i like the new editing
How long did you pump the air out of the chamber? When I was an HVAC tech we would connect a vacuum pump to the system after doing certain repairs. The pressure in the system would drop quickly (depending on the size of it) then it would level off and then it would go up a bit then drop again. That little bump in pressure was usually water flashing off to vapor, which is exactly what we wanted to remove from the system. It could take hours to fully vacuum a system down and really big ones took a day or two.
I wonder if vacuuming your chamber for an extended time would have any effect?
1:13 That satisfying pop!
Think your exppanation of the syringe dropping is full of holes.
It drops quickly at first until the pressure in the syringe increase and cancel out the weight. The air escaping through the needle is self limiting - the higher the pressure differential the more the molecues of air bump into each other and slow the flow.
Not sure if that is the same as viscocity but I don't think it would happen with a pin hole instead of a needle (and viscocity is measured by liquid pooring through hole, not a nozzle.)
well timed, was just having conversation about this at work. had valve that was leaking through with argon really bad we thought it was completely broken but on xenon the leak almost entirely went away.
Very interesting segment. Wondering where you would apply this theory to either everyday life or a career?
Yell us more about the laser you used to cut the string. Can that shine through paint or walls?
Friction between the EDM cut blocks could also be a factor when you let them slide out of the main block under "partial" vacuum. The blocks are initially sliding out fast. But as the blocks are cut at an angle the center of mass moves further away from where the hole is. This increases the friction force. As the blocks slide out further,, the forces at the contact points between the blocks and the main body get closer together which means the forces also increase because of this. Try to visualize the force vectors in the start condition and at the condition when the blocks are slid out almost completely. You will see the normal forces increase a lot and thus the friction forces increase. I'm not saying the low pressure situation isn't occuring. I'm just saying there are other factors at play
There's some friction, but how much? I'd think that it's fairly slippery. I'm inclined to think that the effect is minimal compared to the friction of the air molecules because the syringe shows the same speed reduction behavior, even though the plunger goes straight down. At least in the case of the syringe it's easier to imagine that at first most of the volume can be compressed more easily due to the reduced pressure, and once it reaches an air density similar to the one at 1 Atm it has to slow down as the air can't flow out of the needle any faster.
Definitely it will pull on both. At a decreasing rate at the vacuum chamber and compresor crankcase, are first at a +/-# and approach Equalize...... then very very very slowly gravity will take back over
I loved this episode!
What would be cool to try is sucking the air out of the vacuum chamber when the pieces are out.. maybe when it is on its side. I wonder if they would suck into the cube
in space metals weld themselves together . so i wonder if using gage blocks in a vacuum, can that happen? normally gage blocks are so smooth they will stick to each other in the regular atmosphere so under vacuum can you remove enough air molecules for them to weld together?
1:47 B because I think it’ll vacuum the pressure and will fall straight down with a slow fall at the end for the rest of the air
Trying this in different temperatures would be neat. I don't know how you would get around the problem of heat deforming the metal or maybe a syringe?
c. could it end up vacuum welding itself? given that the surfaces are really close together?
edit: i was wrong, which id be wrong because there's an oxide layer, but the result was still really cool.
So if air can get in and out of that gap in the metal, how do glass syringes work? Those don't have a rubber seal, it's just glass on glass. They use them for certain chemical transfers and the like where any other material would contaminate the samples.
You can see, you just likely wouldn’t notice unless you were looking for them
Edit: at 1:25 though it is really very noticeable
I wasn’t looking for them and I noticed instantly at 0:25
These observations are relative, and most of what we see here are tight zooms of a block that's been handled a lot and has some residue around the seams. The same is true on the vendor's website photos and video. At 40mm and more than half a kilo, it's still an impressive little thing to set eyes on, and the videos and photos probably don't do it justice, especially when it's new and/or clean. I'd compare this to when LCD and LED TV's came out, many people said it was like looking through a window. No, not even close, it was just a finer screen with higher refresh rates than the CRT's we had before, and most not as good as even the early smart phones. Everything's relative.
I think you said the metal parts are machined to just under .002" tolerance? How tight a tolerance would they need to be to see the caimir effect start to influence the pieces behavior? What would it look like if the casimir effect did start to influence thier behavior? Also, is each piece machined to a tolerance of .002" therefore making the added tolerance of the inside block and outside block a total of .004"? Or, is it a total of .002" tolerance between to 2?
Now redo the test after using a diffusion pump to get an ultra low vacuum. i’m certain when the vacuum is low enough the parts will drop in and out without speed reduction. Don’t forget to do the feather and marble drop test!
no matter how many air molecules are outside, only so many get through the seam. It's like a line of 100 people or 10,000,000 people, they still enter a building at the same rate.
Would you be able to "filter" the air in this way? By creating such a gap or holes that there would be more or less of a certain molecule testing their size or viscosity.
You could test the flow rate with that cube by filling the vacuum chamber with different gasses to test different viscosities
Hats of to Physics... and this damn cool presentation
They didn't fall right out because they weren't in true vacuum. If you had stated in your original question that a little air would remain I would have assumed it would have some slowing effect.
Can you do a video on the transparent double sided tape you used to stick the metal block to the turntable? It has some interesting features.
I think the driving force of the air to move inside is lesser. The flow velocity maybe the same or maybe higher under vacuum but since the air is so thin, the amount of air going in is also decreased. The main equation to consider is below:
Mass flow rate= density*flow velocity*area
Hmm that makes sense. Super fluids are used to get caffeine out of coffee beans because it goes through them like gas. So it must go through them with about the same ease as room temperature and pressure gas (at least when compared to a liquid.)
Now if the surface oxidation (if any) is removed, will the vacuum make them cold-weld?
Another important thing is the transition between laminar flow and molecular flow. Although the pressure you created seems low from a human perspective, you still have billions of gas molecules per cubic centimeter with very short free travel paths, causing all the effects here. For the results you expected to see, you have to go down to like 10^-4 mbar with turbo molecular pump for example.
If you clean it really well and leave it in the vacuum for a few days, will it cold weld?
Did the Metmo Cube's interior have time to come to equilibrium with the vacuum chamber's air?
So at what rate can you introduce/compress the air and keep the pieces from falling out? 😆
Quick question, what is stopping the metal from cold welding to itself?
You called it "viscosity of air". But as the syringe took what little amount of air that was in the syringe and compressed it, once it reached the same density of "regular" air, it naturally slowed and emptied through the needle at the same rate. That is because the density equaled regular because the syringe was compressing the air.
Am I right, or if not, what did I miss?
That's what I thought.
What if the pressure in the vacuum tank goes even lower?
I'd suspect the syringe would slow down later, if at all.
I thought for sure nothing would move. Less molecules and the addition of molecular drag (acting as a gasket between surfaces) would have slowed movement extremely.
Can you pull a vacuum and then fill the charmer with hydrogen to 1 atmosphere of pressure. As its the smallest molecule will it allow for a deferent result?