I've never seen a rectangle represent angular momentum before. I suppose you could use this technique in other explanations involving "conserved" products. Great job!
Yes, you can use a parallelogram for any physical quantities involving cross product. I explain this in my video "Cross Product and Dot Product" at ua-cam.com/video/h0NJK4mEIJU/v-deo.html
You need to look into geometric algebra then, mate you gonna lovevit. you can represent all sorts of physical concepts as bivectors or oriented volumes of.higher order.
This is kind of the point of geometric algebra. You Should look into it. There is also very cool videos on the subject on youtube. This also leads to spacetime algebra.
What blows my mind (not covered in this video) is that angular momentum is conserved even when the centripetal force suddenly vanishes. Say one of the spheres breaks away and flies off with constant linear velocity. The distance between the sphere and axle will grow, but the angle of the sphere-axle vector will change at a rate inversely proportional to the square of that distance, keeping the area of the rectangle constant. "The laws of physics hold, even when they don't."
I also find that example to be quite extraordinary. There is a nice symmetry it seems that you can derive laws of linear motion from that of angular motion and vice versa.
Always love your videos. I've been arguing for years with peers that rotation doesn't require a special, independent angular version of momentum. That it's just an consequence of linear behaviors, and using angular momentum is just a simpler way to handle the math. The animations you make do a great job of building on core principals to show these complex interactions. Thank you!
Congratulations on you million subscribers!!! Many more to go. Your video unboxing the plaque was very entertaining, very refreshing to have it unscripted and unedited, more human and enjoyable. Kira, thanks for granting us a glimpse of your face, at last we can put a real face to all those characters you've voiced, great career.
Angular momentum has always been (in Newtonian mechanics) a derived one. One can see this in the formula as it's dependent on other factors (ie. "r" and "p"). By the way, congratulations on 1M! Love your videos.
For balls to move closer to the centre, an extra force for a short time TOWARDS the centre has to be applied, since force is towards the centre and balls also move towards the centre therefore some work is done ON the system, thus the system must gain energy, since there is no translation involved (as net force on both balls is zero), the extra energy supplied manifests as increase in the velocity of balls.....
Yes, this can also be viewed in terms of conservation of energy. Another way to think about it is the potential energy in the spring transformed into the kinetic energy of the spheres. But, as I said at the beginning, Newton's Laws of motion don't actually say anything about conservation of energy. Therefore, it is interesting to show how all this behavior can be thought of exclusively in terms of Newton's second law of motion.
Congrats on the 1M subscribers, yet you deserve a lot more subscribers and views! So many schools could make learning easier by showing your videos, they make it much easier to intuitively understand what looks like abstract concepts on paper. One way you could increase your reach is by translating the videos to other languages, especially Spanish, Chinese and maybe French (not sure which languages are used the most). It might be a lot of work as you'd have to redo most of the text that's part of the video, and the voice over, but it might be worth it.
Thanks for the compliments. Many of my videos already have subtitles available in other languages. To see subtitles in other languages: Click on the gear symbol under the video, then click on "subtitles." Then select the language (You may need to scroll up and down to see all the languages available).
Your animations are really helpful. Just before this I watched the illuminating video on the weak force. Next up: cosmic angular momentum and quantum spin
I used to watch some videos of this channel, they were 9 years old, I thought they probably stopped filming- knowing guys are still posting made my day! I still have more to watch and the production is ongoing ❤🎉
I love how your videos feel so unique and abstract and bizarre in the good sense if that makes any sense I like to imagine and think of the world you created with it's infinite grid and the vectors and the weird cats and humans it's so amazing sometimes I enter some of your videos am not ready to understand yet just to feel amazed by the magical world you have built
this is like orbital mechanics right? i remember learning this intuitively when playing outer wilds. while trying to land on the sun station i realized that moving closer to the sun made me orbit faster and moving away slowed me down.
I think one way of thinking about the rotational equations of motion (at least for the case of rotation about a fixed axis, eg Torque = momentum of inertia times angular acceleration) is that this law is Newton’s second law combined with the constraint that v = r times omega. In other words, it’s not necessary to use torque = I times angular acceleration, it’s just convenient because it’s easy to combine Newton’s second law + the constraint into this one equation.
Thanks for the video ! @3:46 I don't get the part where you say that a force must oppose the centrifuge (centipede ?) force with a constant force going towards the center. When we use a bar to maintain the spheres attached to the center, must we consider that a simple bar is equivalent to a constant acceleration ? If yes, is not constant acceleration supposed to consume energy constantly ? So, that any object is constantly consummling energy juste to exist ?
This does not consume energy because the energy transferred is the force multiplied by the distance travelled in the direction of the force. Since the force and the incremental distance travelled are always 90 degrees to each other, no energy is transferred.
Big fan of the channel. however IMO, the "brief extra force" argument could have been elaborated much better: Hmmm.. let's see: avoid momentary force imbalance by applying the extra force force to both spheres with their radial coordinates as their only DOF; also, forbid any "recoil" form otherwise present system of forces (for example using *friction* brakes on the rods connecting the two spheres). In this case, *which is the most similar to the video* that I can think of, the spheres would accelerate RADIALLY towards (or away from) the center of rotation, if (like in the video) applied radially. This would result in a momentarily spiraling motion, due to altered radial velocities. But would it span exactly _a quarter turn_ as shown? The accelerated motion can end up *all tangential* precisely when the spheres happen to move perpendicularly to the force application direction, so after a quarter turn. At all other times, however, while the spheres' velocities do not align with the direction of application and the radial components of the added momenta change the motion's radius, the tangential components would cause deceleration/acceleration TORQUE on the rods maintaining the spheres in a circular motion (well, "circular" except when they're spirals). Finally, these tangential components would be zero with the rods at 90° with the initial force, so a quarter turn after, and the spheres wouldn't accelerate any more so *yes it's a quarter turn* ! (gyroscopic stability/precession explained ! 😀) THEN, by removing the friction brakes on the rod, and adding back the springs' recoil (or a 1/R^2 force 🙂 ) we end up with elliptical "orbits". Nay, remove the hyphens: it's elliptical ORBITS....!
For the example of a short force in/outward being necessary to change the radius of rotation, i dont understand how that leads to the linear momentum magnitude being decreased througout the whole rotation. In your example for instance, at the point when the short force is applied the linear momentum is pointing upwards. Shouldnt we expect then that the linear momentum points outward at some angle not tangent to the path?
My mentor Please make a video on how does whistles work and what is the movement of molecules in different types of (mechanical) whistles. Please tell me will you make one animation of that?
I don't think your audience realizing just how fundamental of a generational physics description run you're on, you have properly framed so many concepts of physics in the correct and post-modern understanding of physics that doesn't lack the actual optimal intuitions required to think about it in the real world... THIS UA-cam CHANNEL IS GENERATIONALLY LEGENDARY
When people begun talking about conservation of energy? Also, why Lagrange defined the lagrangian as T-K? What was the inspiration that made him notice that this would work?
@@EugeneKhutoryansky Thank you, it looks to me that it has taken so much time to create animation. I also explain advanced topics related to particle physics.
Didn't Newton mention something about inertia being to do with internal forces ? 🤔 So, perhaps this angular momentum is the net result of the relative changes of the central force and actual changes of these internal forces wrt a particular orbiting mass? 🤔💭💡
If you applied the force when the ball was on the left, though, wouldn't it look like pushing it left to give it a wider orbit would have sped it up? I know that's not really the principle you're showing because of the sign of the cross product, but that's what it _looks like_ you're showing.
The issue is whether the extra force is towards or away from the center. It does not matter whether if it is while the ball is on the right or left side. If you watch my animation with the monitor rotated 180 degrees, then the force would change from when the ball is on the right side to when it is the left side, but the animation would still be the same as before, but with the monitor rotated 180 degrees.
A force applied separately from the existing circular motion system. In order for a body in constant circular motion to move to a different radius of rotation, some new force must be applied.
I don't yet have a video dedicated to String Theory, but I mention String Theory in my video on the Multi-Verse at ua-cam.com/video/Y4NktqDjYXs/v-deo.html
It was, although it may not look like it. Say you nudge the ball outwards. Since that nudge is perpendicular to the momentum, it will rotate the momentum outwards. But then the momentum won't be perpendicular with the centripetal force anymore. Remember the only reason it kept perpendicular was because the centripetal force and the momentum were "balanced" to form an (equidistant) "orbit". Now part of the centripetal force will counter act this part of the momentum which is pointing "outwards", besides rotating the momentum, which will eventually kill this outward momentum, reducing the total momentum (since originally you only had a shift, assuming an effectively instantaneous nudge). Note that in this part of the motion the centripetal force was actually in the direction of the rate of change of linear momentum. The result is then a new "balanced" orbit, with smaller linear momentum but larger radius. The same kind of thing happens when the nudge is inwards, only the momentum is rotated inwards and for a while the centripetal force increases this momentum as the ball comes closer to the center, until things balance out again. Note that the same main ideas are also at work in, say, planetary orbits, or stuff like the two balls connected by a spring, even though in these cases the centripetal force is also dependent on the distance, which complicates things, but still ends up conserving angular momentum and total energy.
In the animations where the spheres are connected with springs, the yellow arrows are the total momentum, with both tangential and radial components. In the animations where the spheres are connected with a solid cylinder, the yellow arrows just show the tangential momentum, though here the radial component of momentum is typically zero, except for the brief moments when the spheres are changing their radius of rotation.
Can you explain why everything in the universe spins? From subatomic particles, to galaxies. Always spinning! Nothing in the universe is stationary. Is there a spin theory like the M theory?
subatomic particles dont spin, they "spin." Everything else in the universe spins because in the early universe when matter amalgamated, the momentum from the compaction was conserved.
The spin of subatomic particles has nothing to do with actually spinning. It's just a name we give it, since there is angular momentum due to bodies having this property.
Hi, Eugene, thanks for some great insights. You have some videos that really helped me a lot understanding some things. But since having seen a lot of other channels I'd suggest getting a bit more modern in some aspects - maybe you get an idea of what I could mean. If interested in details simply ask. What I will never understand why all animations are so FAST. There are things that have to be understood step by step - and they do as if there was no tomorrow. I had to slow down this video to 1/4 of speed in order to watch the arrows grow and shrink and THIINK about what I see. Unfortunately there are some aspects I simply do not get. For example: Why do the rotating spheres with the spring have momenta that do not change direction most of the time? Why do they rotate only while turning around? Shouldn't they change direction instantly? You answer some interesting aspects but leave open so many questions regarding what you show - is this intended? There habe been some videos in the nearer past where I have noticed this effect of rising more questions than answering... Have you ever corrected a video? I ask as I have seen a video about theory of relativity which the author claimed in that you, Arvin Ash, Sabine Hossenfelder, PTBS-Space time and many more have been wrong and he had good arguments. Unfortunately at the moment I have no clue who the person is... But of course in the videos here things are covered that are topics of debates and to some extent this should be part of your videos? Don't get me wrong: Of course physikcs is nothing that's debatable by itself - but our knowledge or understanding of it has undergone some changes and this process is going on - so more debate aspects should be included in some videos. Does ANYONE really know what's ging on with space and time? And what to think about the Schwarzschild metric for example which is at it's best some approximation of the real things. How can we, one or you speak about those things as if they were without unknown or unclear aspects? This is wondering me more an more... Regards!
@@WajihaHaleema-bk8xq I did not talk about relegion in any way. It was pure physics here. I talked about Schwarzschild and Hossenfelder... Both have no direct relation to any religion.
Angular momentum is constant ONLY if there are no external forces acting on it -- if a motor were to spin the system up to double the angular velocity the angular momentum would NOT remain constant!
It's really no net torques. Angular momentum is still conserved on a system of bodies, freely falling in a uniform gravitational field. It's also conserved if there are external forces, but they add up to zero. Or if there are external forces, but they are so brief that their impulse is insignificant.
@@ricomajestic You're playing word salad games. If the forces sum to zero there is no net force. If the torques sum to zero there is no net torque. The angular momentum of a system remains constant so long as no external forces act on it, but if external forces are acting on it resulting in a net torque then the angular momentum will/must change! Those are the rules!
@@Raptorman0909 "External forces that sum to zero is EXACTLY the same thing as NO EXTERNAL FORCES AT ALL." This is what you said initially which is wrong!. A system where there are no external forces is not the same as a system where the forces sum to zero. The net force on an object would be the same but the net torques might be different in those two cases! An object where there are no external forces acting on it cannot have a net torque however an object who's external forces add up to zero can have a net external torque so they are not equivalent statements. What you call "word salad' can actually be critical to the motion of a structure or if you want to prevent it from moving. So you indeed need to worry about correct language in science!
Do you know that conservation and Newton's laws work only in absolute time. In variable time, for example, Newton's 3rd law should be adjusted like that: F1×D1²=-F2×D2², where D is time dilation factors. Read details in "Time Matters, 9th edition".
@@EugeneKhutoryanskyIf the radial force nudges the sphere radially inwards as the sphere rotates there is now a component of the spring force in the direction of motion, which increases the linear speed of the sphere, which in turn increases the angular momentum? Similarly, the spring force has a component opposing the motion when the sphere moves radially outwards?
Centrifugal force doesn't exist. It is only there to explain why an object does not fall toward the center from the object's own reference frame, where the linear velocity is zero. It doesn’t exist in all reference frames. For example, between the sun and the Earth, gravity is the centripetal force for the Earth orbit, and it is the only force.
Sorry, but I think it's you Mysoi, that's slightly mistaken. Gravity is not a force either. The centripetal and centrifugal forces in orbital motion, are both apparent forces, which only appear in an accelerated frame of reference. Any celestial body in space is moving on a geodesic path, or the nearest thing to a straight line in a curved space-time. Which means the net acceleration at it's centre is zero. The point where the centripetal and centrifugal effects cancel.
@@cybermonkeys I learned the Einstein field equation, differential geometry, and tensor concepts, but in the context of the Earth/Sun, Newton’s model is sufficient. Also, when explaining to someone, we have to know their level of understanding in order to enlighten them.
@@Mysoi123 Yes, and I totally agree, but in Newtonian Mechanics, both the gravitational (centripetal) and centrifugal forces both exist. That is the reason why the Earth and Moon, both orbit around their common centre of mass. Exactly the same for the Earth-Moon system around the Solar System barycentre. It's not as easy as just saying Centrifugal Force does not exist, but I understand where you're coming from. Have a great day my fellow physicist.
@@cybermonkeys That is not true; you cannot say both forces exist. For example, if you're inside floating around in a box, when the box accelerates, you will not move along with the box immediately. Instead, you will move only when the box hits you, and a force acts on you to accelerate you together with the box. From your frame of reference, the box is standing still, >>it is not moving
4:43 This bit isn't quite making sense to me. You stopped the rotation 90 degrees after the force was applied, then made it look as if the two red arrows pointing in the same direction were somehow significant - but it can't be significant, because when the force was applied, the motion was at 90 degrees to it. I mean, I understand that angular momentum is conserved, I get that - but there seems to be a step missing from the explanation. WHY does a radial force change the linear speed? There's nothing here that explains that clearly.
The issue is whether the extra force is towards or away from the center. It does not matter whether if it is while the ball is on the right or left side.
@@EugeneKhutoryansky Thank you for trying to help me understand, but I'm still confused. The animation appears to show the force applying to the left, and the ball has moved to the top position by the time the arrow is shown. I'm still unable to understand what you're trying to convey with this animation. Somehow a radial force translates to an increase in angular speed: I understand that, but I can't grasp how it's happening, and the fact that the red arrows both point to the left feels like a distraction.
Angular momentum force vector yellow conserved rectangle purple shrink red blue constant force brief extra greater linear force rotating newton yellow teacher ji
It is also highly useful to consider whether a given system conserves angular momentum or not. If we know that it does before jumping into calculations, we can save a lot of work. If we know that it doesn't, we can consider where and why.
@@narfwhals7843 can you give a simple example in which angular momentum is not conserved? because the principle says that angular momentum is always conserved - if there is any (for a specific frame of reference)!
@@orfeaskar3717 Conservation laws usually apply to closed systems. If we consider a system with an external force, usually conserved quantities may not be conserved. Say the system is a weather vane by itself. If we consider the wind to be an external force, this will change the angular momentum of our system. Of course we can include the wind into our system and momentum is again conserved, but knowing what is "internal" and what is "external" is a useful tool for calculations and knowing what we can ignore or what we should have included. In general, angular momentum is conserved for systems where the physics does not depend on the orientation. (Noether's Theorem).
Are the red forces “imaginary?” In this context of angular momentum? Sorry Im a layman. The spheres just “want” to travel in a linear path and the different imaginary forces depend on how close or far the balls rotate around each other? Thank you for your videos.
@@EugeneKhutoryansky thanks, but this video doesn't explain the general relativity case for the angular momentum conservation. I guess it's not an easy problem.
Re: the first system to consider -- as soon as you have mass, you have gravity. This is also why special relativity is wrong from the get go. Luckily general relativity wasn't built right on top of special relativity. Wait, what?
Special Relativity Is not wrong from the get go. Einstein did not consider acceleration in SR, it was only concerned with the constant motion of objects in a straight line, or Inertial frames of reference, or the principle of inertia. When he began thinking about acceleration, or non-inertial frames of reference, then he realised that gravity was just the accelerated motion, that only appears in an accelerated frame of reference. Very similar to the appearance of the centrifugal force in Newtonian Mechanics.
@@FloydMaxwell Well, now you're talking about single atoms, which reaches into the realms of Quantum Mechanics, where gravity doesn't play very well with the known equations. Gravity and acceleration aren't two separate things. Gravity is an apparent force that only appears in an accelerated frame of reference. Special Relativity Is not worthless, because it evolved our understanding of Space and Time, which we're not absolute, like Newton had suggested in his Principia.
You describe the linear velocity of the spheres changing as the distance from rotational center is changed. This is not true from how I understand it. The velocity stays the same, it's just that the circumference of its path is smaller, so it completes each orbit faster.
@@EugeneKhutoryansky The circumference of a circle is 2(pi)r. Therefore if the radius is cut in half, so will be the circumference. As per your video, the momentum of the sphere can be described by the area of a rectangle with sides (radius) and (velocity). If radius is halved, velocity must double to maintain the area. So you are saying that a sphere traveling in a circle that is then pulled in to now travel in half the radius, will necessarily orbit 4 times faster (twice the velocity around half the distance)? That is not the way I previously thought of it, but I will have to try an experiment. Always good to learn something new.
Congratualtions to one million subscribers. It is well deserved.
Thanks.
Yes, agreed! Congrats, Dr. K!
If only there was something similar for Chemistry 😏
I've never seen a rectangle represent angular momentum before. I suppose you could use this technique in other explanations involving "conserved" products. Great job!
Yes, you can use a parallelogram for any physical quantities involving cross product. I explain this in my video "Cross Product and Dot Product" at ua-cam.com/video/h0NJK4mEIJU/v-deo.html
I hope you have seen the area proof of kepler's laws too. It is of the same essence.
You need to look into geometric algebra then, mate you gonna lovevit. you can represent all sorts of physical concepts as bivectors or oriented volumes of.higher order.
This is kind of the point of geometric algebra. You Should look into it. There is also very cool videos on the subject on youtube. This also leads to spacetime algebra.
This is the idea of a bivector, which is the right representation of angular momentum
What blows my mind (not covered in this video) is that angular momentum is conserved even when the centripetal force suddenly vanishes. Say one of the spheres breaks away and flies off with constant linear velocity. The distance between the sphere and axle will grow, but the angle of the sphere-axle vector will change at a rate inversely proportional to the square of that distance, keeping the area of the rectangle constant. "The laws of physics hold, even when they don't."
In that case, it is no longer a rectangle but a parallelogram. I cover that in my other video, which I mention at the end of this video.
I also find that example to be quite extraordinary. There is a nice symmetry it seems that you can derive laws of linear motion from that of angular motion and vice versa.
These visuals and explanations honestly just changed my mind about torque and horse-power in cars. Hats off to your work, as usual 👏
Thanks.
Thank you so much for your huge contribution in understanding physics and the world around us.
Thanks.
The bivector representation cleared a whole mountain for me
Always love your videos. I've been arguing for years with peers that rotation doesn't require a special, independent angular version of momentum. That it's just an consequence of linear behaviors, and using angular momentum is just a simpler way to handle the math. The animations you make do a great job of building on core principals to show these complex interactions. Thank you!
Thanks!
* core principles
So many low IQ physics "experts" don't seem to understand this.
Have you forgotten how angular mechanics is derived? It's all from linear mechanics.
@@Lolwutdesu9000 no, i haven't, but i've had tons of debates with others on angular momentum being it's own thing independent of anything else.
Angular momentum seemed to be a bit mysterious to me until I watched this video. Nice, simple, and clear explanation.
Thanks. I am glad my video is helpful.
yea but u cannot derive conservation of angular momentum from newtons laws. but animations are beautiful and enjoyable
Always enjoyable and beautiful animations. Congratulations Eugene.
Thanks for the compliments about my animations.
Congratulations on you million subscribers!!! Many more to go. Your video unboxing the plaque was very entertaining, very refreshing to have it unscripted and unedited, more human and enjoyable. Kira, thanks for granting us a glimpse of your face, at last we can put a real face to all those characters you've voiced, great career.
Thanks!!!
Angular momentum has always been (in Newtonian mechanics) a derived one. One can see this in the formula as it's dependent on other factors (ie. "r" and "p"). By the way, congratulations on 1M! Love your videos.
Thanks!
@@EugeneKhutoryansky You're a legend.
For balls to move closer to the centre, an extra force for a short time TOWARDS the centre has to be applied, since force is towards the centre and balls also move towards the centre therefore some work is done ON the system, thus the system must gain energy, since there is no translation involved (as net force on both balls is zero), the extra energy supplied manifests as increase in the velocity of balls.....
Yes, this can also be viewed in terms of conservation of energy. Another way to think about it is the potential energy in the spring transformed into the kinetic energy of the spheres. But, as I said at the beginning, Newton's Laws of motion don't actually say anything about conservation of energy. Therefore, it is interesting to show how all this behavior can be thought of exclusively in terms of Newton's second law of motion.
Nice summary
Congrats on the 1M subscribers, yet you deserve a lot more subscribers and views! So many schools could make learning easier by showing your videos, they make it much easier to intuitively understand what looks like abstract concepts on paper.
One way you could increase your reach is by translating the videos to other languages, especially Spanish, Chinese and maybe French (not sure which languages are used the most). It might be a lot of work as you'd have to redo most of the text that's part of the video, and the voice over, but it might be worth it.
Thanks for the compliments. Many of my videos already have subtitles available in other languages. To see subtitles in other languages: Click on the gear symbol under the video, then click on "subtitles." Then select the language (You may need to scroll up and down to see all the languages available).
It seems a small step from this to show that angular momentum must be conserved if the laws of motion are to be independent of orientation.
The real excitement of science is we get different interpretations for each topic and attaining the moment of brilliance
Thanks.
I'd like to see Hamiltons coined as the name of the momentum unit, and Keplers coined as the name of the angular momentum unit.
Very important and infomative.The way of explaining using vectors by arrow as well as by area is appreciable.
Thanks.
Your animations are really helpful. Just before this I watched the illuminating video on the weak force. Next up: cosmic angular momentum and quantum spin
I am glad my animations are helpful. Thanks.
Ur 1 million subscribers gave me genuine happiness :)
Nice video also.
Thanks!
I used to watch some videos of this channel, they were 9 years old, I thought they probably stopped filming- knowing guys are still posting made my day! I still have more to watch and the production is ongoing ❤🎉
I never stopped. More videos are on their way.
I love how your videos feel so unique and abstract and bizarre in the good sense if that makes any sense I like to imagine and think of the world you created with it's infinite grid and the vectors and the weird cats and humans it's so amazing sometimes I enter some of your videos am not ready to understand yet just to feel amazed by the magical world you have built
Thanks for the compliments. I am glad you like my videos.
These are great explanations. Keep 'em coming.
I am glad you like my explanations. More videos are on their way.
Ah, my favorite returns! Thanks for this intuitive explanation
Thanks.
Never thought of it as a rectangle but it makes perfect sense
I love watching these animations with the vectors. Even after understanding this it is still magical to watch.
I am glad you like my animations. Thanks.
That's a really clever animation. Kudos!
Thanks.
Please talk about geometric algebra and how it simplifies the interpretation of physical quantities.
this is like orbital mechanics right? i remember learning this intuitively when playing outer wilds. while trying to land on the sun station i realized that moving closer to the sun made me orbit faster and moving away slowed me down.
Have you ever played kerbal space program? You can also learn a lot about orbital mechanics there
Best explanation of angular momentum I've seen. Thanks!
I am glad you liked my explanation. Thanks.
4 mins in and now I'm hypnotized.😵💫
Excellent video by the way.
Thanks.
I think one way of thinking about the rotational equations of motion (at least for the case of rotation about a fixed axis, eg Torque = momentum of inertia times angular acceleration) is that this law is Newton’s second law combined with the constraint that v = r times omega. In other words, it’s not necessary to use torque = I times angular acceleration, it’s just convenient because it’s easy to combine Newton’s second law + the constraint into this one equation.
I was really amazed by the quality of the animation and the maturity of the concept
Thanks.
Angular momentum is a really nice concept, and your explanation is amazing.
I am glad you like my explanation. Thanks.
It's very humble that you reply even after having 1M subscribers. ❤
congrats on one million subscribers!
Thanks.
Thanks for the video !
@3:46 I don't get the part where you say that a force must oppose the centrifuge (centipede ?) force with a constant force going towards the center. When we use a bar to maintain the spheres attached to the center, must we consider that a simple bar is equivalent to a constant acceleration ?
If yes, is not constant acceleration supposed to consume energy constantly ? So, that any object is constantly consummling energy juste to exist ?
This does not consume energy because the energy transferred is the force multiplied by the distance travelled in the direction of the force. Since the force and the incremental distance travelled are always 90 degrees to each other, no energy is transferred.
Nice explanation
Thanks. I am glad you liked my explanation.
Big fan of the channel. however IMO, the "brief extra force" argument could have been elaborated much better: Hmmm.. let's see: avoid momentary force imbalance by applying the extra force force to both spheres with their radial coordinates as their only DOF; also, forbid any "recoil" form otherwise present system of forces (for example using *friction* brakes on the rods connecting the two spheres). In this case, *which is the most similar to the video* that I can think of, the spheres would accelerate RADIALLY towards (or away from) the center of rotation, if (like in the video) applied radially. This would result in a momentarily spiraling motion, due to altered radial velocities. But would it span exactly _a quarter turn_ as shown? The accelerated motion can end up *all tangential* precisely when the spheres happen to move perpendicularly to the force application direction, so after a quarter turn. At all other times, however, while the spheres' velocities do not align with the direction of application and the radial components of the added momenta change the motion's radius, the tangential components would cause deceleration/acceleration TORQUE on the rods maintaining the spheres in a circular motion (well, "circular" except when they're spirals). Finally, these tangential components would be zero with the rods at 90° with the initial force, so a quarter turn after, and the spheres wouldn't accelerate any more so *yes it's a quarter turn* ! (gyroscopic stability/precession explained ! 😀) THEN, by removing the friction brakes on the rod, and adding back the springs' recoil (or a 1/R^2 force 🙂 ) we end up with elliptical "orbits". Nay, remove the hyphens: it's elliptical ORBITS....!
For the example of a short force in/outward being necessary to change the radius of rotation, i dont understand how that leads to the linear momentum magnitude being decreased througout the whole rotation.
In your example for instance, at the point when the short force is applied the linear momentum is pointing upwards. Shouldnt we expect then that the linear momentum points outward at some angle not tangent to the path?
Extra linear momentum away from the center of rotation becomes linear momentum tangent to the rotation 90 degrees later.
Congratulations on 1M subs 😃😃
Thanks.
Thanks for sharing
Great video. What is the name of the composition in the background?
CanCan_by_Offenbach from the free UA-cam audio library. Thanks for the compliment about my video.
Always enlightening 👏
Thanks.
Always waiting for video my teachers can't explain like this.
❤
Thanks.
Welcome 🤗
Fantastic 🎉which program used to generate this please ?
Thanks. I explain how I make my 3D animations in my video at ua-cam.com/video/6Hl5dvA88Uo/v-deo.html
My mentor Please make a video on how does whistles work and what is the movement of molecules in different types of (mechanical) whistles. Please tell me will you make one animation of that?
Also please make one video on the detailed simulation of vortex tube refrigeration.
I will add those topics to my list of topics for future videos. Thanks.
Nice animation! 👍
Thanks.
Very good presentation.
Is it also true that "Energy" also does not appear in Newton's works?
Thanks. Energy is not in Newton's 3 laws of motion.
Missed your relatively longer videos though..
thank you for your job!
Thanks.
Класс наблюдать это! Спасибо большое за Ваш ТРУД!
Спасибо.
I don't think your audience realizing just how fundamental of a generational physics description run you're on, you have properly framed so many concepts of physics in the correct and post-modern understanding of physics that doesn't lack the actual optimal intuitions required to think about it in the real world... THIS UA-cam CHANNEL IS GENERATIONALLY LEGENDARY
Thanks for the compliments.
When people begun talking about conservation of energy?
Also, why Lagrange defined the lagrangian as T-K? What was the inspiration that made him notice that this would work?
The minus sign follows directly from Newtons 2nd law.
Very nice explanation 😀
Thanks. I am glad you liked my explanation.
@@EugeneKhutoryansky Thank you, it looks to me that it has taken so much time to create animation. I also explain advanced topics related to particle physics.
Didn't Newton mention something about inertia being to do with internal forces ? 🤔
So, perhaps this angular momentum is the net result of the relative changes of the central force and actual changes of these internal forces wrt a particular orbiting mass? 🤔💭💡
If you applied the force when the ball was on the left, though, wouldn't it look like pushing it left to give it a wider orbit would have sped it up? I know that's not really the principle you're showing because of the sign of the cross product, but that's what it _looks like_ you're showing.
The issue is whether the extra force is towards or away from the center. It does not matter whether if it is while the ball is on the right or left side. If you watch my animation with the monitor rotated 180 degrees, then the force would change from when the ball is on the right side to when it is the left side, but the animation would still be the same as before, but with the monitor rotated 180 degrees.
Which tools or software u use to make videos like these ?
I explain how I make my 3D animations in my video at ua-cam.com/video/6Hl5dvA88Uo/v-deo.html
What is the brief extra force.
A force applied separately from the existing circular motion system. In order for a body in constant circular motion to move to a different radius of rotation, some new force must be applied.
Can you tell me about the software you use to create those videos?
I explain how I make my 3D animations in my video at ua-cam.com/video/6Hl5dvA88Uo/v-deo.html
What happens if you make it longer during a VERY long time or during a VERY short amount of time?
it seems that angular momentum is somehow more fundamental than velocity or spin, even though it can be explained by those components working together
13 hour 10 thousands views, bro never gonna fall
Btw congrats for 1 million subs dr :)
Thanks.
eye catching animations
Thanks.
I love your videos
Thanks. I am glad to hear that.
Is there any video about string theory?
I don't yet have a video dedicated to String Theory, but I mention String Theory in my video on the Multi-Verse at ua-cam.com/video/Y4NktqDjYXs/v-deo.html
But wait. That brief force was not in the direction of the rate of change of the linear momentum, as Newtin's second law states.
It was, although it may not look like it.
Say you nudge the ball outwards. Since that nudge is perpendicular to the momentum, it will rotate the momentum outwards. But then the momentum won't be perpendicular with the centripetal force anymore. Remember the only reason it kept perpendicular was because the centripetal force and the momentum were "balanced" to form an (equidistant) "orbit".
Now part of the centripetal force will counter act this part of the momentum which is pointing "outwards", besides rotating the momentum, which will eventually kill this outward momentum, reducing the total momentum (since originally you only had a shift, assuming an effectively instantaneous nudge). Note that in this part of the motion the centripetal force was actually in the direction of the rate of change of linear momentum.
The result is then a new "balanced" orbit, with smaller linear momentum but larger radius.
The same kind of thing happens when the nudge is inwards, only the momentum is rotated inwards and for a while the centripetal force increases this momentum as the ball comes closer to the center, until things balance out again.
Note that the same main ideas are also at work in, say, planetary orbits, or stuff like the two balls connected by a spring, even though in these cases the centripetal force is also dependent on the distance, which complicates things, but still ends up conserving angular momentum and total energy.
“Please subscribe for notifications when new video is ready”
First UA-camr to tell the true use of subscription
Islam is a relgion of science. Why don't you accept islam?
Tell me why aren't you replying. Tell me so that I may know what is keeping you from doing so. If it is my fault. I will figure the solution out.
great video
Thanks for the compliment.
Excellent video, but the music is too loud.
Mass and velocity have a similar relationship?
STILL UPLOADING LIKE A BOSSSSSSS
Thanks.
But it should be some slowly
The yellow arrows are the tangential momentum, correct?
In the animations where the spheres are connected with springs, the yellow arrows are the total momentum, with both tangential and radial components. In the animations where the spheres are connected with a solid cylinder, the yellow arrows just show the tangential momentum, though here the radial component of momentum is typically zero, except for the brief moments when the spheres are changing their radius of rotation.
@EugeneKhutoryansky ah. Thank you for explaining it to me
woah!! after so long!!
So this is completely separate from particle "spin" right?
Particle spin in quantum mechanics is completely different. I cover Quantum Spin in my video at ua-cam.com/video/3k5IWlVdMbo/v-deo.html
Can you explain why everything in the universe spins?
From subatomic particles, to galaxies. Always spinning! Nothing in the universe is stationary.
Is there a spin theory like the M theory?
subatomic particles dont spin, they "spin." Everything else in the universe spins because in the early universe when matter amalgamated, the momentum from the compaction was conserved.
The spin of subatomic particles has nothing to do with actually spinning. It's just a name we give it, since there is angular momentum due to bodies having this property.
Thanks again
You are welcome and thanks.
well done
Thanks.
Very great
Thanks.
@@EugeneKhutoryansky а где вы учились, если не секрет?)
University of Illinois at Champaign Urbana
@@EugeneKhutoryansky кто-нибудь поддерживает Ваш проект?
I have a Patreon page at www.patreon.com/EugeneK/about
Hi, Eugene, thanks for some great insights. You have some videos that really helped me a lot understanding some things. But since having seen a lot of other channels I'd suggest getting a bit more modern in some aspects - maybe you get an idea of what I could mean. If interested in details simply ask. What I will never understand why all animations are so FAST. There are things that have to be understood step by step - and they do as if there was no tomorrow. I had to slow down this video to 1/4 of speed in order to watch the arrows grow and shrink and THIINK about what I see.
Unfortunately there are some aspects I simply do not get. For example: Why do the rotating spheres with the spring have momenta that do not change direction most of the time? Why do they rotate only while turning around? Shouldn't they change direction instantly? You answer some interesting aspects but leave open so many questions regarding what you show - is this intended? There habe been some videos in the nearer past where I have noticed this effect of rising more questions than answering...
Have you ever corrected a video? I ask as I have seen a video about theory of relativity which the author claimed in that you, Arvin Ash, Sabine Hossenfelder, PTBS-Space time and many more have been wrong and he had good arguments. Unfortunately at the moment I have no clue who the person is... But of course in the videos here things are covered that are topics of debates and to some extent this should be part of your videos? Don't get me wrong: Of course physikcs is nothing that's debatable by itself - but our knowledge or understanding of it has undergone some changes and this process is going on - so more debate aspects should be included in some videos. Does ANYONE really know what's ging on with space and time? And what to think about the Schwarzschild metric for example which is at it's best some approximation of the real things. How can we, one or you speak about those things as if they were without unknown or unclear aspects? This is wondering me more an more...
Regards!
Why don't you accept islam? Islam is a religion of science.
@@WajihaHaleema-bk8xq I did not talk about relegion in any way. It was pure physics here. I talked about Schwarzschild and Hossenfelder... Both have no direct relation to any religion.
@@volkerjung4804 Study islam. It is the religion of science.
@@volkerjung4804 Whatever it is. Science will not take you to heaven. Its islam that will guarantee you heaven.
You will soon become a muslim.
Angular momentum is constant ONLY if there are no external forces acting on it -- if a motor were to spin the system up to double the angular velocity the angular momentum would NOT remain constant!
It's really no net torques. Angular momentum is still conserved on a system of bodies, freely falling in a uniform gravitational field. It's also conserved if there are external forces, but they add up to zero. Or if there are external forces, but they are so brief that their impulse is insignificant.
@@carultch External forces that sum to zero is exactly the same thing as NO EXTERNAL FORCES AT ALL.
@@Raptorman0909Nope. Not true. You cant have a net torque with no external
forces. You can have a torque if the forces add up to zero.
@@ricomajestic You're playing word salad games. If the forces sum to zero there is no net force. If the torques sum to zero there is no net torque. The angular momentum of a system remains constant so long as no external forces act on it, but if external forces are acting on it resulting in a net torque then the angular momentum will/must change! Those are the rules!
@@Raptorman0909 "External forces that sum to zero is EXACTLY the same thing as NO EXTERNAL FORCES AT ALL." This is what you said initially which is wrong!. A system where there are no external forces is not the same as a system where the forces sum to zero. The net force on an object would be the same but the net torques might be different in those two cases! An object where there are no external forces acting on it cannot have a net torque however an object who's external forces add up to zero can have a net external torque so they are not equivalent statements. What you call "word salad' can actually be critical to the motion of a structure or if you want to prevent it from moving. So you indeed need to worry about correct language in science!
Do you know that conservation and Newton's laws work only in absolute time. In variable time, for example, Newton's 3rd law should be adjusted like that: F1×D1²=-F2×D2², where D is time dilation factors. Read details in "Time Matters, 9th edition".
All of this was explained in quran. 1400 years ago.
I have trouble understanding how a radial force affects a tangential momentum.
Radial momentum becomes tangential momentum 90 degrees later in the rotation.
@@EugeneKhutoryanskyIf the radial force nudges the sphere radially inwards as the sphere rotates there is now a component of the spring force in the direction of motion, which increases the linear speed of the sphere, which in turn increases the angular momentum? Similarly, the spring force has a component opposing the motion when the sphere moves radially outwards?
Centrifugal and centripetal forces in circular motion.
Centrifugal force doesn't exist. It is only there to explain why an object does not fall toward the center from the object's own reference frame, where the linear velocity is zero. It doesn’t exist in all reference frames.
For example, between the sun and the Earth, gravity is the centripetal force for the Earth orbit, and it is the only force.
Sorry, but I think it's you Mysoi, that's slightly mistaken. Gravity is not a force either. The centripetal and centrifugal forces in orbital motion, are both apparent forces, which only appear in an accelerated frame of reference. Any celestial body in space is moving on a geodesic path, or the nearest thing to a straight line in a curved space-time. Which means the net acceleration at it's centre is zero. The point where the centripetal and centrifugal effects cancel.
@@cybermonkeys
I learned the Einstein field equation, differential geometry, and tensor concepts, but in the context of the Earth/Sun, Newton’s model is sufficient. Also, when explaining to someone, we have to know their level of understanding in order to enlighten them.
@@Mysoi123 Yes, and I totally agree, but in Newtonian Mechanics, both the gravitational (centripetal) and centrifugal forces both exist. That is the reason why the Earth and Moon, both orbit around their common centre of mass. Exactly the same for the Earth-Moon system around the Solar System barycentre. It's not as easy as just saying Centrifugal Force does not exist, but I understand where you're coming from. Have a great day my fellow physicist.
@@cybermonkeys That is not true; you cannot say both forces exist. For example, if you're inside floating around in a box, when the box accelerates, you will not move along with the box immediately. Instead, you will move only when the box hits you, and a force acts on you to accelerate you together with the box. From your frame of reference, the box is standing still, >>it is not moving
Wow
Я на Физтехе использую эти видео в своей преподавательской деятельности
Love it❤
Thanks.
love it
4:43 This bit isn't quite making sense to me. You stopped the rotation 90 degrees after the force was applied, then made it look as if the two red arrows pointing in the same direction were somehow significant - but it can't be significant, because when the force was applied, the motion was at 90 degrees to it. I mean, I understand that angular momentum is conserved, I get that - but there seems to be a step missing from the explanation. WHY does a radial force change the linear speed? There's nothing here that explains that clearly.
Radial momentum becomes tangential momentum 90 degrees later in the rotation.
@@EugeneKhutoryansky Hmm... but what about the sphere opposite? Isn't that one slowed down by it?
The issue is whether the extra force is towards or away from the center. It does not matter whether if it is while the ball is on the right or left side.
@@EugeneKhutoryansky Thank you for trying to help me understand, but I'm still confused. The animation appears to show the force applying to the left, and the ball has moved to the top position by the time the arrow is shown. I'm still unable to understand what you're trying to convey with this animation. Somehow a radial force translates to an increase in angular speed: I understand that, but I can't grasp how it's happening, and the fact that the red arrows both point to the left feels like a distraction.
Angular momentum force vector yellow conserved rectangle purple shrink red blue constant force brief extra greater linear force rotating newton yellow teacher ji
So why we need the "principle" of conservation of angular momentum since we can explain these phenomena without it?
It can make the calculations easier.
It is also highly useful to consider whether a given system conserves angular momentum or not. If we know that it does before jumping into calculations, we can save a lot of work.
If we know that it doesn't, we can consider where and why.
@@narfwhals7843 can you give a simple example in which angular momentum is not conserved? because the principle says that angular momentum is always conserved - if there is any (for a specific frame of reference)!
@@orfeaskar3717
Conservation laws usually apply to closed systems.
If we consider a system with an external force, usually conserved quantities may not be conserved.
Say the system is a weather vane by itself. If we consider the wind to be an external force, this will change the angular momentum of our system.
Of course we can include the wind into our system and momentum is again conserved, but knowing what is "internal" and what is "external" is a useful tool for calculations and knowing what we can ignore or what we should have included.
In general, angular momentum is conserved for systems where the physics does not depend on the orientation. (Noether's Theorem).
no gravity present? Are you sure this would be the case?
Read quran and accept islam then you will automatically become knowledgeable.
Are the red forces “imaginary?” In this context of angular momentum? Sorry Im a layman. The spheres just “want” to travel in a linear path and the different imaginary forces depend on how close or far the balls rotate around each other?
Thank you for your videos.
What This channel is telling you. Islam told us 1400 years ago.
My mentor you haven't replied to my previous comment. I am anxiously waiting for your reply.
I just replied.
@@EugeneKhutoryansky Thanls a lot. Stay safe
Noether's Theorem anybody?
Quasar
I like the voice.
Listen to muslim voices. Accept islam.
@@WajihaHaleema-bk8xq why except Islam?
@@pluto9000 Islam is only truth.
@@pluto9000 islam is truth
@@pluto9000 Accept the ttutg
I wonder why is it still valid in general relativity
I cover momentum in Relativity in my video at ua-cam.com/video/fIh7hbhpxzI/v-deo.html
@@EugeneKhutoryansky thanks, but this video doesn't explain the general relativity case for the angular momentum conservation. I guess it's not an easy problem.
All you have to do is double the points again
All this science is a very trivial by product of islam.
Re: the first system to consider -- as soon as you have mass, you have gravity. This is also why special relativity is wrong from the get go. Luckily general relativity wasn't built right on top of special relativity. Wait, what?
Adding gravity to the first system wouldn't change the outcome with regards to the phenomenon I am trying to show.
Special Relativity Is not wrong from the get go. Einstein did not consider acceleration in SR, it was only concerned with the constant motion of objects in a straight line, or Inertial frames of reference, or the principle of inertia.
When he began thinking about acceleration, or non-inertial frames of reference, then he realised that gravity was just the accelerated motion, that only appears in an accelerated frame of reference. Very similar to the appearance of the centrifugal force in Newtonian Mechanics.
@@cybermonkeys Once there is a single atom in a model, there is acceleration & gravity. Without the latter two, the model is wrong and worthless.
@@FloydMaxwell Well, now you're talking about single atoms, which reaches into the realms of Quantum Mechanics, where gravity doesn't play very well with the known equations. Gravity and acceleration aren't two separate things. Gravity is an apparent force that only appears in an accelerated frame of reference. Special Relativity Is not worthless, because it evolved our understanding of Space and Time, which we're not absolute, like Newton had suggested in his Principia.
@@cybermonkeys You haven't a clue what you're talking about
You describe the linear velocity of the spheres changing as the distance from rotational center is changed. This is not true from how I understand it. The velocity stays the same, it's just that the circumference of its path is smaller, so it completes each orbit faster.
That is not correct. The velocity increases. Otherwise, angular momentum would not be conserved, and energy would not be conserved.
@@EugeneKhutoryansky The circumference of a circle is 2(pi)r. Therefore if the radius is cut in half, so will be the circumference. As per your video, the momentum of the sphere can be described by the area of a rectangle with sides (radius) and (velocity). If radius is halved, velocity must double to maintain the area. So you are saying that a sphere traveling in a circle that is then pulled in to now travel in half the radius, will necessarily orbit 4 times faster (twice the velocity around half the distance)? That is not the way I previously thought of it, but I will have to try an experiment. Always good to learn something new.