Cavendish Postponed
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- Опубликовано: 16 окт 2024
- It's been a while since my last video! Part of this was trying to get this design to work (spoiler alert: I wasn't able to), part was because the school year started and I got back to my normal, busy teacher routine, and part was because I felt like I had failed in this and wasn't especially anxious to post that.
Ultimately, I think the problem boils down to materials. To get better results, I should have used rigid walls. Rigid walls that you can see through are going to add expense, rigid walls that you can't see through make for a crummy video.
Also, a denser material for the weights would have worked better. Planning ahead for materials, I calculated how sensitive the device would need to be in order to get a noticeable shift when I put the weights nearby. Because the weights are not made of especially dense materials, the center-to-center distance between the masses was larger than I'd have liked, meaning the gravitational forces were smaller and the device needed to be more sensitive. Making the device more sensitive means that any little air currents are going to cause more noticeable errors as well (which made the whole thing unusable).
I recognize that part of conducting a science experiment is not claiming conclusive results unless you have reason to be highly confident in the experimental data. That being said, it sucked to work on this for so long and not get anything I could use from the experiment.
I'll be working on some smaller-scale videos in the near future; things I know I can get to work the way I want them to. If you've been with me for a while on this project: thanks for coming along. I have ideas for the next version of this project, but I'm not sure when exactly that will be.
Royalty-free background music from www.bensound.com/ .
A hello from Brazil, I hope you can continue with the experiment soon.
Just came across this and subscribed, thanks for trying. I will tell others about your channel.
Subscribed to this channel based on this video - wishing you all success with your future plans!
Man, that’s a bummer. But keep making videos! I just found your channel and I think you’ve got big potential.
Darn, was hoping this had moved along. Will look forward to the next time you update!
Henry Cavendish did this in an enclosed shed. Make all your stuff remote controllable using wireless / ir so that you don't have to go in
lynx yellow strings and pulleys should work
Hi its been great watching the progression of the attempts to repeat the experiment. With troubles of isolating the torsion balance from outside influences would it be better to enclose the torsion bar within a much smaller, narrow enclosure. Shaped to fit the T shape of the bar and string. This would limit the air space around the torsion bar which would limit any air currents inside the box. The box could be made very narrow since the deflection you are expecting to measure would only a few degrees. The larger weights could then be moved by you by hand without disturbing the balance. Sorry if you have already tried this.
I think what you have made there is a super sensitive Earth magnetic field detector. The Earth's magnetic field wobbles all over the place, so using iron weights is surely asking for trouble?
1. That plastic sheet builds up a lot of electric charge that spoils everything. DO NOT use plastic parts, they build up electric charges from air currents...
2. Use nonmagnetic materials for weight
3. scale down that rod and your torsion balance, use smaller weigts, then use as thin torsion wire as possible, because the torsion constant is proportional to the 4th power of wire diameter. So you gonna have larger deflection angles on a smaller torsion balance.
highly electrostatic setup. Hair raising? Thanks for the honesty and efforts.
Hope you get back to it!
I've been using these videos to try and replicate some sort of Cavendish . We've now moved into using some code to fourier transform the signal so that we can eliminate the air currents/random deviations. Maybe this is something worth looking at?
It's an interesting idea, for sure! I do think there's conflict between the goals of making this experiment as precise and reliable as possible, and of making this experiment interesting and accessible on RUclips. I'd be interested to see your results!
Thanks for your effort buddy ... finding very few legit Cavendish experiments filmed and posted online... also if you wouldn't mind using nothing metal that would also be great . Many metals that are considered non magnetic actually have weak magnetic properties that may be strong than the less than 1% weak gravity field measured by the Royal Duke Cavendish.... Also masses become less gravetized to eachother in cold climates ( i.e. molecular energetics slow down a little) ... Thanks for your time... Much respect for your efforts. :)
Do you know the formula that calculates the rotation period? If your bar is too long, then it will take too long time to rotate.
Flexible plastic isn't going to do anything. Cavendish used thick walls. You could have a small aperture for a camera. The whole thing doesn't have to be transparent!
Man, it’s a bummer. I’ve been really looking forward to this for my flat vs. globe research. Thank you for trying! That’s more than most people can say for themselves. Do you think cavendish was really able to isolate these variables? Looking forward to seeing more of your content. Great work!
I'm sure Cavendish wrestled with the same types of issues. As I mentioned in the video, I think a fair bit of the issue I ran into was a result of using small, not-that-dense weights. Cavendish used giant lead balls which would have provided a significantly larger gravitational force, so his device would not have needed to be quite so sensitive.
Even so, he took the precaution of building his apparatus so that he could make all adjustments and measurements from outside, and had the torsion balance isolated from the space in which the heavy weights were moved.
Once he had everything set up, he noticed that the draw to one side or the other was not consistent over time. He eventually determined that this was due to a slight temperature difference between the weights and the balance. As the balance warmed up from being near the weights, they heated the nearby air creating a tiny air current. He described going to great lengths to identify and minimize this effect.
If you're looking to research this topic, go to the source. Here's a link to an e-book that has Cavendish's writings about his experiments:
books.google.com/books?id=zrkEAAAAMAAJ&pg=PA62#v=onepage&q&f=false
@@AndrewBennettScience Many thanks for providing the source
Don't give up!!! You can do it!! Edit: having watched the rest of the video you look really depressed, maybe keep it on the backburner and work on some less disheartening stuff. You looked very happy with the chainsaw.
I think it's awesome you built this and I wish you good luck in completing the experiment in the future. Have you considered accepting donations to help with the budget?
Thank you for this video. I'm glad to see how you protected the pendulum from external air currents. I'm amazed that it "was not enough". Actually, I don't believe that rigid walls will help at all, because if you don't see the sheet moving, how on earth stream of air could transfer its momentum inside the box? Tightening the sheet might help in that case...
I wish you had taken a footage of your erratic oscillations to give a better idea what kind of difficulties you are facing. It could be valuable example for anybody who might be interested to replicate the experiment... If the convection air currents really are the problem, cardboard box could be cheap way to test your erratic oscillations further. Maybe you should insulate the floor to get more consistent results? Cardboard might even be a good enough insulation to even out possible temperature distributions on the floor.
I was pondering what other than air currents could explain that erratic behaviour. First one was the torsion string... could it behave badly if its temperature changes? Any effect of this would probably be really small anyways. But what about the frame? If the frame moves or changes its shape e.g. due to temperature or humidity changes, can the string translate impulsive disturbance to the beam and produce such a movements?
Last hypothesis I came up with is electromagnetic disturbances. You have a lot of metal on your beam, so any changing magnetic field nearby could give it a kick. You would expect that even though electric wires running on walls are not twisted pairs, they can create only diminishingly small (changing) magnetic fields because phase and neutral wires carry the current to opposite directions. But considering the sensitivity of your setup, who knows how small magnetic fields it might be able to react to? Or could you have some household appliance nearby which has poor magnetic insulation so the strong magnetic field it generates can partly escape to its surroundings?
BTW, did you need to make the pendulum swing before you could see the erratic movement? It it were still, it never started moving by itself? Because if it didn't, does the swinging really increase the sensitivity of the device really that much that the external disturbances suddenly can have an effect when it did not while staying still... This means the external disturbance is asymmetric varies from place to place? Strong(ish) magnetic field would be necessarily uneven...
Thanks for your thoughtful response!
The idea of the temperature or humidity change affecting the line had occurred to me as well. Unfortunately, we get pretty big day-to-night temperature swings in my neck of the woods, so my garage wasn't ideal for that. Climate control might be the way to go.
I hadn't really considered magnetic effects. The bar itself is aluminum, but the weights on the end are steel, so they would certainly be subject to magnetic forces. I suppose this would be another advantage of using lead for the weights.
As for getting it still - I never got there. I tried manually adjusting the bar so that it was as close to at rest as I could manage, as near the equilibrium position as I could manage. It's tricky in that the movement is so slow as it oscillates that you can't really tell if you've adjusted it and released it from "rest" well. I would think I had it still, then run a 30 minute time lapse and find it had swiveled by a significant amount (sometimes multiple times around).
The way it moved suggested to me that the equilibrium position was not fixed in place as I had expected. I'd watch time-lapse footage to determine the middle of the swing motion, manually release the pendulum from that position, then see in the next time lapse that it would swing with a much larger amplitude around some new middle position.
My other tactic was to just let it be. I sealed off the garage from my family and myself for a full week, figuring that in that time, even the small amount of air resistance it would experience would be enough to slow it to a near stop. When I went back in and did another timelapse, the thing would be spinning circles.
The only other idea I've had since then (sadly not while it was set up, so I have no data on this) was that the knots holding the line to the hook at top and bottom were very slowly coming undone. They were tight, and with very little extra string protruding from the knot, so I think that if it had unwound at all then the entire knot should have come undone, but I think it's a possibility. If I were using heavier, denser lead weights, the torsion constant for the string would not need to be quite so small so I could use a line that's a bit thicker and would be less prone to slipping (if that was indeed what happened). I thought of adding some epoxy to the knot to make 100% sure that it wasn't coming undone.
I have some additional timelapse footage that I saved (I deleted a lot, as I was figuring I'd eventually get it working and this was just the junk I had to record to get everything set up initially). I'll post another video that just has that footage for anybody who'd like to take a look and offer their thoughts.
@@AndrewBennettScience Don't know if you are still following comments on this video, but here is another idea or two.
I had also thought of the knots. I think that's a real possibility. Also -- less likely but maybe still conceivable -- is that the fishing line is undergoing internal changes. I'm not that well versed in material science, but you have the line loaded to what, 30% of it's breaking strength? It seems possible that the plastic is undergoing creep with that much strain. And the creep might not be completely uniform, causing small torsional force changes over time.
Personally, I think a spring wire (music wire) might be a better choice. If you get .008" inch (0.2 mm) music wire, it would have a tensile strength of about 20 pounds, I'm fairly confident creep would not be an issue with steel wire, but I'd still epoxy the knots just to be sure nothing funny is happening there.
This would also give you a much lower torsion constant. Note that the elasticity of steel is basically constant regardless of how strong the steel is, and the torsional rigidity of a round rod is proportional to the radius to the 4th power. With this, I can estimate (probably fairly accurately) that the torsional constant you would get on your rig for .008" music wire would be .00002.
For an enclosure, 2 inch thick semi-rigid foam insulation panels are fairly inexpensive at any home center. You could use these on all 6 six sides (top, bottom, 4 sides) of your box, with a clear window in one side for viewing. They would also provide thermal insulation, reducing convective air currents inside the box. On second thought, you might want too keep your viewing window small (or double pane) if you use the foam. If you have just one poorly insulated area, it might increase convective circulation if there are temperature changes.
I'd use care though with sealing the box up too tight. Unless you think you can get in basically 100% air tight, there will be air entering and escaping as the temperature and barometric pressure change. If you have only one or two small holes, you might get jets of air entering. I'd suggest a bit larger vent, maybe dead-center in the top, covered with a few layers of rag or something to diffuse any air entering. A moderate sized hole will mean the air will enter more slowly than with a tiny hole, so it will have a lot less energy. A single hole means you won't get air blowing in one and out the other if there are air currents in the room.
In 1917, Professor Francis E. Nipher applied a low frequency A/C current to a modified Cavendish apparatus, with which he was able to control the attraction, as well as repulsion.
What were the materials used? and what was the intention of this?
Any update on this experiment for this summer? Still trying to prove gravity in my FE research! Haven’t seen cavendish experiment actually succeed. Thanks
it has succeeded, you should look better. You don't need it tho, because the fact that everything falls towards earth at the same rate regardless of its mass, is sufficient. FE is debunked by the sunset which is a lot more simple than gravity. Nothing to research.
@@GMDimitrov Sorry, I'm of the opinion objects don't fall at the same rate regardless of mass. An object falls due to a property of the object itself than any external force or influence acting on it. Heavier objects will ALWAYS fall faster than lighter ones given enough height is allowed for all objects to reach their maximum drop velocity. Try it for yourself, do several drop tests in air, in water and in vacuum and you'll get the same results. And don't come back with the Brian Cox demo at NASA because one never sees the drop in one single take. It's a contrived video presentation. I've done 2m vacuum drops and the heavier objects hit the bottom first. The Earth is Flat and welcome to man's fabricated world!!!
Peter & Pete No object will move in a certain direction unless a force acts on it. To lift an object to a certain height above the ground, you must apply a force. For that object to fall back down when dropped, there must also be a reason or a force. That force is the force of gravity. An object with a larger mass will fall faster because the force of gravity acting on it is bigger than the force of gra vity acting on an object with a smaller mass. This means that the more massive object will reach a higher terminal velocity which is the point where the force of gravity and air resistance which is trying to slow the object down are equal but acting in opposite directions. Two identical sheets of paper have the same mass but if one is squished into a ball it will fall faster. However, when talking about falling at the same rate, it’s not the speed that is equal, it’s the acceleration, which is exactly 9.8 m/s^2 and is the same for all objects free falling in a vacuum regardless of their mass. Same goes for two cylinders of different mass that roll down a sloped surface. One can be gigantic, the other one can be tiny, it doesn’t matter. As long as both are solid, they finish at the same time. Walter Lewin demonstrates this during his physics lectures at MIT and my physics teacher in school did it too so I’ve seen it. The NASA vacuum chamber video clearly shows the feathers and the ball hitting the ground at the same time. There are videos of other experiments too, all showing the same result, so you must have done something wrong. As I said in my previous comment, the Earth cannot possibly be flat because sunsets.
@@GMDimitrov quote - To lift an object to a certain height above the ground, you must apply a force. For that object to fall back down when dropped, there must also be a reason or a force. That force is the force of gravity.
Noooo! That is not the force of gravity causing objects to fall, that's only what you THINK is the cause. You can't even prove your causation is true anyway!
I'm still of the opinion (because you haven't convinced me), every object has inertial mass (see einstein's equilibrium principle) and by raising an object one is also attributing the object with the 'potential to fall'. So by raising an object one is giving the object the reason to fall. Falling objects imo fall not due to gravity but simply because of an object's inertial mass and its potential to fall!
We've watched the walter lewin video using a ramp and cylinders of different materials. You clearly overlooked the part when a lighter aluminium cylinder hit the bottom of the ramp BEFORE the heavier cylinder! The reason why this happened is that a lighter object will always reach its max drop velocity quicker than a heavier one and this is why people can be FOOLED or convinced into thinking objects fall at same rate (see action lab's vidoe of feather/metal cube in a vacuum falling at a height of only around 18inches)! Clearly extend the height to allow BOTH heavier and lighter objects to reach max drop velocity then heavier object will ALWAYS hit bottom first!
@@GMDimitrov Gravity is only an IDEA that describes falling motion but it's not the reason WHY objects fall!
This test should be done in a vacuum chamber.
thats a big vacuum chamber
I've seen this comment before. While I agree that a large vacuum chamber would eliminate any problems I might have had with air movement, I simply don't have access to something like that. Also, it seems reasonable to me that I could get decent results without, given that Cavendish did this experiment before anybody had vacuum chambers.
Jss its strange in 220 years nobody did it on a vacum chamber.
@@IgotQuestions. noit really when you consider that scientists have better ways to measure it now
@@IgotQuestions. University of Washington has done it in a vacuum chamber, wouldn't be surprised at all if some others have too.
Flat earthers are going to have a field day with this...
U have to enclosed in a glass chamber , and the big mases left outside
Why can't the big masses be inside? What does gravity have to do with glass versus plastic covering? Does it have something to do with static charges? Thanks
How can I calculate the period??
Please research lasers over 40 miles of water and no detectable curvature
Funny, I do exactly the same thing right now.
What were your results? Do you have any videos?
@@FreedomFirst925 Yes, I have three videos. They all show that Newton was wrong and Gravity in fact comes from quark number and not mass. I will upload more this month.
And now we have the Coronavirus Pandemic...
total waste of time, money and effort! if you can't do it in 2019 (blaming it on a whole list of problems you've encountered) and Cavendish did do it around 223 years ago one has to ask whether gravity is a real force? I think not as all the cavendish experiment most likely demonstrates is suspended objects of different masses can move! Why they move could be a result of anything but certainly not this thing called gravity!
Says the flat earth believer! 🤣
Sorry to hear you had to terminate the experiment. I'm setting up a smaller one right now and would love your input on problems you ran into. I just did an update on my experiment today. I'm also hoping to do a livestream with some other creators to trouble shoot possible failure points. If you ae free you are welcome to join. ruclips.net/video/kkWdQUp4GOw/видео.html