What Animation vs Physics Got Wrong.
Вставка
- Опубліковано 12 гру 2023
- Animation vs. Physics by Alan Becker is truly a masterpiece. However, I think some of the scene is inacurate. Especially about conservation of momentum and magnetic slingshot.
Please feel free to correct me if I'm wrong. I really like Animation vs Physics, but I found this part is a bit confuse me, so I make this video in hope that someone can help me to clarify that.
All credits to Alan Becker.
Original video: • Animation vs. Physics
Music: Animation vs. Math • Animation vs. Math
Actually, the first one is possible, but it's still partially inaccurate. it's important to clarify that the first one is not using linear momentum to push himself forward, he's using angular momentum from the spinning pendulum and converting it into linear momentum. The reason it's possible is because the surface is not frictionless, you can see the friction coefficient at 1:58 in the original video, it's 0.1 (about the same as someone on ice) so TSC could have in fact built up momentum because exerting the force backward on himself would push off the ground slightly, meaning there are some external forces.
no, you're wrong
@@hunter-km1tn and you're gonna explain why right?
@@hunter-km1tn ah shucks, got me there
@@_TheDoctor OK, there is miser effect. Not more as on video
@@hunter-km1tn damn you really dismantled his argument right there
If they're permanent magnets, they can't form a coil, since current has to flow in a particular direction to polarize a field
could you elaborate? Do you mean the ring magnet or the coil TSC created?
AFAIK, permanent magnet solenoid can work. But it permanently polarized and can also only attracted the magnet so latch made with it must have physical mechanism to move the polar of the magnet.
Yes also if the permanent ring magnets get too close to each other then their magnetic pulls will combine together, And considering the magnets proximity to each other that we see that would be the case! I just wanted to point that one out for you. 😮😮😮😅😅😅
Also the mass of the ring is super high compared to the rocket, and by enough velocity. I think it's possible.
When he made the coil I thought he was going to get electrocuted 😂
I love it how unsure you are about the points you are making
cuz the point actually seem valid. It just really humbles you because now you dont seem like an arrogant dude who knows everything better but rather like someone who accepts different views and just wants to clear things up and show his perspective
That can also come off as a lack of confidence in sometimes.
If he doesn’t fully know what he’s talking about, his points are not as credible. But I do think they make sense nonetheless.
I’d just rather hear from someone who knows what he’s talking about versus someone who doesn’t completely. I wouldn’t want anyone to practice sounding not confident thinking it makes the seem humble.
And this isn’t English lit. Perspectives don’t matter in this case it’s either the wrong or right answer. He’s humble beacuse he may not know the right answer more than wanting other perspectives
dunning kruger effect proves this guy is really smart
It's really impressive that with all of the physics covered in the video, these are the only two points where there is any huge inaccuracy. Like you said, it's truly a masterpiece.
@@armandaneshjoo I mean, once TSC reaches the black hole, the real physics stop and it's just a nice presentation of theoretical concepts instead from then on.
@@armandaneshjoo "Black holes rotate so fast that the initial matter forming them reaches the speed of light" Genuine question, but isn't it literally impossible for any mass to reach the speed of light? Since the lorentz factor simply starts going up
@@armandaneshjoo ...But it still ain't going at light speed, photons which are massless can orbit a black hole too and form a photon sphere since that's where the gravity of the black holes equals c, however mass that were to go straight into the black hole would never actually reach c.
@@armandaneshjoo no? Time only seems to slow down from an outside frame of reference, for the matter inside time is going on just as usual, and we can't see what is beyond because at that point not even photons moving at c can escape
There is a few others, like how orange gets to a geostationary rocket by propelling itself straight up, this is not how we get stuff in orbit : you need to get horizontal velocity, not vertical velocity. There is also a time when orange jumps to get the magnet, while the rocket is still firing, but somehow orange stays at the same level as the rocket. The field of view near the event horizon of the black hole is also wrong.
Also note that when TSC is about to grab the long rope later in the video, he launches himself a bit from the big ball. This pushes him towards the rope but it doesn't move the ball. But because they're in a frictionless surface the ball should have moved backwards a bit.
It's not frictionless, you can see the friction coefficient is 0.1 in the video. Small, but not nothing
@@YoReid Though TSC wasn't able to move at all while trying to walk. That would suggest a much smaller friction coefficient.
But I guess it's not exactly shown what the weight of TSC and the big ball are.
@@nadie887 I think their weights were shown, but have you considered the friction of TSC's feet?
@@9nikolai Right, maybe his feet had less friction than the ball.
@@9nikolaiTSC has smooth feet confirmed
#1) The character stays still since there's friction when throwing the ball, but when the ball is at the end of the rope the friction seems to disappear. I think it's less about conservation of momentum and more that friction is inconsistent during the whole ice section (like how the potential and kinetic energy part only works with mu = 0 since otherwise it would be path-dependent).
#2) I definitely think you're right about the magnets. Unless the rocket's magnetic field somehow swapped polarization during the time it goes through the coil, it should harmonically oscillate until the energy is lost by electromagnetic radiation.
1) i think it could be static to dynamic friction
Let's assume he's in space with no friction, can he move forward with angular momentum ?
@@shrin210 Very much cannot. He could throw the ball and not catch it, meaning he'd have a velocity. That angular momentum trick would only spin him around lol
About the #2, I'm pretty sure the rocket's magnetic field does not swap at any moment, since that would still need the magnets' polarizations to be reverse from one to the next one, but you can cleary see it is not at 3:10 (the red "side" is always on the right of the magnets, never swapped onto the left)
#1 friction is irrelevant i think, if you are inn empty space and spin a 50 kg ball to an angular momentum of 10 m/s
you weighing 100 kg, what would happen if you let go off the rope and let it travel 10 m
then grab the rope again, what would happen?
remember we are not throwing the ball, we are letting go if it wile it has angular momentum.
I am a physics student, and I also noticed these mistakes and got very frustrated about the fact that no one reacted to this. Thank you for covering it !
Well i am pretty sure the first one is correct, since he is spinning the ball.
@@21preend42why did he stop after throwing the ball first time when there is no opposition force like friction? But then he keeps on moving.
Perhaps i missed when he mentioned that there's very little friction there?
Not in english, but i have seen a reaction that truly breakdown the physics and notice the same mistake.
@@spenzr6920 ofc there is little friction there, it's gravity pulling down on you.
@@spenzr6920 I think at some point when he's on the ice, we can see a mu=0.1 pop up, so at least for this small section, there's an external force in play. The friction of the surface does seem pretty inconsistent though because he's still on ice when he sends the ball rolling, and it has no losses on the slope (observed by the ball returning to the same height). I'm going to chalk the inconsistencies down to artistic freedom
alan becker said blame his physics nerd lead animator lol
lol 😂
Under rated comment
I would like to thank you for making this video. I noticed the first mistake as soon as the video was released but I couldn't find anyone else covering it. It's also very fun to read the comments and see other people's perspectives on it.
Edit 1: Many people have provided great explanations on how the first case is true and thanks for that! When I watched the video I just assumed the coefficient of friction to be 0.
Edit 2: Looks like the magnet one MIGHT be correct as well. Truly a well-made physics video by Alan and his team!
Edit 3: The magnet one is NOT true because it violates the law of mechanical energy conservation.
I am disappointed that I only noticed the magnets one
@@ConnorAustin I think that's equally as impressive!
@@ConnorAustinbe glad you noticed any, I just took physics 2 this semester and didn’t even try to notice flaws, was simply enjoying the cool animations 😂
@@AmmoBops me too
i do not think the magnet one is completely wrong...initial speed was say V1 and enters a magnetic field( that is when rocket is near the ring) it covers distance 'x' in time T1 where x is distance from where rocket enters the magnetic field(even though that is infinity, assume that its effect becomes observable at a particular distance) to the center of the ring ; hence gets accelerated till velocity say V2...however to leave the magnetic field the rocket has to travel same distance 'x' but this time it has velocity V2 hence takes less time to cover distance x. So even though it gets decelerated while leaving, it is not enough to bring it back to its original velocity resulting in net change
Idk if you're right or wrong but one thing is for sure , I like that you're putting forth your queries in the same medium you're taking lectures
The coil scenario was very enlightening . Thanks, very helpful!
FINALLY I see a video of the exact same things I was thinking when watching this video for the first time. The first scene is inconsistent with its coefficient of friction, and the second scene is impossible because it is impossible for magnets to do work on an object. (work is inproduct between force and distance, and magnetic force is related to the cross product, making the two vectors orthogonal to eachother, making it impossible for magnets to do work, this is brilliantly explained in Introduction to electricity and magnetism by Griffiths)
Magnets can definitely do work on macroscopic objects. The fact that two stationary magnets repell eachother demonstrates this.( The nuance is that it isn't really the magnetic field but other forces that actually do the work.)
As for the 1st one: given the fact that in the original video μ=0.1, some movement beyond the momentum conservation rule seems possible.
TSC can let the ball move on a circle, without himself moving - as long as the reaction force from the rope is below the maximal static friction μMg (where M - TSC's mass).
So that way you could get the ball's maximal speed v on circle, such that mv²/r = μMg, where m - the ball's mass, r - the rope's radius. So v = sqrt(μMgr/m).
If TSC releases the rope exactly when then ball moves horizontally with the speed v, the ball moves until the maximal rope's length. Afterwards, the things get very interesting:
If the rope has the elastic modulus k, it will stretch by some x, such that kx = μMg - until TSC remains unmoved due to the static friction.
Once the limiting x = μMg/k is obtained, the ball's new speed v' fulfils mv'²/2 = mv²/2 - kx²/2, so v'² = v² - kx²/m = v² - k(μMg/k)² = v² - (μMg)²/k. For very big k (or infinite), you just get v'=v, so no momentum loss of the ball.
After that we have static TSC, a rope stretched enough to overcome the maximal static friction, and the ball with a speed v' = sqrt(μMgr/m). So TSC will be pulled a bit forwards...
To be honest the friction seems to turn on and off throughout the video. Dunno if its just static friction or they just choosing not to animate it.
@@cameroneast8597 well for the smooth surface part, its the literal idea of " Ignoring friction, do this physics experiment"
i noticed that a lot lol@@cameroneast8597
I think that TSC will move a bit when he spins the rope. There is centrifuge force that will make him move a bit forward and backwards and if let's go of the rope when it has forward velocity then the overall force of the rope/rock from the centrifuge force will push him back a bit.
I think that however he moves the rock momentum will be preserved.
TSC is on ice, but he give example by shot the gun so I think you are incorrect
2:28 It is possible. The rocket had some initial momentum (fairly strong) that would add up to the velocity exactly after the instant the rocket is accelerated due to forward attraction. Now, this total momentum gained is quite strong that before backward attraction acts at full potential, the rocket has wayed out of the field. Indeed, the backward attraction acts, but for a lower time as compared to forward attraction (Lenz-Faraday Law of EMI where the EMF generated on the ends of rocket would be inversely proportional to time taken for the flux to change). Hence, even though the backward attraction has acted, the overall acceleration would still be positive. I would say the animation is partially incorrect as rocket wouldn't speed through at the shown exponential rate.
I might be wrong with this. I'm still learning. I'm a 17 y/o Physics aspirant. Please correct me if I'm wrong.
EDIT: For those who think I'm wrong with my concept or what I told is partly incorrect, mind watching this video: ua-cam.com/video/iyv9GhaITNE/v-deo.htmlsi=coh7gWKGErq5mfZQ
You can directly go to timestamp 3:35 in above mentioned video
Your not wrong
Was thinking the same thing if your forward momentum is higher than the returning momentum it wouldn't even matter and still act as a slingshot. Lets say for number sake, your going into a north pole magnet with a south and north pole ball with a speed of 2 with a velocity of 2 meaning 4. If the north pole sling shot grabs you and gives you a 4 doubling the speed with the velocity already being 2 making it 6 wouldn't the south pole of 2 negate it as the animation points out. I'm not into math and just see common sense here. ( Adding a correction if the magnet rings had a 2 meaning it can pull 2 from north and south. Then just the rocket without velocity pushing it would be 0 since its just a force. Still would make my point the same because the escape velocity with the magnet on the rocket would still increase the speed acting much like a sling shot.)
@@GTSgamer101 yeah coz the rocket had initially velocity, and hence a momentum, that's right...
same here
you are correct
You know that Alan's team is FUCKING AWESOME when the video called "What Animation vs Physics Got Wrong." has only 4 MINUTES and the original has 16
While i agree these scenes were wrong and it did strike me the 1st time i saw it, creative liberties were taken to create a simple yet interesting stories.
At the end of the day, similar methods do provide ways of acceleration with slightly differing setups (i.e. a railgun or a catapult)
yeah, thanks for the comment. It's good to know it's not just me who noticed. And for sure, those creative tweaks do add a simple charm to the story!
It is not only simple yet interesting stories, it is also REAL PHYSICS!
Well, the 1st one is possible. He is converting his chemical energy (The energy inside our body that we use to move our body) to kenetic energy and circles the ball few rounds to store it and releases forward. That way, he can move forward. Try it yourself if you are unsure.
2nd one is also possible. It is true that it accelerates back. But placing the magnets in the right place, this is possible. How? In first magnet, it accelerates, when it is between 1st and 2nd magnet, deacceleration power is reduced because it is again accelerated by the second magnet if placed in right place. I also seen it in action.
They are not wrong tho, look at comments they explain why it's not, I don't want to copypaste them since I'm on the phone with limited time:)
69 missed calls from isaac newton
Mr least 💀
The magnetic slingshot is possible if we changed the magnetic poles. This technique is primarily used in the bullet trains(magnetic levaiation). But we have to use electro magnets to reverse the poles. As the magnetic field of the stick man rocket is same through out the coil magnet poles should be reversed while leaving the coil so that it can push it more.
This was my first thought. I know nothing about physics tho, i wonder if there is a reason why it wouldn't work.
3:34 or the rocket magnet could be an electromagnet, running on very well timed AC current
I really would like to thank you for this video because I didn't think or even notice these, not mistakes actually, but some misunderstood concepts.
the first one can be correct, if we consider the impulse due to string after the string becomes taut
we can write two equations
-∫ndt = m(v-1.5)
above equation if for the ball, it simplifies to
∫ndt = 1.5-v this is equation 1
writing the same equation for the man
∫ndt = M[v-(-0.03)]
∫ndt = 50v + 0.03 this is equation 2
im saying they have the same velocity because of the string constraint, equating equation 1 and 2 to solve for v we get
v = 1.47/51, this is +ve thus he should move foreword
1:43 I think you are mistaken here but I also could be too, the gun analogy only works if TSC didn’t had a rope to the ball, so when he throws the ball at the max distance it will tug on TSC as it would suddenly stop and we are to assume there is very low friction. I could be wrong too
Interesting points! Happy Holidays! 🎄
Amazing. Thanks!
3:00 I was like "Isn't it deceleration?" Fortunately it is, although this seems more logical.
One little thing I noticed even with -1 experience in physics is that following the progression along the light spectrum at around 5:40 in the original video, infrared light should have >700nm wavelength (not
the speed wouldn't probably stay at zero in the magnet case . but it is not the case when the animator or even you was right. the character was already at the 1 percent speed of light so the speed will remain constant
Indeed, not only is there a lot of technically impossible stuff in that video, but he is also attempting to help those who are unable to understand physics by providing some understanding of the subject.
Thanks for the post. i watched anim.vs.ph. with 0.25x the first time because i was noticing them too.. but at the same time i tought it would be impossible to introduce to new people without some cartoon like semplifications.. its hard to explain this complex interactions with this little time.
Still its important to give a complete explaination
👍👍
Another few minor issues I spotted:
Firstly the labels for "displacement" and "distance" are the wrong way round at the very beginning. The first measurement shown should be displacement as it decreases when TSC steps backwards, and it should've expanded into a sum of positive and negative distances when TSC touched it.
Secondly, the friction of the ice surface is inconsistent - when TSC transfers its momentum to the boulder through an elastic collision, the boulder rapidly decelerated and came to a stop right at the edge of the slope. However, TSC tried (and failed) to walk forwards at the exact same spot.
Thirdly, I believe bending a magnetised pole into a coil wouldn't actually form a solenoid - you'd need to pass a current through it for that, if my understanding of electromagnetism is correct.
Very nice video though, and I appreciate the momentum calculations! I'll be honest, I didn't notice the conservation of momentum issue initially, however the magnetic acceleration definitely did bother me.
Don't forget during the flashlight scene where it shows infrared the marking shows it as "400nm" when its actually
@@Mina265 I didn't pick up on that - you've got a keen eye!
my problem was that even if it were a solenoid with current passing through it, when the magnet of tsc came closer due to change in flux there would be an induced emf and hence current would start flowing in the opposite direction and repel the magnet
I haven't found anyone else yet who caught the distance/displacement mixup; there are dozens of us!
I dont think that the magnetic field on the rocket is supposed to be like a solenoid, he simply magnetize the bar and instead of holding it straight it bends it to stick it
Actually it bothered me when the field kinda appear when the magnet hits, but its clearly scenic
respect to you bro
i know how haters can be a pain in the a$$ and know how bad it's when an hypotesis gets shattered in front of the creator
You're completely correct on both!☺
When I was discussing this with my friends, it occurred to us that this is how the particle accelerator works, and I was probably wrong, but the particle accelerator is a little bit different, so it's really wrong.
I've pushed a cylindrical magnet through a long tubular ring magnet, and it did get accelerated and shot out through the other end! Maybe it depends on velocity in a sense, where if with a low initial velocity it just ends up oscillating back and forth through the ring. But if it is already moving at a faster velocity or has a constant acceleration it doesn't decelerate fast enough to be pulled back and beyond a point the magnetic force drops significantly. I'm sure there'd be time related differential equations to describe this.
could you elaborate how you pushed it? In that case, the speed boost is gained from your original push, not from magnet. Because the magnet itself can't give extra speed based on the 1st thermodynamic law, afaik.
@@Visualization101 oh you are right! I did have to put a force to push it in (for it to be shot out), and it was anti parallel aligned magnet poles (not the parallel alignment as shown in the video)
So if I understand correctly unless there's a current source as a source of energy or external force, plain permanent magnets can't accelerate each other.
@@Visualization101But the rocket has already have its speedboost?
@@Visualization101
TSC's rocket was already boosted prior to entering the magnets via gravitational slingshots though?
If the magnetic rocket accelerattion one was possible, we could make a circle out of it and accelerate infinitely and have infinite speed
Great work mate.
The magnetic coil is actually "possible", but the distances between the rings and the strengths of the magnetic rings needs to be fine tuned carefully. The idea is that before the previous ring's field decelerates the speed too much, the next ring will "capture" it and keep TSC going.
Woah
Though, they would have to be at a " close " distance for the process you mention happen. And I’m not an expert, but they would need to have different values of forces for this to happen
you need to consider that last loop there
The fields sum, so the total field is what he described in the video. He can’t accelerate
That would not work either, as the pull of each additional magnet would be fighting against the deceleration of all the previous magnets, giving you less acceleration, and when you leave the last magnet, you would again start decelerating back to your original speed.
As @giuly007 points out, the fields (and their forces) sum, which means you can split the problem into individual magnet rings and then add up all the changes in momentum (which directly corresponds to changes in velocity as per p = mv). And each magnet separately won't give you any momentum overall (because as has been stated, you will lose all the gains after passing through the magnet), when you add up all these overall contributions (each of them being 0), you get a 0 total velocity gained after TSC flew through all of the rings.
if i am not wrong the ice does actually have a mu value of 0.1 so i dont think we can use conservation of momentum in the first case, not sure if the animation is possible or not though. This however means that TSC's velocity should decrease as he moves which it doesnt.
Still subject would not get accelerated along with the ball.
Subject will gain velocity the opposite direction of the ball thrown and friction will work in the direction of the ball until subjects velocity reaches 0
@@notweewee yeah that makes sense
My limited knowledge tell me that, Those weren't ice. But they're frictionless surface
TSC can move to the direction the ball thrown into is by converting angular momentum to linear momentum
So if you thought that initial linear force of ball is 0 then suddenly goes up. Then you're wrong. The moment TSC finished swinging and about to throw the ball. It was already entering linear momentum. Then afterwards rope tension ofc pulling him to the direction
@@DevanRAif you look closely it shows that there is friction with mu=0.1, also i dont think you can just convert angular to linear momentum they are two totally different things
@@satindra.r oh yeah I just realized there is a value on there
I mean yeah they are indeed two different things. But they are not completely independent of each other. Angular momentum is pretty much special case of linear momentum, where the movement is circular or rotational
I think you're right on the second point, which can be proven more rigorously using the work-energy theorem. Due to the symmetry of magnetic dipole forces, the work done on the magnetized rocket before it passes through the magnet is equal and opposite the work done on the rocket after it passes through the magnet. Therefore, the total work done on the rocket is zero, and the rocket should not gain kinetic energy.
Waiting for this one
It feels like the thing you should've pointed out about the first one is that his momentum stays the same while he's doing nothing despite the surface being told to have friction coefficient of 0.1. unless the efficient goes to 0 further to the right, he should be slowing. and the friction would also mess with the part with the slopes later
The first one is kind of possible due to striction, i.e. the static friction that's higher than the dynamic friction. If the recoil doesn't overcome the striction, but the abrupt pull of the ball does, you can get into motion. You did this by pushing the earth backwards. To accelerate further, you would need to accelerate the earth further backwards, but as long as you're only moving in one direction this is impossible to do using friction.
Correct, apart from one minor detail (which doesn't ultimately make a difference). The coefficient of friction is shown to be 0.1 when he's moving and when he's still. But if the change in momentum happens over a longer period of time while he's stationary, then according to F = Δp/Δt, the force would be lower than when the ball is coming to a sudden halt.
Now... Hear me out... The second coming was also moving on the frictionless surface at 8.0 m/s without slowing down from air resistance, even though the string is flapping in the wind. On top of that, the giant ball at the end should not have stopped rolling once TSC ran into it, if this was truly a frictionless surface.
it isnt a frictionless surface. If u see they showed the frictional constant to be 0.1, which is also kinda incorrect as that is a considerable amount of friction
@OBITO999YT Well, yea, it's still wrong because in the scene where TSC is shown to have momentum, he doesn't lose speed.
Great video, keep in mind the magnet loops are in series with each other so there is a chain to be made. Physics is all about perspective. Awesome! ❤
If every action results in an equal and opposite reaction, then both of these cases would result in a net 0 change. Throwing the ball pushes him back just as much as the ball pulls him forward. The magnets the video already explained. Essentially Alan is changing the math halfway through the action.
There is also a few mistakes related to non Galilean reference frames :
- The way orange gets to the rocket is wrong : the rocket does not move with respect to the ground, it is in a geostationary orbit, however, to stay in space, you need a lot of horizontal speed.
- At some point orange jumps while the rocket is still firing, but somehow stays at the same level as the rocket.
And the field of view from the black hole event horizon looks wrong : it sort of looks like what an observer that accelerate to hover just above the event horizon would see, and even then, the light would be blueshifted, not redshifted.
as i see it the rocket actually wasn't orbiting the planet and was just far away enough so gravity didn't affect it at all, in this case, the rocket is simply orbiting around the star at the same rate as the planet. which TSC obviously would also be, so the way that's set implies that that planet just has a miniscule gravity well (and consequently has a small mass) and TSC just reached terminal velocity to leave it (as we can see g reach 0 as he approaches the rocket)
The second one is the equivalent of a cyclotron for particle accelerators, but not with permanent magnet. A cyclotron makes use of alternate current, nicely timed, so that it's always "pushing". This is called a synchro-cyclotron, or synchroton. It also takes into account the change in speed (when it becomes relativist) and adapt the frequency of the current to keep up.
No its not. Cyclotrons dont use magnetism to accelerate charged particles (B does no work). It uses an AC electric field to accelerate them.
@@big_little_drift Maybe that's why I wrote "equivalent to, but not with permanent magnet [...] it uses AC"? What do you think?
@@flexable9256 Its just not that comparible. I think coil gun would be a much better example.
@@big_little_drift I agree with that, but the idea to accelerate particles close to c, and how we do it, is a synchrotron - that's why I pointed it out, even if it's different as I also outlined.
About the first equation, if he did move at all regardless of the law of conservation he should have stoppes moving until he hit the bolder since it's portrayed as a frictionless plane.
I think you're right about the second one. One magnet cannot add energy to TSC's ship; maybe there's something with multiple magnets but I'm not sure
3:21 So there is no magnetic force of attraction if the magnetics produce a constant magnetic field. There will only be a force if magnetic field is changing and that is really due to an electric field created via Ferraday’s law of induction. If you have s changing magnetic field, another one will be created to counter act the change which creates a current resulting in an electric field that will produce an electric force.
I was honestly sad at the ring magnets, he could just disconnect the magnet after crossing each one and it would work, it was so close to perfect, that is the worst thing
Where would the energy come from? You can't turn off permanent magnets
The 1st case is obvious, it doesn't really follow the 3rd law of motion where if there's an applied force, there's an opposite force. There's also a 3rd case were TSC jumped to a rocket to get the magnet but the rocket is still. I mean, in space there's no gravity (unless there's a planet nearby because space is dark...)
i just found this video randomly and i think its a good idea to subscribe. Its awesome...
For the second one, this is also possible: The TSC in the black hole further in the video might have removed the older magnets just in time.
4:15 the magnets still there
Well if you look in the video, the magnets are still on as you can still see the magnetic field, and even if he did turn it off, don't you think you would be able to see the interference?
@@user-tt3lb1yy6iyes, but they look deactivated I think.
@@user-tt3lb1yy6i yeah, they're still there. But it would have been more accurate if they vanished
Theoretically, for the magnets, instead of deactivating the magnet in order for the rocket to maintain its speed, could you switch the north and south poles once the rocket passes through?
The problem is actually the magnet being stuck in the middle. Once the magnet passes the middle, the same poles end up on the same side so the small magnet is forced to turn around in which the opposite poles point at each other.This way it gets stuck on the middle because both of the poles are attracting with the same force. So the small magnet cant even get out of the ring magnet, if it does it wont have been accelerated, and I think it would actually be deaccelerated. The only way to benefit from this is when you turn off the ring-magnet right before it interacts with the other pole, so before the magnet reaches the middle of the ring magnet.
(I think)
Thanks. I agree with u. Your explanations are correct.
I actually was irked by the second mistake for some time, thanks for pointing it out
Correction on the magnet.
If you chain a magnet where the first magnet will pull the projectile must be weaker then next magnet is but stronger and it must form a chain so it will accelerate the projectile without external force to switch it but it's still has something to pull the projectile on the end so further switch is required to make the projectile exit the magnet array
Word salad
I don't think the first scene is that valid. But I don't think your conservation of momentum is quite right.
The gun bounce back because the force that repel the force forward. It's explosion force anyway.
But it happens because the force happens there.
However, the force TSC use to create momentum did occurs when TSC start spinning the ball (which may be a lot harder on little to no-friction plane). The conservation happens there. It's centrifugal force on the string which related to the angular momentum of the ball which translated from the rotation of his hand which must have supported somewhere (normally friction on the feet).
After that he just convert the angular to the directional which is preserve by the ball stop spinning and he is moving forward.
Net force will always be zero, remember the amount of force you use to throw a ball forward the ball also exert equal and opposite force on you, however once the ball suddenly stops, the force is reclaimed back from you. Because the amount of force used to throw the ball is equal to that needed to stop the ball. Look at it in a closed equilibrium frame. This will be like pushing a car while inside it
In my opinion, due to the existence of μ=0.1, some momentum can be given to the ball without TSC moving at all (as long as the reaction forces from the rope are below the maximal static friction). So, if the ball is released while it is moving horitontally, we can have static TSC and the ball with momentum at some point.
As he starts spinning, the ball will oscillate back and forth in the x direction, thus its linear momentum in that direction will too, this oscillation will be compensated with an exactly opposite one from TSC guy such that total momentum is always conserved. When he releases the ball, he will be moving in the opposite direction, so no this doesn't work, angular momentum doesn't matter here.
This is all of course supposing he can even stand up while spinning that thing with no friction on the ground, wich is dubious.
If there is a small force of friction however, as he starts spinning the ball and TSC starts oscillating some of his momentum will be lost in friction, the faster he spins that thing the more momentum will be dissipated and in the end he will probably achieve motion when he releases the ball, although probably very small.
Well done for communicating this in the same style as the original animation. I think some ‘artistic licence’ can be permitted even though it is ‘about physics’ as the intention seems more to spark a sense of wonder or, like your own, simply drive conversation. I do agree the friction example seemed a bit off because he seemed to make no progress at all when trying to run, implying a frictionless surface even though it showed a 0.1.
He did say that he just animated but his friend was the physics nerd in this
I believe that the magnet scenario is possible since after the vehicle accelerates, it's velocity would be higher making it experience the negative acceleration for less time coming out the other end than the positive accelerating force when coming in, the principle is exactly the same as how we can slingshot around planets. Rockets and satellites experience negative acceleration when exiting the orbit of a celestial body but because of the added velocity it experiences it for less time.
This is not how gravitational slingshots work. The planet changes the direction of a satellite without accelerating (there are acceleration and deceleration, but they cancel out in the end) it in the planet's frame of reference. This change of direction together with the movement of the planet's frame of reference results in increased speed. What I'm trying to say is it is not possible with planets that are stationary relative to the star. There is no such thing as experiencing deceleration for less time, the forces and speeds (in the frame of reference of a "central" object) are symmetrical relative to the magnet / closest to planet point of trajectory / etc. Hope I've cleared this up!
Where would the energy come from
There is a way for the magnet accelerator to work. As we can see, the engine is turned on, meaning the rocket is getting constant acceleration from it. The same acceleration at a higher speed gives significantly higher energy, since kinetic energy is proportional to speed SQUARED (ty KSP for teaching me this). So if you accelerate when you have a high speed, you gain more speed* than when having low speed. Then you just need a temporary large boost of speed and a bit of power to get a permanent large boost of speed. And there you go, if you burn near the center of the magnet your engine efficiency SKYROCKETS when compared to just a basic burn. Relativity might mess with this though, so idk.
EDIT: *this should be energy, not speed.
Why didn't you just edit the word, instead of adding a footnote?
That is completely wrong too.
Yes when accelerating at high speeds you gain significantly more energy, but that does not mean in any way that you gain more speed, in fact, the whole reason why you gain more energy is because it goes like v^2 so at SAME SPEED GAIN but higher overall speed you gain more energy, but that is completely inconsequential with regards to your final speed.
And still, there is another more fundamental reason why this does not work: the magnetic field does not do any work, this means a magnetic field *alone* can never change the speed of an object, only its direction, so the magnetic field will give you no boost at all, not even a temporary one nor will it change your energy in the slightest.
As marcossidoruk has said, the energy isn't relevant to the problem. We are investigating the total change in velocity, what speed is he moving at after passing through the accelerator?
There are two sources of acceleration happening simultaneously, but that has no impact on the final velocity. Even if the two accelerations had completed their duration with an hour of time between them where no acceleration occurred, the final velocity would remain the same.
Think about what acceleration is, meters per second per second. This simply means for each second of time the acceleration is applied, you add or subtract a velocity.
Now let's look at the magnetic field. The magnetic field is a potential well, descending the well converts magnetic potential energy into kinetic, and ascending the well converts kinetic to potential. This conversion occurs through an acceleration, which varies with distance from the center, but is of equal magnitude in both directions.
Finally, we can see that this means the acceleration entering is exactly equal and opposite to the acceleration exiting, thus they cancel out. There would be no net increase in velocity, except for the velocity imparted by the rocket thrust.
In other words, the final velocity is the same with or without the magnets present, they don't contribute to the rocket's final speed.
@@ZephyrysBaumhes just lazy
dont worry about it
You reminded me another problem with the video. The rocket was on while he was in outer space, but the rocket had constant speed!
A person reviewing mistakes in Alan’s work turned into a bunch of random (for me) physics explanations that I don’t even get.
I don't understand much about physics but I really liked the video. Thanks for amazing content !
Honestly, I only really noticed or cared about the magnets. We (me and my friends) tried making railguns for ages and the big thing is that you need to disable the magnets right as they pass through so it's constant acceleration. Otherwise it just pulls them back, likely leaving you with less speed than you had going in!
thats a coilgun you're making then, railguns let the current flow between its 2 "rails" by flowing through the conductive projectile itself. doesn't need a computer to turn magnets on or off because the electricity short circuits itself through the bullet optimally
@ataarono Ah, I love learning new vocab-- Thanks for the terminology lesson! ^^
from 3:05 your point is indeed valid but it depends on whether or not the rocket's acceleration is fast enough to overcome the magnetic field and the strength of the magnetic field and we also see the rocket's main engines are on so if powerful enough can counter the force of the magnetic field together with the acceleration the magnetic field caused.
The problem with that is the fact that there is a potential energy accociated with the magnet. No matter what you do, you will have the same amount of the energy before going in and after going out.
Therefore there is no net acceleration.
Completely incorrect, force is a vector, and thus we have the magnetic force and the force of the rocket, the situation is symmetrical going into and out of the magnet and thus this component of force cancels out as the work done is equal and opposite. The fact of the rockets engines being turned on has absolutely no bearing what so ever on the effect of the magnet on the rockets acceleration
It ALLLL makes sense now.
The one about “Conservation of momentum,” Is that if he (TSC) throws it in the way he wants, he will go in that direction.
More theoretically correct way to magnet accelerate could be the stickman pulling the magnet away from the rocket, unmagnetizing it, after every pass.
Still it is impossible to create energy from nothing. The work required to pull the magnet off the rocket must be the same as the energy the rocket gets from the magnets
What TSC could have done in case of the magnets was that while passing a magnets center he could have switched his magnet till he reached the null point between two magnets and switch poles again (assuming only two have effect at once it's null point would be the midpoint of the two magnets). That would give this type of reasonable acceleration.
So tsc now can switch polarity at 80% the speed of light? Yeah i dont know if god can let alone tsc :p
@@khiemgomI'm pretty sure TSC is potrayed as a being that is very invincible
@@depufull invincible but not 80% speed of light speed or reaction time?
NGL I didn't think about that xD @@khiemgom
3:40 Hypothesis: Coils turn off when bullet reaches it.
Reality: There is a time delay between the coil reaching the bullet and turning off, and the coil turning off and then bullet realizing the absense of magnetic field. This is due to the speed restriction of our universe (i.e. speed of light).
Near light speed, the above hypothesis breaks down.
I also noticed that the magnet only Must be south. Then it is first attracted and then pushed away by those rings
As a physicist I just took it to be something cool and physics themed. It was clear it wasn’t made by a physics student lol
For sure it had Physics professional supervision
No it was not clear at all? Just because there was a small mistake? The video showed a pretty good understanding of physics and considering the friction wasn't zero, this wasn't even necessarily a mistake
Maybe it works because the rocket has its own thrust? I think.
As for the ice situation, I initially thought it was a bit weird. Now that i think about it, if you're floating in space, you need to throw an object in the opposite direction of the target you want to move toward. But then i think about someone kneeling on a spinning chair trying to spin it with repeated quick twists of the body. It works, but idk the math behind it. I even try to move the chair forward using only my body's momentum as i kneel on it. It also works. It feels like I'm using the chair to move myself forward instead of the rock and the rope. Somebody pointed out that the original video actually shows that its not 100% frictionless, so it's definitely possible. Though, would it be possible if it's completely frictionless?
It works because the total force exerted by the magnet rings are a function of time, more time is spent in front of the ring magnet accelerating so they are accelerated more in this direction than they are decelerated, because there was less time to decelerate because of the increased velocity. Both points made in this video are incorrect
@@ParoXyzmm wrong
@@laposgatti3394 Care to explain exactly *why* I'm wrong? Or do you plan to have a debate about a scientific subject by just calling me wrong?
@@ParoXyzmm The time spent on one side is exactly equal to the time spent on the other side. If any before it pass through it should come from some finite distance, while on the other side (if the system is not energetically bounded) it could in principle go on forever, hence decreasing it's speed.
Moreover as portrayed no, the magnetic field is not time dependent, it seems like a fixed permanent magnet.
And to answer @Humon66 about the ice thing, if completely frictionless the point raised in this video stands. Conservation of momentum is never violated. The fact that you can spin on a chair without touching anything but the chair itself is due to friction. That generate a force which would change the total momentum of the system you+chair (basically lending momentum from the ground).
@@laposgatti3394 My thinking is that because (I think) you spend more time in front (accelerating) rather than behind (decelerating) You would end up with a higher final velocity. Pretty sure this is justified (And not creating new energy) because it would also accelerate the magnet ring towards the point the spacecraft originally came from.
Then again I've had a bit of a think about this and the acceleration might actually be due to the Lorentz force rather than simple magnetic field interactions.
bruh I was not ready for this I know absolutely nothing about physics 💀
The permanent magnet ring coil gun could be made possible by a simple modification in the animation.
TSC leaves the 2x wound conductor coil wrapped around his rocket with open ends. And by that it is pointless!
If TSC would put a battery to the ends of the coil while approaching a permanent ring magnet, he would be attracted. If he then would reverse the battery while going trough the ring, he would be pushed away on the other side. Demonstrating the right hand rule.
Slowing down could be achieved by shorting the ends of the coil demonstrating the eddy currents, and the spark over the gap of breaking the contact could be shown.
1:03 Cuz theres no rope
3:16 you forgot the rocket is still firing
True
True
And don’t forget inertia
The magnets would still have no effect on the velocity
The magnets is still doing nothing
Thank you, that momentum thig was a big what for me too.
I was thinking exactly the same thing about the magnetic acceleration scene. I even left a comment in there (you can check it) in alan becker’s video. That acceleration seems sensitive to many people but sadly it’s not correct. That has already been demonstrated and shown to people. So thanks for the video explaining this situation to everyone.
You can also talk about the fact that while on its rocket (which is supposed to me constantly accelerating), TSC is able to grab a metal bar whil flying away from the rocket. As he is no longer accelerating with the rocket, the rocket should've continue accelerating away from TSC :/
correction: he grabs a magnet that way not the metal bar*
i think the permanent magnet slingshot could be possible only if the rocket's magnetic field would be flipped and made to repel right after passing, and flipped again, made to attract before entering another ring. However i dont see it possible flipping it fast enough while approaching the 80% speed of light
according to the video "What would we see if we fell into a Black Hole?" by @ScienceClicEN , falling into a black hole would also look different than portrayed in the animation
I think he should stay in place, beacuse every action needs reacton, which means the forces should neutralized themselfs. At least I think so...
No one talked of the ball that casually stops even if it's a frictionless surface. You can see it in the original video at 2:35
ball wont move if it drops perfectly veritcal
@@Menemen-Adam what do you mean? I'm saying that, after the stickman hit the ball, it casually stopped even if it was on a frictionless surface
@@abcde12490who says it’s frictionless, the video didn’t clarify that
We could just assume
The open and closed strings (string theory) creating rope and massive object is a bit cheeky.
TSC shrinking inside the event horizon is not really possible.
Well the shrinking of TSC (in reality it was everything else was getting bigger from his perspective) is actually possible in a special type of black hole called the Reissner-Nordström black hole (in this, the spin is zero). As you fall in this, you enter the outer event horizon, and everything looks normal, but as you enter the Inner event horizon, the blackhole will "appear" to shrink, while everything around you will seem to get bigger and bigger. This happens due to relativistic beaming, which concentrates the view ahead (making the view front of you small, which inturn makes everything behind big. Although this is all just scientific theories
oh? have you crossed an event horizon before?
Nah mate , it is speculated in no spin black hole
@@ThatUnknownDude_ Hey, I appreciate your correction! Thanks a lot for that. Now I know about these non-spinning charged blackholes.
@@untitled9787 No problem! the more you know lol
Spot on!! Even I spotted the first one, and didn't believe how noone had mentioned it in comments. That is basic physics!!
Second case also you are correct, didn't think about deceleration!!
Thank god someone else noticed that!
I feel like because you exit from magnetic flux faster than you enter, so the amount of force with which you get pulled back is less than a force which accelerates you, hence it does make you a bit faster. A bit. Turning it off after gaining acceleration will obviously make it way more efficient.
I think another, probably more realistic solution is that conservation of momentum only works with a FORCE. now there IS a force in terms of a third law pair, after TSC throws the ball (I'll get into that later) he pulls back on it with a force Ft, because of Newton's 3rd law, there is an equal and opposite force that pulls him toward the ball, Now TSC's mass is probably much larger than the small mass of the ball, so even if they are equal forces, TSC's acceleration will be much smaller because F/m = a (Newton's 2nd law).
To create a force Ft that can pull him in the direction, he SPINS the ball around in a circle, he uses his chemical energy to create a ball on a string. In uniform circular motion, there is only one force, a force pulling TOWARD the center of the circle, TSC is not pushing against the ground or anything else, TSC and the ball are in an inertial reference frame and do not move in relation to the rest of the ground (ice, tree etc.) HOWEVER he gives the ball some velocity V due to F=mv^2/r (lots of velocity)
He then releases the ball so that it goes forward (in the animation it's not perfect, but hey, it's an animation.) that ball is now traveling forward with an velocity v. He then pulls back on the ball (like stated in first part) and accelerates the ball negatively (eg, the ball was moving say 2m/s forward, but now is moving -1m/s backward) so since he now has an acceleration (a) he also needs a force F (in this case its Ft of TSC pulling the ball back to him) and as stated previously, there is an equal and opposite force opposing him, thus motion. (and the really low μ value also makes it apparent)
edit: TSC does not THROW the ball (in that case conservation of momentum applies and he does not move) he instead creates the velocity he needs by SPINNING in uniform circular motion, which gives him the velocity he needs without having to rely on another force.
as for the second one, I haven't learned about magnets yet, but it seems not too far off.
TSC is traveling much slower TOWARD the magnet ring than AWAY from it, because of how large the magnetic field is (and how fast TSC is going) there is going to be more time for the attractive force going into the magnet that going out of the magnet. So, yes there IS deceleration, however the same force of the magnet is being perceived through a MUCH shorter amount of time.
Realistically, this probably won't happen, its likely close to impossible to get a magnet lined up perfectly and in a classroom setting, you'd never be going fast enough to see this for yourself.
Y'all just mathin around while I'm gonna sit here and watch it with a smile 😁
You can also understand by newton's first law. When we throw a ball with a rope attached to it in frictionless environment the ball will have the tendency to move forward for forever but if i suddenly stop the ball by force through the rope a tension in the rope will be created and the person will move forward
1:43 you're not mistaken. The mass center should be static when there are not external forces.
There are external forces. Chemical energy from the body. The energy we use to walk, move our muscles.
@@MadhawaSadil 1 energy is the capacity to make a force, and 2 It would not be an external force.
Friction? It's explicitly not nothing (just very low).
I have very little knowledge about physics, but I think the first scenario here is possible because angular momentum through swinging the ball turns into kenetic energy when it is thrown.
Angular momentum and physical momentum have different dimension, you can't get one out of the other.
So these are the physicist fistfights I was told about
People tend to say the black hole part is unrealistic
But remember the larger the black hole is the longer you survive inside the event horizon as spegification don't happend on large blackholes outside of the event horizon
And when they reached near the center the physicis stop and we get to see a nice concept of master peice ✨
as for the second case that is absolutely possible, the distance between the magnets just has to decrease the farther you get, or alternatively the strength of the magnets, that is of course not as effective as a railgun design since you still lose speed to the previous magnet but it does work. Though the magnets appear to be a similar distance from each other and the strength the same since the sizes are the same and they look the same. Magnetic games here on YT made a "magnetic accelerator" with static magnets on a small scale if you want to have a look.
Free energry😂
To be honest, the recoil of gunfire is not utterly caused by the conservation of momentum. The explosion of gunpowder in the bore will create forces in all directions. Since those forces in vertical directions are mutually neutralized, the blast will ultimately become two hot jet flows toward exactly two horizontal directions along the gun bore. That is the main reason for recoil. Also, the magnetic slingshot case depicted by Alan Becker is indeed inaccurate, but let's assume homopolar magnets really exist in the universe and we may utilize that to implement the scenario shown in the original video.
The 1st case maybe works cuz when something pulls u with the force of equal or more than ur weight u move really quickly maybe tsc is very light weighted after all
Case 2: Another answer would be a similar system with the poles able to rotate around as the rocket is pausing through. If done right the same charge pole sweeping in after the tail of the rocket would provide extra push.