How Does The Anti-Gravity Wheel Work?

[@cleon_teunissen]

On why the scale does not show the peak value when the disc bounces at the end of its tether: I assume the processor of the display is programmed to display an *average* over some time interval, probably half a second or so. Without that smoothing the value in the display would jump all over the place, making it unreadable. So the fact that the display does not show the short duration peak value is not due to 'slow refresh rate', I think. I think the processor may even be programmed to discard short duration peaks.

[@CharlieKellyEsq]

Then why is it always at - weight. Even if it the scale is taking an average force over time, the average should be around 0, not -6

[@cleon_teunissen]

@@CharlieKellyEsq Let me quote what I wrote an hour ago: "I assume the processor of the display is programmed to display an average over some time interval, probably half a second or so." I estimate that it takes the weight 3 seconds or so from release to the end of its tether. That is *several times longer* than what I gave as a guess for the duration of the averaging window. Whatever the actual duration of the averating window is, clearly it is short enough so that the scale has opportunity to show a readable value of around -6

[@CharlieKellyEsq]

@@cleon_teunissen I see, you're a nerd

[@chitlitlah]

I doubt it. A scale like this isn't really intended to weight things that are bouncing around. You're assuming it uses a relatively complex algorithm to average out a lot of samples taken between updates and tosses out short duration peaks which it would have to do for the display not to increase when the weight bounces (but then what's the point of taking an average if you're going to toss out samples?) when it would be a lot simpler just to take a sample before every update. As long as the thing you're weighing isn't bouncing around, there's not much point in averaging multiple samples.

[@Philociraptor]

At 7:57 he talks about the spike of force when it reaches it at the bottom.

[@anthonylangley8717]

I’m glad there are people who can use their brain power to figure out stuff like this, thereby freeing up my time so I can do stuff like mow the lawn and do the dishes.

[@babybirdhome]

You always come up with tons of amazing content for your channel, but this simple demonstration really drove home a fundamental concept that I only now realize at 49 years old that I had never actually understood. That is phenomenal work!

[@stolearovigor281]

Have you realize that gravity doesn't exist?

[@3DPeter]

This is old school science that i already learned when i was 5! Take a bicycle wheel and try to hold it up at one side of the centre axle. You won't be able to hold it upright but as soon you spin the wheel, you can hold it up with only the tip of your finger. The reason why you can hold it then is because the centrafugal force moves in all directions so the wheel wants to move in all directions. there's even a guy that has a large and real heavy metal wheel on an axle and you can't lift that up with one hand, let alone lift it up above your head, but as soon the wheel is spun around, the whole thing weighs almost nothing and then you can swing it with ease above your head.

[@jcmschott1895]

@@3DPeter, when you were 120 years old? OMG! How old are you?

[@3DPeter]

@@jcmschott1895 ????? where do i say that i'm 120 years old?

[@jerrywiessner]

@@3DPeter Use of gyroscope action 120yrs ago.

[@mikefochtman7164]

Another little side measurement. If you put a couple of reflective 'dots' on the rim of the disk and use a high speed camera, we could see that the disk rotation is also constantly accelerating. If the system was made taller and 'fins' added to the disk, you could reach a point where its rotation stops accelerating (and therefore it's downward acceleration zeros). At this point, the scale should return to zero even though the disk is still moving upward/downward. So you might have a negative weight shown as it starts to fall, weight returning to zero when the disk isn't spinning any faster, and that positive 'spike' at the bottom of travel when the disk 'bounces'.

[@jcmschott1895]

Nice one, dude! I did some calculations here and if I am not wrong, the angular acceleration is, roughly speaking, proportional to the r radius of the rod and inversely proportional to the mass and the square of the disc radius R. So, for a large disc, maybe you can capture the image with a smartphone camera and analyse the footage with a software called Tracker Motion Analysis. It's for free.

[@Observ45er]

That acceleration is an important clue to what's happening. The mass of the wheel is effectively bouncing under partial gravity - not in free-fall like a ball, or a person on a tramp, but with an additional effect (transfers of energy) that reduced the effect of gravity allowing it to 'bounce' at less that 1 g.. . It's a real brain-burner, but pretty cool and really causes / requires serious thinking and a darn good understanding of physics..

[@shauryasingh1685]

is the same thing used in a YOYO

[@isaac7984]

Nope, you're wrong. I checked the math

[@fridaycaliforniaa236]

You should show it with an old scale (mechanical). We should see the thing bounce a bit at the bottom =)

[@two_number_nines]

no, old scales have too much mass and inertia and would filter out any small spikes in force.

[@adityaparab3677]

the wheel bouncing at the bottom will kill the kinetic energy n inertia by the friction depended on the surface just like you spin rear wheel of a cycle in air n drop it causing it to stop completely

[@wilhelmbeck8498]

@@two_number_nines In some cases, an analogue scale will do the job better.

[@fridaycaliforniaa236]

@@two_number_nines Oh, ok... ^^

[@emmanuelpil]

Just a simple calculation. If the effect of lowering the wheel during 3 seconds is -6 grams; in a bouncing spike of let's 1/10 of a second you would feel a 'weight pulse' of 30*6 = 180 grams. Thats a whole lot It should be visible somehow, but even playing the video in slow motion I don't see any movement(shock) of the balance indicating this

[@AirGunScientist]

Great video. So the simple point is regardless of the direction, the A-G wheel is accelerating downward. I.e. when falling it is ACCELERATING downward, when rising, it is DECELERATING upward. (both a net acceleration in the down direction). Not intuitive at first, but your explanation shows why. TBH, I would NEVER have guessed that. It wasn't intuitive to me. Thanks again Joe Brancato THE AIRGUN SCIENTIST

[@harleyquinn8202]

"wheel is accelerating downward" - except when it "bounces" at the bottom

[@Chrmel0]

How about in a vacuum? It would be cool to see how much longer it will last.

[@mike1024.]

The acceleration I believe would be the same, but I wonder if the friction of the wires around the object is what's really slowing it down instead of air resistance? Hard to say until he tries!

[@aluiziofjr]

My guess is that it won't be much different. The sound loss is already minimum and so is the air resistance since it's a round object

[@blazingguyop]

Little bit more

[@deletedaccount573]

You would get the almost same result bcoz friction uses most of energy(not air) here but with out friction it wouldn't spin like that due to no friction in btw wheel and string....! And in zero gravity I think it would be different...

[@30caratteri]

Agreed, Mr. Phoenix

[@jacobwcrosby]

You need an analog scale for this. Or a scale with a much faster update speed.

[@ExoticAnimation]

maybe

[@robbiebouchart1551]

Start building a spaceship

[@555104068]

Ye guess there is an Gravity spike when the Disk is at the lowest Point. Digital Skale is just to Slow

[@stanleybochenek1862]

try 2x speed

[@carsoncraytor9920]

It would be cool if it was a faster scale that could output its data into a line graph

[@heisag]

I used this concept to accelrate a flywheel horizontally, and made an action drive by having it bounce/crash into the interior wall of an vehicle at the end of its stroke , transfering the forward momentum of the flywheel into forward motion of a vehicle. It worked since this method of accelrating a flywheel forward seemed to have very little recoil. In fact, i didn't notice any recoil, but that might have been due to friction in the wheel bearings (lego). It wasn't very effective though, in terms of energy input and forward motion. I used rack and pinion at first, with no rack at the end of the stroke. After that, i used spring loaded strings through the axle. Though, i didn't go as far as motorize it. That was half a year ago , and i haven't really looked too much into it. Was suspecting that accelrating a flywheel would reduce it weight, so it was nice to see a video that confirms it.

[@thumper88888]

In a project book from the ‘60s was a similar toy, rolling a BB around in a film can. On a ramp. The impact moved the box forward overcoming the box/table friction but the rear movement was absorbed by internal friction.

[@heisag]

@@thumper88888 Thank you. I decided to finally release the video i made of it, poor video, but a picture is worth a 1000 words. It is not meant as self-promotion, although i could see it technically be just that. This beeing hidden away deep down a youtube comment section anyway. Something are just difficult to describe with words alone.

[@johnnyragadoo2414]

Nice food for thought. The wheel is in some fraction of free fall when moving down - and also when moving up. Free fall doesn't mean getting closer to the ground.

[@eb4661]

Very cool! (The “missing” grams on the positive side of scale is collected in the knock when direction change at the bottom - just like one feels operating on a yo-yo.)

[@tactileslut]

In the yoyo style this project looks perfect for simulating perpetual motion.

[@ImYourProblem]

Those missing grams are collected when the disk is wound and elevated back up to it's starting position lol.

[@eb4661]

@@ImYourProblem No. The grams are missing both up and down(!) They are in fact collected in a knock at the bottom.

[@carultch]

@@eb4661 They would be collected in the knock at the bottom, but that knock at the bottom is in a blindspot of the scale's signal processing capabilities. If you could measure with infinite precision, you'd get an average force of zero in the scale, between equivalent points in the cycle.

[@alansmithee419]

so is it the case that: loss of weight in air * time in air = gain in weight at bottom * time spent turning around at the bottom?

[@richardperry100]

The full expanation is correct. In effect from the moment the disc is released until it finally come to rest, it is effectively losing energy by acceleration downwards and the upward movement is decellerating as it goes up i.e. still accelerating down. Nothing to do with the disc spinning - it will do the same with a weight hanging on a spring.

[@nirodha7028]

I love the explenation that it is excellerating downwards even when it is moving upwards 👌🏻

[@Atzanteol1]

But it's *always* accelerating downwards. Even when it's stopped.

[@samedy00]

@@Atzanteol1 no, at the very bottom it's accelerating upward.

[@billfranks6805]

Thank you I've learnt something today please keep your videos coming I really enjoy learning this way

[@sudanamaru]

Fantastic! The wheel is under partial free fall all the time except it momentarily bounces from the bottom.

[@rosone51178]

I would think with really precise measurements all the forces would cancel out, 10 total seconds at -6 would mean 1 total second at +60, or something to that effect. The refresh rate on the scale didn't show the positive wieght spike because it was only for such a short time.

[@thierryfaquet7405]

And you would think wrong. Which is ok as long as you understand it being wrong.

[@eekee6034]

Seems reasonable; we know that impacts increase force at the expense of time. A bouncing ball would impact the scale. The sudden change in the wheel's direction looks like an impact. Maybe it is, maybe the rotation modifies it. It would be interesting to find out how the characteristics of the strings affect it too. A chart-recording scale would be really useful.

[@ivarangquist9184]

@@thierryfaquet7405 Would you please elaborate?

[@thierryfaquet7405]

@@ivarangquist9184 just watch the video ???

[@flipschwipp6572]

Your thought is exacly right, in the bottom the direction of movement is changing,the whole mass of the flywheel has to be accelerated from downwards motion to upwards motion, the cables get a short peak force they transfer through the contraption, which the scale does not show.

[@cplatter38]

"My wife is my safety inspector" .... brother... that killed me!! That's awesome!!

[@ooooneeee]

"Due to some undisclosed incidents" 😂

[@f-xdemers2825]

In this case the "Acceleration is always downward" In those simple words lies the entire explanation. Thanks.

[@ikocheratcr]

Interesting effect, first to me. In case you want a higher sample rate for the scale, there is a very simple option with an arduino ($5), an HX711 ($5) module and a weight sensor ($5~$20). Then on arduino interface you can plot it directly from serial port data. HX711 can sample at 10samples/s or 80samples/s configurable.

[@jcmschott1895]

Hey, mate! Is it possible to save it to a file?

[@therealdebater]

I'd love you to now do an energy analysis of this system. Very often an energy analysis can reveal or clarify many of the weird phenomena of physics. The maths is complicated (for the layman), but the principles are straightforward, so it would be really valuable for a video like this to present the concepts in a more approachable way. A big ask, I appreciate.

[@descendantofgreeksandroman2505]

You are close to explain it! The rolling of the disk is extrernal energy that he added to the system. The rest I believe are transformatios of energy and momentum/force/mass relations. Its not a miracle, is explainable (but I have to recall my gymnasium physics)

[@jesseluna4406]

Would have been nice to see the extra weight it had as it bounced back up. Maybe even showing a chart of the -6g and the spiked positive weight when it bounces. I wonder if that could be shown well with a mechanical scale.

[@AlexGeek]

I think it would be an infinite weight during an infinitely small amount of time.

[@Sonny_McMacsson]

@@AlexGeek Not in reality

[@carultch]

@@AlexGeek Only in the oversimplified world of introductory physics, where rigid bodies are truly rigid and inextensible strings exist. The truth is, all strings, cords, cables, etc, will have some degree of stretching, and due to this, the spike at the bottom will not have an infinite force, in an infinitesimal time. Ultimately, Hooke's law would govern the behavior of the strings, as if they were springs with a much larger k-constant, and I would expect a sinusoidal profile of the rebound force as a function of time. The frequency would be in kilohertz or megahertz, and we'd only see a a little over half of this sine wave appear on the plot. We'd also see harmonics to this sine wave, that are governed by the natural frequency of the spring-like elements in the scale, be it actual springs or piezoelectrics, and a damping envelope as the sine wave pulse transitions back to the constant -6 gram reading..

[@carultch]

Indeed it would be interesting to see the details of this spike, but I don't know what kind of scale would have the time resolution to accurately pick it up. From the impulse-momentum theorem, you can infer that the time-average change from zero in the reading on the scale should equal zero, across a time interval between equivalent points in the cycle. No change in the momentum of the center of mass, should mean no net impulse on the system from the scale, other than the baseline impulse needed to oppose the steady impulse of gravity. The problem is, that there is such an extreme asymmetry between the time when the scale would read -6 grams, and the time of the rebound spike, that the scale doesn't have enough resolution to pick up the rebound spike, and this biases the readout to show the loss of weight, a lot more than the gain of weight. Maybe if you introduced flexible springs at the top of the strings, to slow down the rebound impulse, you could pick it up on the scale.

[@andremanicke8534]

@@carultch If you change the scale to a pressure sensor and connect it to an oscilloscope you would bei able to see it. The sensors themselves are fast enough, it's only the processing which slows it down.

[@harishwala5882]

Hello from India 🇮🇳, Congrats

[@jp-hh9xq]

Wow! I would have bet money that this effect would not occur. I guess there is always an opportunity to learn something new about basic physics. Great video!

[@PeerAdder]

This is why objects in free fall (such as those in a spaceship orbiting the earth) are described as being "weightless"). All that is happening here is that the disc is falling, but not freely, so it's weight (the force between it and the scale) doesn't go to zero. The fact that it is spinning is only relevant in the sense that it is the mechanism this setup uses to slow down the rate of falling. You could achieve the same effect by dropping a mass through a column of a viscous liquid. Use a very viscous material such a _solid_ and the mass will sit on the top of the column and the scale will read its weight as expected. Use a very non-viscous material such as a gas and the mass will fall freely so that the scale only registers its weight properly after it has come to rest at the bottom of the column. Any intermediate viscosity will produce a correspondingly intermediate reading for the weight of the object you are dropping through the column.

[@jp-hh9xq]

@@PeerAdder That makes total sense. Wasn't intuitive with this arrangement. The viscous vs non viscous liquids makes perfect sense and seems to be a good analogy.

[@MonkeySimius]

Oh... That makes sense. I kept waiting for it to peak up while it was at the bottom but it makes sense that the scale just didn't refresh fast enough to register that. I would have had thought that it would have shown a greater force while it was traveling upward... But your explanation for why that wasn't the case was really clear. Good video.

[@eypandabear7483]

This is actually a great illustration of Einstein’s equivalence principle. In general relativity, gravity is an inertial pseudo-force. That means: the disc’s weight is actually not gravity acting on its mass, but rather the force with which the scale “accelerates” the disc against its free-fall trajectory. So when the disc is allowed (partially) to fall, its weight *must* go down, because it is precisely the force which counteracts that fall.

[@JebFromWarmDays]

Love this explanation! I always enjoy thinking about how I'm actually accelerating (kind of) upwards at my weight right now haha

[@paulbrooks4395]

Does this mean it changes weight due to the change in acceleration frame of reference?

[@tomblakley105]

@@paulbrooks4395 yep

[@tomblakley105]

@@rebeuhsin6410 the scale zeros out for a fraction of a second,

[@kindlin]

@@JebFromWarmDays I do believe you're actually accelerating downwards, as gravity "pulls." Another way to think about this, is that someone in orbit is in a perpetual free fall, but you just keep missing the ground over and over again. As you stand on the ground, it does resist that falling motion, so you feel a force in your feet against the ground resisting the gravitational acceleration and keeping you as stationary relative to the slow moving tectonic plates.

[@arsilvyfish11]

This is one of the best channels when it comes to the topics that he discusses. A great plus is the amazing community that come up with engaging discussions in the comments. Glad to be a part of the Action Lab community!

[@shinronin7312]

Yeah i love it too. Its just that sometimes im like: eh? Srs someone didnt know that? Then i notice yeah not everyone is spending their free time on such shit. 💋💋❤️❤️💔💔💗💗💗💗💔💔❤️❤️💋💋

[@jimi02468]

What I always wonder about is how does he come up with the topics for his videos. But whatever the topic it's always something interesting

[@arsilvyfish11]

@@shinronin7312 lmao

[@arsilvyfish11]

@@jimi02468 yup!

[@quaztron]

Rough numbers: Its acceleration while falling down (or up) is 6g / 720g x G = 0.00833G or 0.266ft/sec². Its fall time is about 3s, so its peak velocity (just before it bounces) = at (acceleration times time) = 0.8ft/s. The distance traveled = 1/2at² = 1.2ft.

[@ahmad-murery]

Finally somebody explained those videos, Thank you and Thanks to the wife for keeping you safe to bring us these interesting videos.

[@lotsoffreetime8392]

When you discover something interesting and you share it is indeed amazing 🤩

[@bob456fk6]

This is amazing!! I thought the weight would switch back and forth between plus and minus as the wheel went up and down. Newton and Maxwell were pretty clever...this proves it. 🙂

[@열유체101]

Acceleration is not always downward. Where Wheel reaches the bottom and roll up, there is acceleration acting upward.

[@eekee6034]

This might be measured if the scale recorded the mass.

[@Observ45er]

Here's the deal with this wheel: The wheel does NOT *weigh less* when it is spinning!. .. It may be more correct to say that it weighs less when it is "bouncing". .. I have a problem with the interpretation of the Laithwaite demo. *Precession does not translate the wheel. It does not lift it.* Precession causes the axis of rotation to change direction. This is a *ROTATION* about the center-of-mass of the wheel. It is not lifting the whole wheel's mass. . Precession does not cause the gyro to *move* (translate) sideways, nor upward in Laithwaite 's case or Veritasium's case. If the vertical spinning gyro had translation, it would slide along the table, but stay vertical. It does not do that. It tips, or rotates at 90 degrees. The fact that the handle is offset and long has significance. If you push the handle in the direction of the precession, that lifts the handle, right?. However the interpretation that the spinning wheel is always accelerating downward even while moving upward, is a very good catch. It took me a few seconds to realize that. My quick initial feeling was that the weight would go positive on the way up. . . The way to think of it is that is is 'partly falling' due to gravity. When you are in free-fall you are completely 'weightless'. The spin and string-shaft arrangement allow it to fall, but not fully, as when you are in free-fall. So, the frame experiences somewhere between the full weight and weightless ness, but more weight during the bounce time. .. *The winding and unwinding of the string causes the up and down motion which is what changes the weight.* .. Stand on a bathroom scale and at a medium speed, move up and down by bending your knees. Try to move faster and faster on the way down and slower and slower on the way up. You will see your weight decrease during those times. .. .. .. If you watch carefully, you see that it is speeding-up as it drops; this is accelerating, but not at the full 'gravity-rate'. Also, it is slowing-down as it rises, again not fully accelerating (decelerating or negative acceleration) due to gravity. .. On a trampoline you are completely weightless from the time your feet leave the trampoline until they touch again and start the bounce. During this time you are constantly in 'total' free-fall. When in contact with the trampoline you are accelerating upward and weigh more than normal. If you can add a small upward force to reduce the acceleration due to gravity, you will weigh less. No surprise there. This is analogous to only "partway" jumping on a trampoline (or your bouncing ball). On a tramp, you are accelerating *downward* when your feet are not in contact with the tramp. The ball is when it is not in contact with the floor. The spinning wheel only "partly" leaves the support strings. It is "partially bouncing". If the tramp accelerated you upward at twice the rate of gravity, your weight would double. Therefore, there is also a slight increase in weight at the bottom bounce. . This would be equivalent to a small jetpack on your back that can't lift you, but only partly reduces your weight. You would be in "Sloe-Fall", not free-fall. .. This would make a wonderful Dean Drive Scam. . . . .. It would be nice to have a real-time force load cell so we can see what happens at the bottom of the wheels travel - the positive weight gain during the short 'bounce' time. .. Also, WHAT HAPPENS to the weight, if the wheel is NOT spinning, but bouncing while being suspended by a *spring,* instead of the winding/unwinding strings? Is that equivalent to this "partial bouncing" effect?

[@gentrysmith5748]

Thank you! After 55 years, I finally understand how a yoyo works. Seriously!

[@Justwantahover]

It's accellerating downwards, making it lighter. And it decellrates upwards and that also makes it lighter. Like braking makes stuff go forward inside a car.

[@SasamuelTheCool]

I've done this trick with myself, I spinner mid-air and went to see my weight, it was at NAN, worked perfectly

[@redryder3721]

Amazing demo, thanks! You showed something surprising and new yet again, I keep learning from your vids.

[@patrykzdz]

Put inside mercury, I think that's how ufo work. With mercury maybe will start antigravity proces, plus electricity to create electro magnetic field

[@stephensim5839]

Nice physics man, had me stumped.

[@VeggiePower303]

To get Anti Gravity, You need to take two high speed powered gyros on a single horizontal shaft spinning in opposite directions. And then power spin the whole thing around the vertical center line of the shaft. This creates a self intersecting Torsion field. This will allow you to climb up the Gravity well.

[@q.e.d.9112]

I thought this many years ago but I rather doubt it now. I can’t see how intersecting torsions can produce a translation, but I’m not up to date on physics. A proof of concept wouldn’t be too difficult to make and, if successful, would either get you a Nobel or, possibly, an unfortunate accident on a mountain road.😉

[@The1stDukeDroklar]

@@q.e.d.9112 🤣

[@feifeishuishui]

That won't work. You will get the same weight.

[@Markoul11]

Great video and amazing explanation!!

[@rayoflight62]

Very interesting experiment, I knew about the force vector changing but I never seen so well exposed. The cheap scale with too long sampling rate spoiled it a bit. Thanks, Anthony

[@N0_UNITY]

holy moly this channel is for big brains i can’t rap my head around half this stuff

[@paulbrooks4395]

So the force exerted at the bottom should be a fraction of the mass based on the multiplier of acceleration due to gravity. If it’s moving at half a G of acceleration, the amount of travel time gives the speed in m/s at the bottom. The speed times mass should give its instantaneous maximum force in gm/m/s-gram meters per second. I’m not sure how to calculate the fractional weight loss during the rest of its motion period. I think it’s the instantaneous maximum force divided by the travel time. That should give us a constant in gm or possibly gram/meters?

[@jcmschott1895]

Hey, mate! I did it taking into account the rotational and linear equations of motion. The weight loss read in the scale is a function of the square of the quotient between the rod radius and the disc radius, if I am not mistaken. You may think of the difference in the scale reading as twice the difference in the tension in the strings and there will be some difference as the disc is put in movement.

[@zulfakaraspar2311]

At 1.45s, it is wrong to reset or zero out the weighting machine. You should hold the wheel so that it does not put pressure or weight on to the weighing machine. Then you reset the weighing machine. After releasing the wheel, the reading will be only the wheel's weight. When the wheel spins, whatever changes to the weight machine reading will be shown either positive or negative readings. In addition, since the changes are quite fast for human eyes, you should use a data logger to record the measurement. Then, you should analyze on a computer during the maximum and minimum height of the wheel. Anyway, it is a good experiment. Keep up the good work.

[@prabhakaran1981]

You may have a scale for each string and then measure the mass. Each scale may show different value due to the gyroscopic effect. When this wheel rotates in a direction one sting may have less tension and the another one may have tension equal to half (or zero) of the (wheel) mass. But due the change in direction for each cycle, string alters.

[@dilipdas5777]

Great. I think it's correct explanation

[@Observ45er]

Nope. Both strings will show the same as long as the horizontal distances from string to center-of-mass are equal. .. Here's the deal with this wheel: The wheel does NOT *weigh less* when it is spinning!. .. It may be more correct to say that it weighs less when it is "bouncing". .. I have a problem with the interpretation of the Laithwaite demo. *Precession does not translate the wheel. It does not lift it.* Precession causes the axis of rotation to change direction. This is a *ROTATION* about the center-of-mass of the wheel. It is not lifting the whole wheel's mass. . Precession does not cause the gyro to *move* (translate) sideways, nor upward in Laithwaite 's case or Veritasium's case. If the vertical spinning gyro had translation, it would slide along the table, but stay vertical. It does not do that. It tips, or rotates at 90 degrees. The fact that the handle is offset and long has significance. If you push the handle in the direction of the precession, that lifts the handle, right?. However the interpretation that the spinning wheel is always accelerating downward even while moving upward, is a very good catch. It took me a few seconds to realize that. My quick initial feeling was that the weight would go positive on the way up. . . The way to think of it is that is is 'partly falling' due to gravity. When you are in free-fall you are completely 'weightless'. The spin and string-shaft arrangement allow it to fall, but not fully, as when you are in free-fall. So, the frame experiences somewhere between the full weight and weightless ness, but more weight during the bounce time. .. *The winding and unwinding of the string causes the up and down motion which is what changes the weight.* .. Stand on a bathroom scale and at a medium speed, move up and down by bending your knees. Try to move faster and faster on the way down and slower and slower on the way up. You will see your weight decrease during those times. .. .. .. If you watch carefully, you see that it is speeding-up as it drops; this is accelerating, but not at the full 'gravity-rate'. Also, it is slowing-down as it rises, again not fully accelerating (decelerating or negative acceleration) due to gravity. .. On a trampoline you are completely weightless from the time your feet leave the trampoline until they touch again and start the bounce. During this time you are constantly in 'total' free-fall. When in contact with the trampoline you are accelerating upward and weigh more than normal. If you can add a small upward force to reduce the acceleration due to gravity, you will weigh less. No surprise there. This is analogous to only "partway" jumping on a trampoline (or your bouncing ball). On a tramp, you are accelerating *downward* when your feet are not in contact with the tramp. The ball is when it is not in contact with the floor. The spinning wheel only "partly" leaves the support strings. It is "partially bouncing". If the tramp accelerated you upward at twice the rate of gravity, your weight would double. Therefore, there is also a slight increase in weight at the bottom bounce. . This would be equivalent to a small jetpack on your back that can't lift you, but only partly reduces your weight. You would be in "Sloe-Fall", not free-fall. .. This would make a wonderful Dean Drive Scam. . . . .. It would be nice to have a real-time force load cell so we can see what happens at the bottom of the wheels travel - the positive weight gain during the short 'bounce' time. .. Also, WHAT HAPPENS to the weight, if the wheel is NOT spinning, but bouncing while being suspended by a *spring,* instead of the winding/unwinding strings? Is that equivalent to this "partial bouncing" effect?

[@Observ45er]

@@dilipdas5777 Here's the deal with this wheel: The wheel does NOT *weigh less* when it is spinning!. .. It may be more correct to say that it weighs less when it is "bouncing". .. I have a problem with the interpretation of the Laithwaite demo. *Precession does not translate the wheel. It does not lift it.* Precession causes the axis of rotation to change direction. This is a *ROTATION* about the center-of-mass of the wheel. It is not lifting the whole wheel's mass. . Precession does not cause the gyro to *move* (translate) sideways, nor upward in Laithwaite 's case or Veritasium's case. If the vertical spinning gyro had translation, it would slide along the table, but stay vertical. It does not do that. It tips, or rotates at 90 degrees. The fact that the handle is offset and long has significance. If you push the handle in the direction of the precession, that lifts the handle, right?. However the interpretation that the spinning wheel is always accelerating downward even while moving upward, is a very good catch. It took me a few seconds to realize that. My quick initial feeling was that the weight would go positive on the way up. . . The way to think of it is that is is 'partly falling' due to gravity. When you are in free-fall you are completely 'weightless'. The spin and string-shaft arrangement allow it to fall, but not fully, as when you are in free-fall. So, the frame experiences somewhere between the full weight and weightless ness, but more weight during the bounce time. .. *The winding and unwinding of the string causes the up and down motion which is what changes the weight.* .. Stand on a bathroom scale and at a medium speed, move up and down by bending your knees. Try to move faster and faster on the way down and slower and slower on the way up. You will see your weight decrease during those times. .. .. .. If you watch carefully, you see that it is speeding-up as it drops; this is accelerating, but not at the full 'gravity-rate'. Also, it is slowing-down as it rises, again not fully accelerating (decelerating or negative acceleration) due to gravity. .. On a trampoline you are completely weightless from the time your feet leave the trampoline until they touch again and start the bounce. During this time you are constantly in 'total' free-fall. When in contact with the trampoline you are accelerating upward and weigh more than normal. If you can add a small upward force to reduce the acceleration due to gravity, you will weigh less. No surprise there. This is analogous to only "partway" jumping on a trampoline (or your bouncing ball). On a tramp, you are accelerating *downward* when your feet are not in contact with the tramp. The ball is when it is not in contact with the floor. The spinning wheel only "partly" leaves the support strings. It is "partially bouncing". If the tramp accelerated you upward at twice the rate of gravity, your weight would double. Therefore, there is also a slight increase in weight at the bottom bounce. . This would be equivalent to a small jetpack on your back that can't lift you, but only partly reduces your weight. You would be in "Sloe-Fall", not free-fall. .. This would make a wonderful Dean Drive Scam. . . . .. It would be nice to have a real-time force load cell so we can see what happens at the bottom of the wheels travel - the positive weight gain during the short 'bounce' time. .. Also, WHAT HAPPENS to the weight, if the wheel is NOT spinning, but bouncing while being suspended by a *spring,* instead of the winding/unwinding strings? Is that equivalent to this "partial bouncing" effect?

[@itonyg976]

Man, your channel , your videos, your explanation are Fword AMAZING, please keep it up.

[@colorado841]

That explains a lot. I always wondered how fly saucers worked!

[@arjunravi1641]

How?

[@carultch]

This has nothing to do with how flying saucers work. Flying saucers are all just a big speculation of what an alien spacecraft might look like.

[@johnniefujita]

one of the most interesting videos about classical gravity

[@DANGJOS]

The only thing confusing to me was why the weight didn't increase upon hitting the bottom. I guess the refresh rate was the only reason.

[@jesucristojesus3676]

this is very easy to understand. I have known about this for years, and the reason why it goes -w its because of the effect on the string.

[@colorado841]

I wonder if this method could be exploited to move heavy objects across distances with minimal friction do to gravity.

[@brads9418]

Maybe that’s how the Egyptians built the pyramids!

[@johnnycash4034]

@@brads9418 nooooo! Yes! Yes that's it! OMG!

[@loganthesaint]

@@johnnycash4034 more likely they used vibrations of some sort.

[@johnnycash4034]

@@loganthesaint nooooo! Yes! Yes absolutely! That's it!

[@DamianReloaded]

I was thinking about a crane that used this, but the wheel in this video must weight at least 500g (probably more) and it only loses 6g for a relatively short period and you have to use energy to roll it up. The cases where you'd need to move something that is 1% too heavy are probably no worth the complexity of such a crane.

[@politicalfoolishness7491]

I love this video and I know more than the average person about physics.

[@Cretan1000]

If you plotted it at a high refresh rate, and looked at the area under the curve of the measured weight, would it average out to zero (slight negative most of the time, very positive for a fraction of a second as it bounces up)?

[@megamaser]

Yes, actually it would be slightly positive because energy has mass. But it would be very close to zero

[@my3dviews]

@@megamaser No. Energy does not have mass. Light is energy and massless. Mass can be converted to energy such as in a nuclear reaction, but that does not mean that energy has mass. In the experiment in the video, the mass never changes. What changes is the downward force on the scale due to the change in rotational speed of the wheel. The overall downward force over time is equal to the weight of the wheel. So, while it is changing speed the downward force is less, but at the point where it comes to the end of the strings, there would be a surge to equal out the loss over the rest of the time. This would be similar to dropping an object on a bungee cord. When it is falling the force on the connection point would be lower than the weight of the falling object. When it hits the bottom there would be a surge, then it would be lower again on the way up. The overall weight times time would be the same as the weight of the object at rest over an equal amount of time.

[@megamaser]

@@my3dviews Einstein showed that mass and energy are equivalent. Mass is basically a confined form of energy. So yes a free photon has no mass. But if you trap a photon in a box of mirrors then it will add mass to that box. The mass of protons and neutrons primarily comes from the kinetic energy of the quarks, which are confined by the strong force. Adding energy to an object by heating, vibrating, or rotating that object increases its mass.

[@my3dviews]

@@megamaser Quote: "Einstein showed that mass and energy are equivalent." Wrong. E (energy) = m (mass) x c(speed of light) squared. Notice Einstein's equation is not simply E=m. Getting back to your first claim that energy has mass. That is incorrect. Mass can be converted to energy and energy can be converted to mass, but energy itself does not have mass. Your last comment even admits that. It says that a photon trapped in a box of mirrors will add mass. That is converting energy into mass, since the photon no longer exists. That is not the same as saying "energy has mass". (it doesn't).

[@megamaser]

@@my3dviews Interesting how you're so sure of yourself but obviously not doing any actual research before making these assertions. I'm only stating some indisputed scientific facts that were established 100 years ago. Anyone with even only a bs in physics should know these things. I'll address your points one by one, but you seem pretty hostile to new ways of thinking, so I'm doubtful that it will be very fruitful. Anyway... "Einstein's equation is not simply E=m" Actually, it is, essentially. c is only a constant. It's an arbitrary scaling factor that's only used due to the choice of units. He included it mainly to illustrate the insanely large amount of energy in small amounts of mass. But it can be left out without impacting the equivalence. If you choose some other units, then you don't need the scaling factor. It's actually quite common to use energy units to measure mass, such as electron volts. Trapping the photon in a box of mirrors does not destroy the photon. It continues to exist, reflecting against the mirrors. If you open the box, the photon will escape. It's a commonly used thought experiment to illustrate mass energy equivalence. There are some nice KZbin videos to visualize this example. Converting mass to energy means you have released confined energy. Converting energy to mass means you have confined energy. For example, endothermic chemical reactions consume energy to bring electrons into a higher energy level. Usually this is thought of as a conversion from kinetic to potential energy. But that potential energy has mass, we know this because endothermic reactions result in products that have greater rest mass than the reactants, so it can also be considered to be a conversion of energy into mass. But if you consider the heat that was absorbed, it was also contributing mass to whatever was hot, so the overall mass of the entire system is unchanged. The energy was always massive, and the mass was always energy. Likewise, exothermic reactions, like fire, can be said to convert mass into energy, because the reactants have greater rest mass than the products. However this lost mass was manifested in the potential energy of electrons, and it actually isn't lost since the thermal energy still contributes mass to the entire system. It is a little weird to say that energy "has" mass. I think it's more accurate to say that mass *is* energy. Mass is an emergent phenomenon that results from the confinement of energy.

[@sceptic2061]

I was like, what about the digital frequency to show the measurement, and you delivered! TY!

[@frogandspanner]

I remember watching this effect in 1974 in _"The Jabberwock" Eric Laithwaite 1974 RI Christmas Lectures, Lecture 4_ . We looked at this in Physics tutorials during my degree. It's an example of conservation of angular momentum. The angular momentum of the rotating wheel is changing owing to the rotation of the Earth.

[@rogerphelps9939]

Nothing to do with the rotation of the Earth.

[@frogandspanner]

@@rogerphelps9939 Kindly explain.

[@ChevronDiscount]

Very cool! Always love your videos!

[@XploringMyself]

This concept is similar to hydraulic shock absorbers but in this case its "Gravitational Shock Absorber"

[@clahey]

No, it's a rotational shock absorber

[@EskWIRED]

This is all very simple. But it is also very mind-bending. Thanks.

[@revealingfacts4all]

Looks to me a couple things are going on here. 1. Scale update rate is slow compare to actual 2. There is always a counter acting upward force from the converted potential energy which causes the wheel to climb back up the rope. You'd see the same effect with a spring. The stored potential, as it decreases, is always countering the downward force the scale is measuring. In a way, your scale is showing force changes as they occur (well, at a refresh rate the scale is keeping up with).

[@brads9418]

I wonder if the same antigravity effect happens with just a spring.

[@feifeishuishui]

Intriguing! At the beginning, I was lost, but then I realized it was kind of like when I was jumping on the scale. Most of the time, I would weight zero, but when I was physically touching the scale, my weight goes up a lot.

[@OGbqze]

I wonder if weight lifting competitions have rules against spinning weights being used?

[@modernviewscience6745]

Eric Laithwaite (Dec 74 lectures on youtube) did brilliant demonstrations for sure. Without spin at 2,500 rpm or more, you cannot lift that weight, especially since it's located a foot and a half away from your hand. So this effect is classically explained by the math of objects in rotation with angular momentum and torque. BUT looking a bit outside that "box" the question is about action-reaction (3rd Newton's law); What is this "torque" pushing against? Without something to react against, you just cannot have torque, and without it, you cannot explain why it's so easy to lift. I toyed with this (you need a decent mass and speed to perceive it), and when your body becomes the axis of rotation, hold it in one hand moving it around in one direction (clock wise or counter clock wise, depending on how your gyro is spinning) then it will "want" to lift. And (amazingly) when your body tries this in the opposite direction, the thing becomes nearly impossible to hold as it "wants" to dive downward! Try this with a decent (heavy and large) gyro. No, it's not a gravitational effect for sure, otherwise gyros would not work in deep space. But if you care to look very carefully into it, and find similar studies (practical studies; try to stay clear of arm-chair or purely mathematical interpretations) then you may conclude that it affects the inertial properties of that object. Some believe that inertia is an intrinsic property of mass, whereas you'd be at a loss trying to find one aspect of physics that isn't affected by or affecting something else. Angular momentum does influence inertial properties. Again, rotating it in one direction makes it easy to move 10kg on a lever, upward (while circling it in a corkscrew motion), while the opposite makes it very difficult - I promise you will need to wrestle with both arms to keep it from sinking down! all the while you stand of a scale that won't budge. Spinning a Fidget and trying to move it this way and that way, will do the same but weakly. Your show is one of the very best and most exiting science show-and-tell that exists in the world. We are very grateful for all that you do! May the day, when the muse of Science has revealed all her secrets, never come for we will die of boredom. 🚀😀

[@zaphodbeeblebrox2817]

I remember a theory of how ufo's work where the ship has a big toroid of mercury. The mercury would flow axially and radially through a section of the toroid. The radial flow in a section is actually axial flow around the whole toroid. So if you could magically move/spin/swirl the mercury, you could control its gravity

[@vaakdemandante8772]

It either makes no sense or I don't understand what you've wrote. Please rephrase that in terms of a picture / sketch, so I can grasp exactly what you mean by axial / radial flow.

[@zaphodbeeblebrox2817]

@@vaakdemandante8772 a liquid flywheel that can spin on two axes simultaneously

[@tristanbrandt3886]

I wonder if quarks, electrons, create gravity with their spin? Get enough of a mass together, and the spin of all those atoms creates a higher density, and therefore higher gravitational force.

[@reagindoerindo4311]

But the flywheel acceleration keeps still. How could the ship zero an external body gravitational acceleration? The flywheel went upward because the downward acceleration winded a wire to roll up. How could a ship ignore a planet gravity and just fly upwards effortlessly, not being winded to anything? ... This is one of those unintuitive talks, like quantum physics/mechanics. I like it, it makes the brain works.

[@uriahgibson9022]

@@tristanbrandt3886 or does the gravity create the quarks and electrons? If there is gravity everywhere there is a quark or electron, what if gravity created them to balance itself or something to that effect. Does the electron or gravity come first or at the same time?

[@grazianoturbogas]

That's huge! It will keep me intriguing for months

[@howiestillgamez5326]

Would the same effect be measured from a pendulum swinging back and forth?

[@NetAndyCz]

Maybe, but it would be minor because the pendulum lowers its center of mass only my rather small distance. But I think the same principle would work for weight-driven clocks as well.

[@carultch]

When the pendulum bob accelerates upward, there is an apparent gain in weight. When the pendulum bob accelerates downward, there is an apparent loss in weight. The centripetal acceleration is from the rod pulling the bob inward, and the tangential acceleration is from the component of gravity that makes it swing. We can calculate when this will happen by finding the net y-component acceleration, and determining the critical angle where it is zero. Given an amplitude angle of A, I derived the following formula for the critical angle theta_crit, where the vertical acceleration switches direction. theta_crit = 2*(arctan(sqrt((2 - sqrt(cos^2(A) + 3))/(cos(A) + 1)))) For small amplitudes, this approaches sqrt(2)/2, or 70.7% of the amplitude angle. For a 30 degree amplitude, it's 69%, or at 20.9 degrees. The critical angle becomes a smaller fraction of the amplitude, the higher the amplitude. The extreme case of a 180 degree amplitude has a divide by zero problem, but we can calculate it for angles arbitrary close to 180 degrees and get that it happens at around 39% of the amplitude. Also for small amplitudes, where you can approximate the pendulum as simple harmonic motion, this occurs at the half way point in time between its release point at the amplitude, and the neutral point where it passes through the middle. This means that it spends half its time weighing less than it does at rest, and half its time weighing more than it does at rest, when weight refers to the vertical component of the scale's support force. a 30 degree amplitude, it's 69%, or at 20.9 degrees. The critical angle becomes a smaller fraction of the amplitude, the higher the amplitude.

[@axle.australian.patriot]

You could exemplify this same effect with an old pendulum clock. Not due to the pendulum but the weights that powered the clock. The weights on strings would have a constant acceleration toward earth until such time as the string completely unwound, then it would resume is natural still weight.

[@carultch]

@@axle.australian.patriot You'd get that if you took out the escapement mechanism, and put the hanging weights on ideal pulleys, like Atwood's machine.

[@axle.australian.patriot]

@@carultch No, just an old pendulum clock (With wind up weights) will produce exactly the same effect :)

[@marklefler4007]

Thanks! Keep up the great videos educating people about science in a fun way.

[@peterwhitey4992]

The rotation has nothing to do with the experiment. You could as well have hung it on a spring. It's similar to standing on a scale and throwing on object into the air. While it's in the air, the scale shows less weight than when you're holding it.

[@VeteranVandal]

Or jumping on a scale.

[@sequoiahughes8536]

Well put-that’s a great explanation

[@mbrusyda9437]

It does, actually, it introduces the asymmetry between the upward and downward accelerations. Springs don't have that property.

[@nenhard]

So called weight loss yo-yo effect

[@honestopinion6268]

Thanks for finally explaining the Great Pyramids

[@OriginalMorningStar]

I wonder if this effect contributes to the Chain Fountain physics. Seeing as the chain is technically spinning as it form the loop, and weighs less at that point as a result, this could be the dominant force?

[@AdrianBoyko]

This is a really interesting question! I don’t think that “spinning” figures into the weight reduction (its just an energy storage mechanism) but the chain in a chain fountain is definitely accelerating downward as it changes direction from flying up to flying down. And, surprise, surprise, it’s the decelerating portion of the chain that rises! I think you may have discovered the REAL reason for chain fountains!

[@u1zha]

But chain fountain weighs more, not less, while in operation. Steve Mould had series of videos about the kickback

[@TheBradfordG]

"undisclosed safety incidents". Comedy gold--thanks for teaching us something along the way!

[@amitkriit]

At zero, the scale accounts for the tension in the string which is less when the wheel starts to spin, reducing the normal force acting downward at the scale.

[@chrstfer2452]

You did a good job explaining on this one. Keep it up.

[@OmegaZZ111]

Interesting effect, well shown, thank you! Would be interesting to know what the phenomenon of gravity really is and how everything is really tied together.

[@peterwhitey4992]

It's just bouncing on the scale. If you bounce a ball on a scale, while it's in the air, the scale shows less weight. The rotation of the disc has nothing to do with it. He could as well have used an object on a spring.

[@OmegaZZ111]

@@peterwhitey4992 I don't think that's the same. The scale shows a continuous negative weight, you wont get that from bouncing a ball on a scale.

[@peterwhitey4992]

@@OmegaZZ111 - It is the same. The scale just doesn't update fast enough, to show the force of the bounce.

[@OmegaZZ111]

@@peterwhitey4992 The rotating mass and the precession along another axis creates a measurable loss in weight. This effect is clearly shown in the video with the rotating flywheel with a handle that is easy to lift when the mass is rotating. This is not the same effect as a ball bouncing on a scale. It is not about the scales refresh rate, the rotating wheel is actually loosing weight. While the mass of an object is constant the weight is dependent on many factors.

[@carultch]

@@OmegaZZ111 The rotating and precessing mass doesn't create a loss in weight. It is more like a loss in torque that makes it easier to lift, than a loss in weight. If you weigh yourself while lifting that wheel, you will see no weight loss while the wheel rises at a constant speed. Only a weight loss when you slow it down at the top. You will also see a weight gain at the bottom when you initially lift it. The rotating wheel makes it easier to lift, because you only need to lift against its weight, and don't need to lift against the torque due to its weight. You only lose weight in a system in motion, when the center of mass of the system being weighed accelerates downward. Or if you go to another location where the value of g is less.

[@josem138]

Ey I do use Notion, notion is great. Thanks for showing it, because is very interesting to organize

[@TVCHLORD]

congratulations you discovered a yo-yo

[@IzySly-g4h]

You are you tubes answer to the question that no one asked.

[@adventure9544]

😂😂😂😂

[@Very.Crazy.Math.Pistols]

And it is well explained if it is replaced with a mass spring. The mass accelerating less than mg, weights less all the time until potential energy is gone by friction ( because weight = mg ), so that parte of the instrument weights less.

[@kanpurunplugged9970]

actually it's the freely suspended slinky spring drop experiment in disguise

[@darrenoak7187]

This is an excellent demonstration, thank you .

[@CorvanEssen]

You've probably also dropped a magnet to a copper or aluminum pipe. The magnet drops really slow due to current in the non magnetic metal. But what would a scale say under the pipe?

[@VeteranVandal]

Pipe+magnet mass, basically. Wait... That's actually a way to measure mass while it moves... That might be useful for some application.

[@johnschewe6358]

Whatever percentage of force the magnetic field opposes gravity should be seen in scale at the bottom as something has to be equal and opposite to the force of gravity to slow down it's fall.

[@VeteranVandal]

@@johnschewe6358 all of the force opposes it for a long enough pipe, when the falling speed gets constant.

[@johnschewe6358]

@@VeteranVandal Much like how you only feel weightless on an elevator while it's speeding up.

[@woodennecktie]

using that painfully slow scales demonstrates the flaw in the setup . use some real faster balancing dynamic scales and the setup even deliveres so much more results aswell as pricipels you actually can use

[@ValentinStavrevZmey]

The tricky part is when the wheel changes its movement from falling to climbing - the sudden short kick can be registered by electronic balance, so antigravity discovery is postponed.

[@Spedley_2142]

it would be interesting to see the whole rig on one side of a balancing scale. You'd be able to see the whole thing rise slightly but the jolt at the bottom should put it back to the origjnal position.

[@ckEagle165]

I'm curious about something in a perfect vacuum, all other variables such as gravity, elevation, etc being equal. If you have an item like this creating friction, in air the heat from that friction, plus the sound, has air to travel through. In a vacuum, there's no air to take heat away from the heated friction elements. So technically, shouldn't friction cause the items to slow down faster? I hope my question made sense.

[@areadenial2343]

No, friction only converts energy to heat, and it doesn't get "more powerful" as temperature increases. If heat isn't allowed to escape, then the mechanism will just keep accumulating heat until it begins to break down. But you may be surprised to learn that heat does escape in a vacuum! All objects steadily lose their heat as electromagnetic radiation, mostly in the far infrared. This can account for around 30% of heat transfer even in a normal atmosphere. So putting this wheel device in a vacuum won't cause it to lose energy faster, but it might be 0.1 of a degree warmer since that heat will dissipate more slowly.

[@stevewhitt9109]

Great Video. Best explanation on KZbin.

[@Extrify_]

Tomorrow is my math exam But I'm more interested in your channel ʘ‿ʘ

[@barry7608]

Thanks always learn something from your vids and you’ve never hoaxed on any. Awesome

[@ianmlclm7044]

Interesting! Can you conduct a more precise experiment with no falling parts? With an aluminium disc rigidly fixed, rotating with no up-down forces, except mg, the period of rotation of the aluminium disc being 1/2 of the time it takes time for aluminium to change polarity and very precise scales? My prediction is that with the conditions mentioned, the Al disc will lose the % of weight equal to the % of Al magnetic features opposed to the "perfect magnet" with no non-magnetic alloys (non-existent). I'm too poor to conduct this kind of experiment, unfortunately. Thank you!

[@morganp7238]

This

[@G_Mustafa]

Hey, can u do this practical 👇 Do condrinks get colder when it pressure releases, bcoz when pressure will realese gases ( or co2) will take heat from surrounding In result it should cold the drink (maybe a little bit but can u try it out) Oh i have title for you "do coldrings cold itself"

[@id104335409]

Time to make a box that holds the disk and spins it up really fast. So fast that it lifts it to the negative value of its own weight. And break the internet.

[@MrT------5743]

It isn't the spinning that cause a decrease in weight though. It is the falling that decreases the weight.

[@carultch]

Take it on a roller coaster and perform this experiment at the top of an inverted loop. Then it will appear to lift itself from your point of view.

[@MrT------5743]

@@carultch it already appears to lift itself when it is going up from the momentum of the spin.

[@carultch]

@@MrT------5743 It isn't really lifting itself. It's just that the center of mass is accelerating downward, so it doesn't need as much support to keep it from sinking through the floor. But no matter what you do in this setup in a stationary environment on this planet, its acceleration will be less than g, and it will still compress the scale. You would have to have its center of mass accelerate downward at a rate greater than g, for it to lose contact with the pan of the scale. One way you could achieve this, is if you spun a heavy ball on a string so fast, tied to the top of that frame, that the tension in the string at the top of its motion exceeded the weight of the stationary framing. You better adhere it to the scale and fasten the scale to the floor, if you don't want it to fly away.

[@kevinmorgan2317]

The weight registered on the scales will be the total weight of the support frame plus the tension (converted to grams) in the two strings. While it's unwinding on the fall phase, I can see why the tension will be less than in the stationary hanging mode. But why the tension would be still be less in the climbing phase puzzles me. I'm not sure that's been explained. Great videos.

[@kevinmorgan2317]

Actually, it would be interesting to see if the tensions in each string were the same... (strain gauge?). I suspect there could be a difference where one string is largely supporting and the other largely preventing precession. Do they switch on the way up? Or does the one preventing precession switch to preventing precession in the opposite direction?

[@RIMESSSSSSSSSSSSSSSS]

Right? Everyone in here is pretending it makes perfect sense when it makes absolutely no fucking sense at all.

[@petehiggins33]

He did explain it in the video. After the wheel bounces at the bottom of it fall, it's moving upwards at its maximum speed. As it rises is gets slower and slower until it stops at the top. So it's upward acceleration is negative and this is the same as saying that its downward acceleration is positive just the same as when it's falling.

[@adb012]

Just starting to watch this video, I am at 3:00: "So when I first saw this I was really confused". Where you, really? I can't believe you. This is very interesting, but also very obvious for someone with a basic understanding of Physics (and you have more than basic). I knew that the scale was going to show less when the wheel is on its way down and on its way up. On both occasions the wheel is accelerating down so the weight(*) has to be greater than the tensions, and because the weight doesn't change, it is the tension the one that has to diminish, so the string is pulling down nor as hard on the frame, and the frame is not pushing as hard on the scale. TO see it in another way, since the wheel is accelerating down and the frame is not moving, the center of mass of the wheel - frame system is accelerating down, and hence the normal that the scale puts on the system has to be lower than the weight of the system. It is exactly the same reason why the scale shows less when you are on it and crouch down (during the down-acceleration phase). The only "mystery" here is why the scale doesn't show more (and A LOT more) when the wheel bounces back at the bottom. The average acceleration on a whole cycle is zero (the wheel doesn't go anywhere and ends up in the same spot where it started), so all the cumulative downwards acceleration that the wheel experiences while speeding up on its way down and slowing down on its way up is compensated by a very brief but very intense upwards acceleration when it bounces back at the bottom (what is known as an "impact"). So why doesn't the scale register that? My hunch is simply that the scale simply doesn't have a quick enough response time, so that brisk huge but very brief upwards force is jut not captured by the scale. (*) With "weight" I mean the force due to gravity, m*g, not the other thing sometimes called weight which is what the scale registers, which is the reaction to the normal force that the scale puts on the object on top) EDIT: 5:40, so here it comes.

[@jamesdavis3851]

It's a little counter-intuitive that the scale doesn't register higher while the mass moves upward. I've taught physics for 15 years, and a normal intuition is that something is pulling it up while it's rising. I've seen far better physicists scratch their heads for a few moments over similar things. "Really confused" might be an exaggeration, but there's no shame in admitting that simple stuff can trip you up. (see veritasium's bullet block experiment for a favorite example!)

[@adb012]

@@jamesdavis3851 ... No shame at all. Just that I don't believe that he was confused.

[@toolguyslayer1]

1:01 we call that a yo-yo 😆

[@Bigman74066]

If you had a perfect scale that would average the measured weight over a period of say, 10s it would indicate 0g again.

[@aetius31]

I dont think so, the weight oscillate between -5 and -8 during a long time compared to the full weight spike. In fact it will depend on the refresh rate of the scale and for a perfect balance with infine resfresh rate the contribution of the full weight spike would be tiny because the negative moving phase last much longer.

[@MrT------5743]

Even if you could average the weight out from releasing it at the top till it stops at the bottom it wouldn't be 0. Because it lost some of its potential energy. For the time it is falling, it weighs less.

[@TheActionLab]

Nope, it never goes into the positive the whole time it is bouncing up and down. This is longer than 1 minutes of bounce time. It is definitely a weight decrease, not some scale averaging effect.

[@peterwhitey4992]

@@TheActionLab - It does go positive during the bounce, but as you said, the refresh rate of the scale isn't fast enough to show that. It weighs less while going up and down, but weighs more during the bounce. The average over enough time it is of course zero.

[@aetius31]

@@peterwhitey4992 Nope I explained earlier why and The action lab confirmed it, also keep in mind that it is only true while the wheel is spinning of course

[@moodberry]

To add to what you said about a bouncing ball, the "negative" weight of the ball during freefall is suddenly transferred when the ball hits the ground. So there is no freeing of energy. It is simply converted from potential energy to actual mass (energy) and can be measured.

[@charminglily8496]

When you are early and don't know what to say😅

[@kg4boj]

0rd!

[@kg4boj]

@@happy_pikmin5540 y'ou'are

[@wrsdes]

Just an observation, due to the force exerted on the twines, there is a weight applied on the contraption registering a weight irrespective of the direction of movement of the disc. This difference is the observed weight on the scale.

[@clintnorton4322]

Use an analog scale for real time readings. The system is temporarily "throwing off" mass as the wheel descends. There is then a momentum induced spike in "weight" when the wheel hits bottom. As the wheel ascends the system will have a higher weight than when at rest. The limitation is in the response time of the scale, leading to an anomalous conclusion.

[@bingbong3221]

"Your results don't match up with my preconceived conclusion so obviously your experiment is wrong."

[@clintnorton4322]

@@bingbong3221 My high school physics teacher did this experiment, with an analog scale because digital didn't exist at the time, to demonstrate several physical principles, including the difference between potential and kinetic energy, intertia and momentum, and a couple of others. The weight at the top of the winding has potential energy as stated in the video. When released it released as kinetic energy. As the weight moves toward the bottom of the system it retains its full mass but it registers a lower weight because the mass is in motion toward the measuring device, a gravitational doppler effect. When the weight reaches the lowest point of travel momentum causes an artificial gain in measured weight by overcoming the inertia of the system and pulling the system harder into the measuring device. As the weight moves upward the system will have a higher measured weight than at rest because of the movement of the weight away from the gravitational pull, an inverse gravitational doppler effect. The digital scale he used isn't designed to show that kind of fluctuation in measurement. Run the experiment with an analog scale and you'll find the above results. The system used by my physics teacher was taller with a larger weight that allowed the use of a lower sensitivity scale.

[@bingbong3221]

"That digital scale I know nothing about from a technical perspective is obviously wrong because I remember my high school teacher getting different results 30 years ago. Just trust me!"

[@r2dxhate]

You should try holding a large hand router. The gyroscopic forces inside are crazy. You could probably put it on the end of a pole to recreate the spinning disc experiment.

[@opaque2208]

Wonder what this experiment would be like in a vacuum. I'd assume it would stay in place, unless the string has potential energy. FTL would require a loss in mass but we can't loose mass we have to find a way to disperse it or invert it's affects............aaand, I lost myself.

[@johnnycash4034]

The string has friction

[@kyhonjan]

This is a really simple system but unexpectedly difficult to realise what it truly going on. Throughout the video l was like "IMPOSSIBLE... IMPOSSIBLE" A brilliant discovery and revelation. I always enjoy your masterful yet simple videos.

[@rxotmfrxotmf8208]

Thanks for another thought-provoking video.

[@MrVibrating]

Decreasing the moment of inertia of the weight (the radius of the rotating mass from its axis), while keeping the absolute amount of weight, and the spool radius, constant, will likewise reduce the net gravitating weight. Conversely, increasing the MoI while keeping all else equal will decrease the effective weight variation..