Gyroscopic Precession
ฝัง
- เผยแพร่เมื่อ 2 มิ.ย. 2024
- NOTE: This video will appear in a playlist on Smarter Every Day hence the references to Veritasium. Destin does lots of cool science stuff - check out his channel if you haven't already / destinws2
We have been collaborating on rotational motion, which is timely for some of the videos I've been doing lately. In this video I talk about gyroscopic precession - the "wobbling" of a spinning top around its axis.
This is caused by the torque due to the object's weight. The big idea is that the torque vector increases angular momentum in the direction of torque. So if there is no angular momentum initially, it will cause the system to swing in such a direction that it is rotating with new angular momentum in the direction of the torque. However, if there was angular momentum to begin with, the torque will change the direction of that angular momentum by causing precession.
I'm going to be honest, you straight up jump scared me there at the end.
yes me too
Ye, i said "you fool!" :)))
fake loud sounds, always do that
He should have added some bloody special effects as if he was decapitated.
wus
that ending scared me XD
Yup 😂
AJ Cary Legitimately made me jump.
AJ Cary holyshit I jumped off my chair.
+AJ Cary (Ajc159 Mario Kart Wii) I was so shocked I pooped my guts out. (not literally)
+AJ Cary (Ajc159 Mario Kart Wii) +1
How humbling is the pursuit of knowledge. I came here after a several week long binge of spinning tops, and it took me that long to formulate the question relating to momentum and procession. I am a retired carpenter and the only math I have ever used is Trigonometry for stairs and rafters.
Coming back to rewatch this years later now that it's my university homework to watch it. I can't believe this was released back in 2012
Can anyone further explain what he is torquing about?
Oh ha. Ha. Ha.
Ask Miley Cyrus? She seems to be an expert torquer.
Guys, this guy is awesome
quit torquing around
TORQUING IS A VECTOR WITH THE UNIT (N*m) OBTAINED BY A VECTORIAL MULTIPLICATION OF POSITION (m) BY A FORCE (F), WHOSE DIRECTION IS GIVEN BY THE RIGHT-HAND RULE.
NOW IN THE CASE OF THE VIDEO'S EXAMPLE, THERE'S 2 TORQUES:
T1=(AXIS POSITION BETWEEN THE WHEEL'S AXIS AND THE ROPE)m X (WEIGHT FORCE ON THE WHEEL CENTER)N=N*m AND ITS DIRECTION IS OVER THE CAMERA.
T2=(AXIS POSITION BETWEEN THE WHEEL CENTER AND ITS CIRCUNFERENCE)m X (COUNTERCLOCKWISE APPLIED FORCE ON THE CIRCUNFERENCE)F=N*m AND ITS DIRECTION IS PERPENDICULAR TO T1
IF WE MAKE T1 + T2 VECTORIALLY WITH PYTHAGORAS (CZ BOTH ARE PERPEDICULAR ) IT SHOWS A VECTOR THAT MAKE IT ROTATE WITHOUT FALL DOWN (WITHOUT FRICTION)
I was stuck with the gyroscopic couple for a day or two, every time I thought I have understood, I would again get confused.
But your physical approach made things a lot more transparent to me.
Thank you very much, sir.
Did you really understand or are you just able to apply the right-hand-rule now?
Damn, this video doesn't seem 10 years old at all! Your quality is fantastic nowadays but man, you had it on a next level back then too!
2012 is not that long ago, right? RIGHT?! >.
@@sandercohen5543 It's definitely as long as someone's age :D
@@TamimProduction jesus ?
@@PluetoeInc.WADATFFF
This video is probably the best and simplest way to explain Gyroscopic effect on TH-cam. Good work.
The bit at the end made me jump.
Yeah did the same to me, man. That's what I get for being half awake.
Love it when you find out you're not the only one XD
Hahaha yeah man!!
dude same
don't drop a samsung galaxy s4 on your face when someone is hitten by a spinning wheel.
it hurts
At 1:21 you say that torque is given by: T=F x r, but isn't it T= r x F?? The order matters when it comes to cross product.
You are indeed correct, but this is fixed in an annotation.
rxf equals to minus of fxr
@@vishalmali921actually it is radius VECTOR and not the magnitude, with direction from centre to edge.
You are right, but he used the right hand rule in special way that he get a correct direction
True that
The way you explain things is amazing. Schools around the world should have teachers like you!
Thanks for the vid. Great work as always!
Male teachers get metoo'd so that's why there's only incompetent female teachers in the education system now.
And here, you are approaching 10 million. And your this video is benefitting still 10th generation of STEM child.
The torque vector as described would actually be R cross F, not F cross R. Don't forget this on your exams or you will definitely get the wrong answer!!!
You'd just get the answer in the opposite direction. Going any further, yes you would be completely wrong.
But the rule of thumb is, stretch the fingers across the radius, then curl your finger in the direction of the force.
If they get this concept it should fall together.
he did not say that it was the cross product. He simply said "F times r",which means he did not imply to say that the cross product is F x r
@@pallavi6013 Then why did he change it and thank me for pointing it out.
@@pallavi6013Elementary school students don't watch this video so it's kinda implied that he meant cross product
If you are more used to using force, mass and velocity, you can integrate the weel as connected rotating masses having the rotational force distributed among them, then you'll see that the masses along the weel will follow curved paths according to the rotating directions
Great video. I've been watching this video for the past 8 years !!! The arrow's vectors were amazing to view the actual thing. Thanks Derek. As with everything you do, it's always very well made and full of love and details !! 🏆
Very nice and informative video. There is a small typo at t=1.14. The torque is not F cross r, but r cross F.
Omg the end made me jump! lol.
I jumped too xD
I almost died. Headphones up too loud.
I saw that coming a mile away
Wow this was great. Nice, clear explanation with a perfect visual representation of the vectors. This is exactly what I needed.
I watched a bunch of videos and checked this concept out in few books too but nothing made sense as much as Derek's video did. World's blessed to have a youtuber like him😊😊
You cleared my concept in just 8min(actually i had to watch it twice) what i was trying to understand from last one hour.
Thank you.
I love science, especially when it is fun (near the end of this video). :D
Man physics is truly amazing, really one of the most amazing subjects out there
Thanks for your explanation, Veritasium!
His name is Derek, he said it right at the start of the video.
mangovid!
Okay, I know this is an "old" video, but I'd really like to see what happens when you have two wheels spinning in opposite directions on the same axle.
their torks would cancel and the whole thing falls down. BUT the wheel that is farther away from the rope has a bigger distance so its angular momentum will count higher towards the total tork
@@botfred743 yessir youre right
Annuls the forces. You see that at the end of the bicycle vid
That depends on which side of the rope they're on. If they're on opposite sides, it will rotate around the vertical axis faster, right?
Okay, I know this is an "old" comment, but I'd really like to say that when there are two wheels at equal distances from the center of the axle the torques due to gravitational force cancel out each other and the wheels keep spinning how the are. But it will be interesting if the wheels are imbalanced, say different distances from the center of the axle or different masses. I think that also will be some kind of weird and mathematically complicated gyroscopic motion
You explained this more clearly than my physics professor... thank you :)
You blew my sh**t off at the end!!!
If you have a door, you excert a force(like a short impulse) where the door knob is... the door starts moving ''rotating'' , and that ONGOING movement is the angular momentum, and the torque is responsible for it
Amazing! Thanks! I am a PPL(A) student pilot and this video makes understanding gyroscopic precession easy!
My first real experience with Gyroscopic Precession was in class in the Air Force for Inertial Nav. The Stable Platform held three gyros in three different axises. The platform failed to spin up, to our Instructor had three of us wait five minutes, he'd go get a replacement and we'd move it to the floor. We waited the five minutes, not quite enough, it was still spinning enough that we couldn't control it enough to even come close to getting it on the floor where he wanted it, we had to lean how go guide it and we put it about ten feet away! In practice, out in the field you wait thirty minutes before moving it. Especially out of the front Cockpit of an F-4 Phantom.
Veritasium Actually, Torque=r X F and not F X r. This will change the torque's direction.
***** they're the same thing.
John Mcleavy Torque is a vector and therefore r X F has the opposite direction to that of F X r although their magnitude will be same.
Alwin Priven Vector product is not commutative.
Cross product of vectors is not commutative; dot product is commutative.
+Alwin Priven it's about that hand movement he did to find the direction. To figure the direction out for any cross product you point your fingers in the direction of the vector before the 'X' and then curl them towards the direction of the vector behind the 'X'. If you try it out you'll see that if you reverse the order that you take the cross product of the vectors the product will point in the opposite direction :)
Hey Derek! that was so cool how you broke down the concept into simple easy to understand force vectors. Gyroscopic Precession with the bicycle wheel was something I really struggled to understand in physics class. Just wanted to say I figured out a way to explain the same concept and do the same demo with a fidget spinner on my channel so if you want to learn a little more, feel free to check it out :)
Hey that sounds cool! But I can't find it...
That's extremely clear and logical for me, make perfect sense! Thank you for dedicate yourself to doing all of the awesome stuff in your channel and applying science in to real world! You are my idol seriously!
As far as I have read, torque is not force cross radius, it is radius cross force. This cross product thing changes the direction completely so He always told us to be careful
Learning this for my Mechanical Design! Thanks for the input, Derek!
I've always wondered if you used 2 spinning cones to form a hollow wall and pumped water from the narrow end to the wide end, and back again.
Would the engy of pumping translate to a force. Sideways or down?
Watched videos from this channel for entertainment and interest when I was a kid.... Now watching them to clear doubts for my upcoming exams... Studying aerospace engineering (mechanical)
This is legitimately the best veritasium video ever.
Thank you! Much clearer explanation than my physics professor's!
ahahaha :D 5 likes = 5 "happy edu system competitors"
3:44 We need that sound in a game when player dies
Nice video! I was looking for a video explaining the physics behind Ultimate Frisbee throws for a school project. This helped me but I also realized that there aren't any videos scientifically explaining a Frisbee throw. I think you'd be the best option for posting a video on that topic. What's more, most people have thrown a disc at some point in their life. Therefore, people could easily relate to more complex concepts like gyroscopic precession as it's visible in a frisbee throw.
I've loved this channel for a long time but had no use for the information in everyday life (other than going out to apply it). I'm now training to be a pilot and my book didn't have the greatest explanation of this. This example was crystal clear. Thanks!!!
Try not to wait 25 years to discover what this lady realised
th-cam.com/video/sVX0FvTNtbw/w-d-xo.html
The force is an energy field created by all living things. It surrounds us. It penetrates us. It binds the galaxy together.
Mmmm. Correct you are.
He said the force a lot so I felt compelled.
it penetrates us?
Oscar V LMAO It's ok. It buys dinner first.
Duct tape works also
Another great physics video from the University of TH-cam.
Thanks.
you commented this 6 years ago but I'm your second liker, it's an honor.
1:03 - 0:55
There is an example we can do about the rotation of objects where the force trying to rotate the wheel increases the energy stored in the acceleration of an object in the direction of this force
I love smartereveryday. Destins enthusiasm and hunger for knowledge is what drives me to his videos. It's kind of the same for you. Guess I see your channel as kind of Destins younger brother channel. Hope you don't take that as a provocation, because to me it's beautiful science and knowledge!
It took me about 2 years to actually get this. Vectors can be confusing.
+Sangwoo ‘KeimaFool’ Shin Exactly, this confused me so long 2 years ago.
+Sangwoo “KeimaFool” Shin that means one year to go for me.
I am in fourth grade and I think this kinda hard
I watched this 2 years ago and I still don't understand... Do you happen to have any resources on this topic online?
All you need to understand this is how vectors add. It really isn't that complicated.
Also, torque is the change in angular momentum, and angular momentum is (in this particular case, not true for every solid) is a vector that points perpendicular to how the object spins.
I jumped at the end, haha.
Never understood this phenomenon properly until I watched this video. Thanks😁
Thank you for creating this video, it helped my understanding of the forces involved in the precession of spinning objects. I found your video while looking for a video of someone who has connected two bicycle wheels on one axis, spun them in opposite directions to verify that the angular momentum vectors of each wheel cancel with one another resulting in the absence of the gyroscopic motion. If you are so inclined, I would like to see you do the experiment or link me to a video where the experiment has already been done.
Hi, I would like to know if you had two wheels, counter balancing each other and both spinning in a counter clockwise motion from the center point as the one in your video is doing, would they possibly create less tension on the suspending rope? If force were also applied to the orbits making them spin in a counter clockwise motion (top down) as this one is, would that possibly create a small amount of lift?
+RonALampman No, the force on the rope remains the same. If you have contra-rotating wheels, the angular momenta cancel out, and the thing just flops over like normal (except in the case you describe, where it sounds like the weights are balanced, so it could easily stay upright). But there is no antigravity going on here, the tension on the rope equals the weight of the wheel, always.
+TheHue's SciTech The reason I ask is because I know when a bullet is shot at a wall or hard ceiling at a low angle from the wall or ceiling, it will follow that surface (wall or ceiling). For instance, if in a concrete tunnel and firing a round angled slightly up from vertical and near the ceiling, when it ricochets off the ceiling, it will continue to curve toward the ceiling until it looses enough velocity to overcome it's weight. The same holds true for throwing a light, air filled ball. When spinning backward from the direction it was thrown, it will rise. I've done this with small beach balls many times.
RonALampman Oh sure, aerodynamic effects (like backspin & lift) are real things for sure. Normally not considered in problems like this, though! And unfortunately, drag always comes along and spoils the party.
+TheHue's SciTech LOL True! But I still intend to do an experiment with this concept when I get my shop finished and 3D printer setup.
Then the sum of the torques is zero and angular momentum is conserved i.e., the wheels will not tilt, but keep spinning until friction/drag brings it to a stop.
3:28 hey vsauce
Thank you, Veritasium. I legit understood it.
I have watched many videos but this explains a lot about the gyroscopes. Thank you
It sounded like he was saying Twerk. Maybe thats where the term came from. Twerking is really just Torquing.
+Anthony O'Toole *Inception horn*
+Anthony O'Toole I think twerking needs its own distinct physical analysis, somewhere in the field of oscillatory motion and forces of attraction.
+Anthony O'Toole The little top from inception
+Akuma Tokkou still force at a pivot distance
really funny!!!!
What I don't understand is at 3:48, i.e., "There's a torque pointing out this way (short purple arrow)" I don't believe that he had introduced or explained this torque. Not to my understanding, anyway.
It is nice to see how Force and torque play nicely with the rules of vector
My AP Physics professor showed us an experiment like this, but his bicycle wheel was filled with cement, so it had more mass (momentum? inertia?). He had us hold it, while on a swivel chair, and sped it up with a drill. We could steer the direction of the chair by tilting the wheel. I didn't understand the maths of it at the time.
(I know this is 7 years late, but I just discovered this channel.)
I wanted to see that specific helicopter video by Destin by following the link shown on this video. Disappointingly I ended up on his youtube homepage instead. With hundreds of videos to browse through I soon gave up. Hate it when that happens.
i can help with that.. watch?v=Cg1CPmtZL4c&list=PL6CECC2E56B68A2C3
hahahah nice ending it got me
Dude this changing of thumnails is really working, im rewatching a LOT of old videos
Hi, just saw the coast guard videos and came here. 11yrs after 😂. Thank you for the series
Gyroscopic procession is where an induced gravity field is rotated out of phase with the atom core center of the planet.
Haha the ending was so silly it made me laugh
The best explain that I have already seen! Congratulations for your didactically!
Thank you so much. The lecture vids my prof assigned made absolutely no sense because they don't teach visually like this. It makes complete sense now
At 2:59......why does the "torque pushing THAT WAY swing the other Angular Momentum vector THIS WAY"? We can see that happening quite clearly in the video, but please explain WHY that happens?.
What would happen if I spun that wheel in the opposite direction...the wheel would now precess in the opposite direction, correct? So clearly the direction of precession has something to do with the direction of the angular momentum of the spinning wheel.
We can see from your video that the effect of precession is always to try and align the axis of the angular momentum of the wheel with the axis of torque caused by gravity. Since we are balancing the wheel only on one point, as the axis of angular momentum of the spinning wheel starts to align with torque, the wheel turns and as a result the direction of the gravitational torque also rotates about the vertical. This goes on and on and the wheel then turns and keeps turning like the way it does.
But my question is not WHAT happens, but WHY does this happen. thanks.
+aswan korula then then r cross F drxn wud change so the wheel will now spin in the opposite drxn while mg cross r is still in same drxn obviously.. so now the resultant vector will be supporting opposite motion of the wheel
yes, but why? why does the angular momentum vector try to align with the gravity torque. I understand that it does this, but my question is why?
+aswan korula Torque is an analog for force. while a net force is a change in linear momentum over a time interval, the same is true for torque and angular momentum. So if there's a net torque that implies the angular momentum is changing. In this situation the direction is changing. Somebody correct where I'm going wrong here, I'm pretty new to this topic
Okay but why does the torque move that certain way? That first equation didn't talk about how much force is also being applied upward since it's a wheel. It is then defying gravity, right? The downward spin pulls toward earth/gravity source but the upward spin pushes towards the sky.
I have a bias against equations because they're not language-friendly, but I think there's some mistake or something missing from this explanation. I get that the spin creates a rotation, but I still feel as if there's no proper understanding as to why it's not bouncing around everywhere. Does the downward and upward pull just... cancel each other out?
The torque from the wheel spinning on its axle creates the torque (the red arrow) that keeps it up, since that torque wants to keep traveling away from the axle longitudinally. Then torque from gravity pulling the entire wheel downwards create the 2nd, and separate, torque, which is the one that's causing the entire wheel to rotate around the rope.
At least that's my understanding of it. I'd be glad if someone can verify this.
As in, there're two entirely separate torques in play here:
1st torque: the one created by the wheel spinning on its axle, indicated by the red arrow;
and
2nd torque: the one created by gravity trying to "swing" the entire wheel assembly downward, which is now translated into pushing the entire assembly sideways.
The 2nd torque only pushes instead pulls down because of the 1st torque trying to pull away in the direction of the red arrow, thus keeping the entire assembly relatively perpendicular to the ground, until that torque slowly dies down due to the wheel spinning more and more slowly, caused by the friction between it and the axle.
Ah alright, I get it now, thanks.
So, is there a third upward torque from the resulting rotation around the rope, or does the concept of torque not apply because there's no mass on the other side of the ... fulcrum?
More mechanical physics videos please. You make more sense then my instructor!
If you don't understand this explanation, think of it like this:
Any one point on the edge of the wheel has momentum in it's current direction, ok? Let's say it has the momentum value of 100.
Now imagine pushing that point towards the rope, that is, perpendicular to the direction the wheel is spinning.
Push with a force of 1.
Now, the point has a momentum 100 in one direction and 1 in another.
Add these together and you get a momentum of 100 + x in a slightly tilted direction.
The path that the point will now take to go around the wheel will now be inclined from the original path. Read that until you get it.
The point at which the point will be farthest from the original point's trajectory is roughly 90 degrees from where the force was applied.
Therefore, the force will push up at 90 degrees and you get gyroscopic precession.
cool
Nani
Lmao
Channel name : "How To Make Sushi"
*clicks on channel*
recent videos : "Burnt Basque Cheese Cake"
@@kennarajora6532 Hahah
As I understand, the direction of the angular momentum vector was chosen arbitrarily. In other words, we could have made it the left hand rule. It is just a way to describe rotation easily. I feel like this description is trying to say this phenomenon is caused by outward angular momentum, but that's just a concept we invented.
To understand the real reason you can think of the top of the wheel as a point. With no spinning, that point will travel outward, pivoting around the string vertically. But this point is moving around the wheel, so the side of the wheel that the top rotates towards gets pushed out. In the same way, the bottom of the wheel is trying to travel inwards, so the other side of the wheel gets pushed inward. So if you think about it, it's just like applying an outward force to the left of the wheel, and an inward force to the right of the wheel, or vise versa. That's what causes the horizontal rotation instead of the vertical rotation.
thanks a ton for this visualisation, it was EXACTLY what i needed to understand it!!
@Veritasium, if I'm not mistaken this example is a bit like a helicopter, the spinning wheel is the main rotor and the rope is like the tail with the small rotor providing an opposite force or "thrust" so that the helicopter doesn't itself spin wildly opposite the direction of the main rotor. And by manipulating the torque angle of the blades which the "angular momentum" follows, the direction of the helicopter is altered.
I watched this video 3 years ago back in high school and am now watching it again as an engineering major for completely different reasons
You can eat a gyro, but you can't eat a gyro.
If you eat a gyro, you might have to sleep standing up.
Good one Dr Jim!
William Ross Docktor. I build marinas. Boat docks. I am not a doctor.
Docktor Jim Ah, another good pun.
That ending damn ... I was wearing headphones at its highest volume ... :^)
My headphones barely survived the ridiculously obnoxious noise at the beginning. Kept watching because I had time to do it and because I was hoping to find some stuff about a spinning globe... Low volume, because I was afraid there might be more of that.
Thank you, that was a very crisp explanation without any fluff.
Very clear audio, way better than our recorded lectures here at the University of Illinois.
hi to all the student pilots who are watching this :)
+Mayank Kashyap LOL - Yup, read about it but wanted a video to help me understand the left turning tendency due to this phenomenon...I still don't fully understand it, so for now, I'll keep on using right rudder on take offs and will keep on learning :-)
+Hector Torres hahaha 😀😀 happy landings brother.
ATPL lifeeee... lol
Lol just started flight school. I just wanted to grese some landings, not learn about gyroscopic presecion.
@@13htorrespr Leaving this comment for future confused student pilots - left turning tendency is due to a few different phenomena, but there are 2 main ones that your flight school will want you to know. The first is that a propeller is really 2 sets of wings, which are spun in order to produce forwards lift and pull the plane forward. The downwards spinning blade actually produces slightly more lift than the upwards blade does, and as such will pull the plane to the left. Some airplanes have propellers that spin the other way, and those aircraft actually exhibit a right turning tendency!. The second phenomenon is due to the propeller slipstream. This is often over-complicated in ground school, but it's really easy to understand once you can visualize it. Air that comes through the propeller leaves in a spiral motion (due to the aerodynamic effects of a spinning propeller) and this spiral surrounds the aircraft. This spiral hits the side of the rudder, thereby pushing the plane to the left.
From my standpoint as a physics student, this explanation is not accurate :/
The right-hand rule for vectors associated with rotation is simply a convention. The convention could just as easily have been a "left hand rule", and with the logic presented in this video, the explanation is no longer consistent (with the logic presented in this video, a left-hand rule would have resulted in the bicycle wheel precessing in the other direction).
From my understanding, angular momenta are conceptual one-directional axes that exist in three dimensional space. They do not originate from points in space and go outward from those points; they are axes. With this understanding, the explanation present in this video is incorrect.
I appreciate the correction made at 1:11. Angular momentum is a "cross product", and the order of the "multiplication" does indeed matter.
Actually, if we adopted a left hand rule, it would still work.
Felipe A. Barretto explain? I tried using a left hand rule and it doesn't work, but I'd like to see your interpretation c:
Josh D. Try using it in both the angular momentum and the torque.
1D axes are the same as having something come from a point.
Dilip Tien Axes do not originate from any point. They are lines.
This was mind blowing. Very easy to understand! Thank you
Amazing stuff. And thanks to TH-cam I can play bits and pieces 20 times until I get it.
I have a question, how would same wheel react in space or zero G?
Ignore the effect of gravity in this case that's it.
Kanan Anand so it will rotate like a spinning disk in 1 axis? or will it have 2 axis rotation?
***** I think it will have only one axis of rotation. Since fixing it with the rope wouldn't do anything in zero gravity.
There would be no Gyroscopic precession. Consider this: The center of mass of the wheel is on the center, which is pulled down by gravity when the wheel is held perpendicular to ground, and thus on being released, it eventually aligns itself parallel to ground in a rotatory motion with torque produced by the interaction of gravitational force and radius equal to the distance of the center from the pivot point (T=r x F). The direction of this torque is along the radius of the wheel outwards which is causing the wheel to move in the direction radially outward. But here there is angular momentum acting outward, perpendicular to the wheel. Thus the precession is in the direction of the resultant vector.
In simple terms, the force which is necessary for this precession is GRAVITY and in absence of it there cannot be any precession.
nisnature But if you gave it a slight nudge it would precess. Or would the correct word be nutate? I'm never sure.
what is this witchcraft?!?!
he is using the Force
neuron1618
Imagine if he would go to the dark side, he would be unstoppable!
Angelous922 i think you mean the torque side...
i have no friends...
Lool
Arre you muggle?
Pretty sure I was able to imagine this in my head decades before learning it is true. Thanks for reminding me!
So throughout this entire playlist (Smarter Everyday DEEP DIVE #1 - Helicopter Physics!) I've been slowly learning more and more about gyroscopic procession and angular momentum, and my mind of course has constantly been asking the question, "How?" and with each and every new revelation, "How?" and "Why?" I remember my technology teacher in highschool who was teaching us what we needed to earn CompTIA certifications telling us that we shouldn't have our CD/DVD drives sitting sideways because it would stress the drive more over time and reduce its lifespan. I thought then that she had to be wrong because theoretically a solid disc has equal mass on all sides, right? I realize now I was wrong, but I think I've also realized something else. So I have a hypothesis on this, and that is that the acceleration of gravity is affecting the wheel at all times, and so when it's not spinning it simply falls. I hope I can explain this next part clearly: So again the wheel has a mass and the acceleration of gravity is affecting that mass at all times, but acceleration is applied over time. So if you imagine one point on the wheel and imagine it's mass that's spinning at X rpm's it will still have had the force of gravity applied to it over time, but the vector of the force of gravity will change because of the wheel's spin. At different points in time it will either be working with or fighting against the acceleration of gravity. That's about as much as I've got and again it's a hypothesis. But still very cool stuff.
Does this explain why you are able to balance on a bicycle even though it should fall over since it doesn't have enough wheels to stay up on its own (like a car)?
No. A lot of people claim that gyroscopic effects keep a bike up, and a lot of others claim that front wheel rake distance is what does it. But scientists have built bikes with contra-rotating wheels and negative rake distances, and human riders can still ride them just fine. It turns out the control systems in our brain are all that's required!
Having said that, a riderless bike can stay upright if it has a positive rake distance, whereas it can't with a negative rake. So absolutely, all these effects are useful to some extent. But it really is primarily your brain that keeps the bike upright.
nice response m8! you explained it pretty darn well.
I dont get how there is a torque to 1 side. the wheel is symmetrical. can someone give me a good explanation? what would have happened if he spun the wheel the other way
The best visualization for me was the smarter everyday helicopter video....
The very short and therefore incomplete answer is that gravity is pulling the wheel _down_ on the side that has no string attached. When any spinning mass is turned or tilted in a direction _other than_ the one it is spinning, the way the mass moves is thrown out of whack (technical terms here. Don't worry, I'm a scientitian!). That makes the wheel push itself in weird (put actually quite predictable) directions, which gives the above results. It's a bit (meaning not at all, but it might help to think of it as) like if your car goes north, then turns west too abruptly and flips. You might think "hey, I'm driving forwards, so I should flip over forwards", but the way that momentum is affecting your car, turning before flipping makes you flip sideways. This is kinda (*cough* dangerously oversimplified *cough*) the same, but with rotational forces instead of the direction force of your car going north.
Did that make any sense? Because I think my brain went on vacation in protest about three lines in....
Robert Roman no i mean how does the wheel get pulled to one side when its symmetrical. what decide the side it moves?
rgqwerty63
What decides the side it moves to is which way you tilt the wheel. In the video, it was tied with a string on one side, so the other side of it started getting pulled down, and it spun in the resulting direction. Had the string been on the other side (or had he spun the wheel in the other direction), it would end up going the other way.
_Note:_ I edited this because Robert made a good argument below. After editing, I found that the argument might not be so good after all, so I am conflicted. Please read the continued comments to see if I can be trusted.... Dun dun duuuuuun!
Henrik Larsen thank you that makes sense.what confused me is that he used a right hand rule, meaning had he spun it the other way, it wouldnt have worked
3:00 오른손법칙에 따른 자이로모멘트 방향의 계산
1. 바퀴의 자전방향 회전벡터: 검지(두번째 손가락)
2. 자중에 의해 바퀴에 가해지는 회전벡터: 중지(세번째 손가락)
3. 각운동량 보존에 의해 발생되는 자이로모멘트 회전벡터: 엄지(첫번째 손가락)
3:04 정지화면에서 중지가 내 몸, 검지가 왼쪽, 엄지가 하늘방향을 가르키게 됨
Thank u sir, right now i m studying the gyroscope, and get confused about their direction, but ur video helped me to get out of this confusion
When he explains the rule of the thumb, he says the torque is in the direction of the thumb (along the axis of the wheel). But later on, when he's about to spin the wheel, he now says that the torque is parallel to the wheel. What is now along the axis of the wheel (the former torque) is now angular momentum. I don't get it.
The vector torque is in the direction of his thumb and so is the angular momentum, since linear momentum is in the same direction as force, all of this vectors are from the wheel. But you also have another torque when you let the wheel fall down. When it's spinning, the angular momentum along the axis of the wheel prevents it from falling promptly, but doesn't cancels gravity, then, as the center of mass of the wheel isn't at the point it is connected with the rope, when it falls, you also have position vector pointing to the points of the path of the center of mass, and a force (gravity) tangent to the path, so you have a torque perpendicular to both vectors. That's what "makes the spinning wheel spin"...
You are confused because there are two torques. One is continuous, being generated by the weight of the wheel, and the second occurred only during the pushing that gave the wheel angular momentum.
Christiano Pereira your reply helped me to catch the thing. 😊
That last bump made me jump
Wooow I’ve never seen this before. Really cool. Great explanation and demonstration!!
this is one of the videos of all time
What would happen if you had two gyros spinning in opposite directions?
They would collide and because of that they would stop spinning...
Collide on the same axis ?
Oh you meant it like that. Depending on how much rpm you put on them. If you put equal amount of rpm to both wheels then the axis would stay vertical and the wheels would keep on spinning there.
Ever wonder why some helicopters with higher powers have dual propellers flying in opposite directions?
Probably the cancel out the angular momentum, making it easier for the pilot to NOT consider that the flight object will not lean towards that direction.
Apparently giving the British pilots newer, faster, and stronger planes caused them to lose control as they forgot that it required much more force to steer the plane, ultimately leading to their demise.
This is probably why we went the turbine route, to minimize the torque and angular momentum caused by the wind flux, etc. etc.
cpK054L some helicopters, like coaxial or tandem rotors have dual blades spinning in opposite directions to basically in simple terms "cancel out" torque
Hello to my fellow flight instructors looking for a video that explains precession much better than the mess you just force fed your students!
I'm not a flight instructor, but am in the same boat
Thanks for finally recommending me this TH-cam😭
Thank you for posting this video. Now I understand what my physics book is trying to tell me about precession.
Now I'm not even sure Wat torque is!
This video confused me even more earlier
Torque to a rotating force :)
Hi there, first Of all contrata on The chanell!!! I love it!!!I'm a Airbus captain and I also fly helicopters and I always had a question about precession that nobody that I know can answer me...What is the speed that a disc must be turning to begin having the gyroscopic precession?!?
42 everyone knows that
Thanks a lot Claudius!!!
but 42 what?!?
(it's a joke)((or maybe i'm just stupid and you double joked me))
Physics work at every speed, it's just that the forces may be too small to have an observable effect on the disc if the speed is low. The answer would be then: any speed, you just may not be able to see it.
simple.wikipedia.org/wiki/42_(answer)
Thanks Marek... thanks a lot!!!
I always thought that some force is acting on the wheel in the upward direction due to spinning which balances the gravitational force and restricts the wheel from swinging downwards.
You made it really very clear that the angular momentum due to the affect of gravity on the wheel is being used up to move the wheel forward. And due to the conservation of momentum the wheel is not swinging downwards along the string because all the momentum is being used up to move the wheel forward (Actually backward i.e against the direction of the spin).
That was a great demonstration. The rotation on the rope was opposite what I expected. If you spun it faster, would the axle remain more horizontal? If the bearings were perfect, would the axle maintain its angle for extended time if the wheel held its speed? or would it be necessary not to let spin on the rope for the axle to maintain angle? Does the spinning on the rope eventually allow the axle to go to the vertical? Would forcing it to twist the rope the opposite direction make the axle go beyond horizontal wheel on top?