Most Collisions Are Secretly in One Dimension

[@EebstertheGreat]

The equations you showed actually have two solutions, which makes sense, because the energy equation is quadratic. For a perfectly elastic collision, the other solution is that the objects just pass through each other unaffected, which of course also conserves momentum and kinetic energy.

[@maxluthor6800]

this video was just clickbait man. Even confessed to it troughout the video.

[@Archimedes.5000]

@@maxluthor6800 in what way?

[@angeldude101]

This kind of is what happens for wave collisions, though some weirdness might still happen while the two waves are inside each other.

[@Hannah_Em]

There's still only one _physical_ solution, to a 2-body collision in that case though tbf; there's a mathematical second solution, but in physical terms for most objects it will involve a physical impossibility (eg two solid objects passing through each other without interacting)

[@cfv7461]

@@Hannah_Em i guess that's why he said "in our universe"

[@hendo1877]

Wow, 5 months with no video and then i stumble across this one minute after it goes live

[@kaijemgaming]

Yeah me too I thought what kind of channel is this? And how did I get notification from this channel ... Did I even subscribe this channel?¿😂

[@DeLewrh]

@@kaijemgamingit's minutephysics lmao, what do you mean? 5 mil subscribers isn't nothing

[@Strongify03017]

💀

[@MrSafa61]

If we are on youtube every second, can we really be surpirised about a coincidence like this?

[@firstname405]

@@MrSafa61 yes

[@Yupppi]

I love it when there's a sentence or two of text added on screen and it flashes for a bat of an eye so I have to rewind twice and then accept I need to pause on the third rewind.

[@LookingGlassUniverse]

Great video, and it’s so good to see you back! I’d never considered that fact that even when there’s energy loss, conservation of momentum and energy uniquely pin down the velocities. And I hadn’t heard of the secret axis of collision either, but it makes so much sense! Feels like these two points should be added to kinematics classes.

[@LookingGlassUniverse]

Also, what did you use to simulate all those collisions??

[@johnchessant3012]

hi Looking Glass Universe

[@justinmullins1112]

I have an BS in physics, and this point was included in my Classical Mechanics course. Picking the right coordinate system to describe your problem in can cut down the algebra work in half or better.

[@Exachad]

​@@justinmullins1112 Picking the right coordinate system is taught in high school physics too. Take the case of a mass falling off a slope for example. That way we only have to break down gravity into the component parallel to the surface and the component perpendicular to it. But I don't think it's taught in the context of collisions because it's more complicated to work with.

[@tomfeng5645]

@@Exachad At least in my locale, that's exactly right - 2-D collisions are for the most part glossed over and vastly simplified, with the full treatment left to university. Part of it is probably also due to vectors being formally only taught at the last few months of HS, which means physics can't make any mention in-curriculum of projections, dot product, cross product (makes the magnetism calculational portion... *interesting* to teach), and vector maths in general is highly limited.

[@EgoLTR]

Great video but all those flashing texts are a bit annoying. I love to read the extra complexity you put in the notes but on a phone or smart TV it's almost impossible to pause at the exact right time. Please keep them in the screen (a bit) longer in the future

[@jursamaj]

This. This is probably the only minutephysics video I haven't up-voted. And it was borderline on getting a down-vote.

[@hanswoast7]

Yep. Even on PC it is hard :(

[@kunedroid3446]

It is really annoying.. it seems like our fried is very shy of using the "incorrect" words and tries to cover his "imperfections" without giving out the slip... Still enjoy the video, but YES - ANNOYING! Either correct yourself properly or own the slips...

[@effyelvira]

Not a bit, it was REALLY annoying

[@thorr18BEM]

I thought it was just that my coffee wasn't working yet and dawn is not the time for physics.

[@Leonardo-G]

I remember having to figure exactly this out when making a physics simulation for coding practice. At first I had no idea how I was going to handle collisions in 2D, but then I realized I could simply look at the collision from the frame of reference of the two colliding objects (ie their total center of mass) and that simplifies things to one dimension.

[@spaceowl5957]

Whoa I would’ve felt so smart coming up with that :O

[@Ziplock9000]

But then you have to translate it back into 2D or 3D to get the correct x,y,z offsets so it's easier to just do the calculations in 2D or 3D which is how almost all simulations work

[@faffod]

So glad to see Minute Physics back! Thank you. And though I don't know how much more it takes to animate, I think that the animations are a great addition. I would ask that your *caveats and *clarifications be more than 1 frame, it is distracting trying to scrub to find the one frame that had something I wanted to read.

[@Deus_Auto]

Try the "," and "." keys.

[@mrdragon5142]

@@Deus_Auto TIL about the "," and "." keys. Thanks!

[@willythemailboy2]

@@Deus_Auto A useful workaround but a workaround is not a solution.

[@romanski5811]

@@mrdragon5142 Also when you open the transcript (the three dots next to save to playlist), then you can search for specific words or phrases with Ctrl + F, and it'll jump you to the exact minutes/seconds every time it's been said.

[@vict0rmike]

As a somebody who deals with computer simulations of mechanical systems for living, I can assure that simulation of collisions is actually a really complicated topic. If you have a system of multiple interconnected bodies, i.e. you are dealing with multibody system dynamics (that is the scientific keyword here), you can no longer deal with mass and velocity only, but instead you are, usually, solving accelerations from a system of nonlinear differential equations that describe the dynamic force equilibrium of the system. Contacts are treated as external forces, which means you need to be able to solve both the magnitude and the direction of the force, which is not a trivial task when the shape of the object is complex. Also, for contacts to be actually any useful, you need to model the friction forces at the contact points, which is not exactly trivial either, since, among other reasons, many models fail to create any force at zero velocity. In total, this means any contact can need, depending on the models used, 4-8 individually tuned parameters to work. Of course, if you are making a video game, things can get a lot simpler since accuracy doesn't really matter. But for an accurate simulation that you could use for engineering purposes, things are quite different.

[@PavelKostromitinov]

As a somebody who used video game engines to simulate collisions for some simulator software, I can tell you things maybe get simpler - but they are definitely not simple. A lot of work goes into tuning simulation steps, and fake masses and so on, so that objects behave in a 'realistic' way and still not require a thousand simulation steps a second. And remembering how difficult it is to simulate a rope still makes me wake up at night...

[@Alexander_Sannikov]

actually for engineering purposes things are often much easier than for games because you can do calculations offline. physics in games is realtime and both the collision detection system and the solver need to be fast enough in order to run in realtime and they also need to degrade gracefully when it just can't keep up. for engineering you can often bruteforce very simple/reliable/slow methods that are simply not viable for realtime purposes.

[@vict0rmike]

​@@PavelKostromitinov Oh, I never claimed they were simple :) In some ways it is actually simpler to aim for physically accurate solution, since you can, at least in theory, rely on hard data when tuning the system. However, not all parameters are available and not all parameters have a physically clear meaning, so you will still end up tuning your system to make it behave in realistic manner. And yes, ropes are nightmare material, even at around 1 millisecond step size where I am working...

[@vict0rmike]

@@Alexander_Sannikov Here is the catch: I am working with real-time applications. But you are correct, if you can brute force a solution offline, things get simplified, since you can use actual parameters and you can use more advanced integrators to get the accuracy needed.

[@felipelopes3171]

Agree with this a lot. What this video is basically saying is: if you ignore everything that makes collisions complicated, they become simple, which is something rather vacuous. The fact that collisions can get pretty complicated is the reason something like the LHC exists, because by colliding things you can see how the physics works by looking at the cross sections.

[@octaviosilva5808]

This is one of the first video by minute physics where I actually know and understand what they are talking about Newtonian Mechanics lol

[@didack1419]

Good for *us* lmao

[@scidro1115]

🤣

[@taconator1213]

This is a fantastic way of introducing and understanding vectors imo

[@blazernitrox6329]

I'd never thought of it this way. One of the first things we were taught in High School (AP) Physics when it came to collisions was that you always separate the vectors into their components, but it never occurred to me that essentially we were computing a 1-dimensional collision.

[@Ziplock9000]

Because you'll have to convert it back into 2D or 3D for it to be relevant to any experiment or simulation

[@HilbertXVI]

@@Ziplock9000 But that's a much easier task.

[@willmungas8964]

It’s one dimensional along that arbitrary axis… which you can describe as a vector, which is more convenient for understanding

[@Ziplock9000]

@@willmungas8964 For understanding maybe, but not for computer simulations which always use separate x,y,z.

[@hukuzatuna]

I'd love to see the same kind of video for rotating objects - spinning tops colliding, theoretical spinning spheres, maybe touch on spinning black holes....

[@LagAttacktoSlay]

I doubt there'd be much rebound when it comes to colliding blackholes (for the singularities themselves, at least), but it's a really interesting topic that you can find a really neat explanation of using TODAY'S SPONSOR: BRILLIANT

[@SECONDQUEST]

@@LagAttacktoSlay what happened to your dream of making gaming content?

[@dott8045]

-Matter didn’t create anti matter -Anti matter didn’t create matter (Both of them were present at the time of big bang) -Both of them didn’t create themselves. -Both of them came from an unimaginable source, that unimaginable source created matter and antimatter (everything) thats why it is known as “the creator” of everything. ------:::::::::::::::::::::::::::::::::----- - that unimaginable source/creator has created sin and virtue which are opposite to each other, - logic says every action has its own reaction, so the reaction of sin is different than the reaction of virtue, - the creator has created prophets to let us know about each and every detail of sin and virtue, also about their reactions, Thank you :)

[@3mpt7]

'Most 3D collisions are really quite simple, but don't worry, because you can make them really complicated by over-simplifying to 2D'.

[@rufusapplebee1428]

@@LagAttacktoSlay blackhole singularities don't follow exclusion principles ( and behave partially as dark matter in that regards. Although in my personal opinion singularities are more likely high energy waves of non gravitationaly unified strings but unified in electromagnetic, weak nuclear and strong nuclear forces, furthermore, the dimentionality of these non gravitationaly unified strings is zero ( which means they are pure energy which still interacts with Higgs boson and Higgs fields ) ). Blackholes still warp space-time via gravitational waves (Higgs fields) though.

[@jpe1]

Why the f*ck are the onscreen asterisk notes displaying so briefly? I’ve never had to rewind a video so many times as this one, going back repeatedly to try and read the notes before they disappear after just a few frames. If it weren’t for the overall excellent content I would have given up and watched something that doesn’t test my reflexes on the pause button.

[@Gebohq]

The amount of split-second footnotes showing up seemingly every second of this video really makes this video feel like a drug ad. "It's simple!" followed by a minute of disclaimers.

[@Gem-In_Eye]

Bro, you should have made this 5 years ago when I was studying collisions in Physics. This definitely would have helped.

[@dirichlettt]

My physics teacher showed us a way to calculate collisions by switching to the center of mass's frame of reference, which a) turns the problem into a 1D collision and b) is really easy to solve then convert back to the lab frame.

[@carultch]

That is a great trick. It turns the giant quadratic equation that would lose half the students, into an equation where it is easily isolate the unknown variable with simple algebraic steps. It also gives us the result that for elastic collisions, the two objects simply reverse direction in the center of mass reference frame. I feel it even gives you more insight as to what is really happening, as well.

[@masterdj21]

I was internally screaming "what about rotations!" the entire video, but then I sighed in relief when I saw the note at the end.

[@KarimMaassen]

Great vid! Just a little remark: Those side notes flash by way too fast. I don’t want to stop the video, scroll back to the exact frame it was shown.

[@Nors2Ka]

It's cute that you have those single frame footnotes, but it's only a distraction when not stopping to read them and a nuisance when you have to interrupt the flow of the video every 10 seconds or so. And it's pain on mobile. Maybe scoot them over to captions?

[@srinikethvelivela2692]

This basic physics but presented with beauty !

[@angeluslupus]

Look - if you're going to keep putting up "well, technically..." and other such caveats, PLEASE leave them up for more than a millisecond!

[@grproteus]

We have been trying to realistically simulate collisions with computers for more than 30 years now, and we still have to use hacks, like virtual thickening of surfaces, smoothing out surfaces and their motions etc. When you measure time in discrete intervals collisions are a lot more complicated. In order to know where the "hidden axis" is, you need to know the exact moment of collision, which is near-impossible in a system where time is discrete and of limited resolution.

[@dr3yk]

The amount of 0.1s-long notes in this video is over 9000. is it just me who struggles to watch the video properly because of them? I have to constantly pause and rewind to read the notes

[@TheRexisFern]

It's all really simple, but also complicated. You know, science.

[@broor]

0:54 this feels unreasonable

[@SgtSupaman]

Great video! If we ignore all the reasons multi-dimensional collisions aren't one-dimensional, they are secretly one-dimensional! The profundity here boggles the mind!

[@ajeetgary2706]

Dang it, this achieves what the giant rant I just commented does in one line 🤣

[@Gustav_Kuriga]

Pretty much.

[@PopcornColonelx]

Incredible animation this time! Great work!

[@sanderbos4243]

Awesome, loved the explanation and the animation!

[@jonnupe1645]

Dimensions are (in other words) directions, time can also be considered a direction ('arrow of time' for example). So a way to interpret this video is a single dimension plus a time component.

[@Cl0ud897]

You should make part 2 for this video which will explain rotations. I really love Newtonian mechanics!

[@jayludus7737]

I love having to stop the video every time additional text is shown for a fraction of a second

[@narfwhals7843]

I have the creeping suspicion that you do not, in fact, love having to stop the video.

[@eccentricOrange]

Yay! You're back! What were you doing, Henry?

[@pinkace]

The animations were so cool! :) Do it again!

[@13thravenpurple94]

Great work 🥳Thank you 💜

[@Corruptedhope]

Wowwww. It was such a long time minutephysics uploaded a video! Even though minutephysics have more science that other people can bear, it’s still great!

[@sumantpes]

minute physics, millisecond notes.

[@Edgemaster72]

All the collisions at the end were so satisfying to watch

[@AnnoyingNewslettersPage6]

That reminds me of when I got rear-ended by a Toyota Tundra. My Dodge Stratus was the stationary object at the light, the Toyota tundra was traveling at about 50mph and did not apply the brakes. My car slid forward about 10 ft. The Tundra collided with us again, sliding us forward another 10 ft and folding the trunk lid through the back window. The Tundra collided with us a third time and buried itself to my back tires, finally bringing this abbreviated Newton's Cradle to a screeching halt. The driver offered me any amount of money to let him leave the scene of the accident. I asked you've been drinking, haven't you? He admitted as much, and his breathalyzer results were just barely over the legal limit. There were five other vacant lanes he could have swerved into if his excuse of, oh the brakes weren't working, were valid.

[@AntonMadness]

And again, I need to watch your movie twice. First time I'm just totally locked in to the awesome bass backing track

[@prosamis]

Correct me if I'm wrong but are the examples here just perfectly elastic? We have the case where one of the objects become embedded in the other, which Im surprised isn't even mentioned

[@SuperYoonHo]

great to have you back ! you rock dude! :P

[@HershO.]

Ngl I first thought this was an old video until I saw "19 mins ago". Great animations.

[@anthonyj.finley3704]

I know the channel is called “minutephysics”, but could you make more 10-15 minute videos? I feel like this just scratches the surface.

[@dave900575]

I suspect that in reality there is probably a great deal about the science in your videos that I don't understand because, you know, maths. But ignorance is bliss and I still enjoy them and look forward to them because I always learn something.

[@asmaar566]

Welcome back man

[@orangesite7625]

This is the first video I saw and I subscribed 🔥🔥

[@stephengraves9370]

This is the secret to physics: It's not hard, just pretty damn tedious

[@Nylspider]

Fr lol

[@wolfamadeus6932]

Sounds more like mathematics, expecially for people with ADHD.

[@l1mbo69]

Not when you have computers

[@Barnaclebeard]

He's lying. It's super hard.

[@derblaue]

It's all of it. Some things are easy, most things are hard. Some are trivial, some are tedious and a lot are extremly tedious. Even simple things like a pendulum get really tedious once you do physical pendulum, air resistance (and any onther resistance), laminar and turbulent flow, flow separation, air pressure, air humidity, coriolis force, propagation of uncertainty, vibrations and flexing. I probably missed some.

[@byronwatkins2565]

Macroscopic collisions also have friction, but still, the sum normal + friction points in a single direction. We do need to allow for rotational energy in that case. Long-ranged interactions with energy loss/gain; however, can be asymmetric.

[@psikoexe]

❤❤❤❤minute physics is love... I commented about your absence on your recent community post yesterday, and here you r today

[@ThoughtinFlight]

Back in high school I was very weirdly obsessed with physics engines for games, can't believe how much time I spent on these equations. Thinking about them still makes me feel giddy. Then I had advanced dynamics as a post-grad, life changing most fascinating shit I ever studied. Also the most difficult.

[@ValerietheLovelyDeadlyItalian]

its been a while since ive looked at one of your videos. I still remember back when i was watching you channel, CGP grey, and Vsauce.

[@whatitmeans]

There is a subtlety in the scenario of the comming mass transmiting all the moment to the other one so the incoming stops moving: the only possible way for a solution to a differential equation to becoming zero forever after a finite ending time, is by requiring of having a "singular point" in the differential equation so it is possible to brake uniqueness of solutions, allowing to have a piecewise solution that becomes exactly zero after the collision time. This is a issue widely underlook in current physics, and it is understanding that is mathematical impossible to achieve systems with finite ending times without abandon uniqueness of solutions... current models at best vanishes at infinity, but never achieves accurate endings in finite time.

[@niezbo]

Many years ago I came up with idea, that there's no such a thing as "random". That's the concept that allow us to comprehend thing we don't understand. If we could have a power to define every single possible variable of any event, we could tell the outcome of that event.

[@Brad-gc9cq]

That's certainly what Einstein believed. "God does not play dice". Current interpretations of quantum physics may say differently, but who knows what the truth is once (if) we have a full understanding of the quantum world. I have to agree that I'm uncomfortable with the idea of a universe that is fundamentally random, and therefore in some way non-causal.

[@niezbo]

@@Brad-gc9cq no, no. Even a spooky actions at a distance, could be explained somehow. We didn't get there, probably never will. There's a lot a things we don't understand, so maybe there's a chance to understand quantum entanglement someday.

[@dr.uncertain6732]

I have fallen in love with this kind of Physical thinking. The work of David Hestenes "Geometric Calculus" works to formulate all physics with the dynamical vectors as the basis. It makes these realizations much more apparent. 10/10 recommend

[@HienNguyenHMN]

ah, a "back to basics" minute physics video. It's why I subscribed in the first place!

[@adityakhanna113]

0:46 Holy shit. how did you even do that animation?!

[@AnotherRoof]

Anyone else hate the text flashing up over and over? Something is either worth saying or it isn't. If it's worth saying, take the time to say it. There's even a whole caveat paragraph at the end covering some of the points previously raised, no reason why the other stuff couldn't be covered there too without distracting the viewer.

[@kevinlapsley8227]

I think you put it brilliantly my friend. Scattering and subsequent spin variations I find less important. I know people want to know exactly what is going on with all the composite particles of the collision, but the predetermined mechanism is clearly there and the spin variations are likely do to mass clumps

[@micahphilson]

Those little notes coming up at the speed of light and disappearing after like 3 frames are so annoying. Even not on mobile, I keep having to go back to read them, which is very disruptive. If they were twice as long as that, I could at least pause as a reaction and read it in time rather than going back 5 seconds.

[@AngDavies]

Was thinking about this the other day- two photons colliding, and realised that without something weird and 2D happening, there's not actually a meaningful distinction between colliding and phasing through.

[@ajeetgary2706]

Crazy right!! That's because there's not a meaningful distinction between the two photons ~ you and your friend throw a photon at each other like straight-on and they overlap in space during their journey and then you catch them: when you ask your friend "is this your photon? or is this mine that bounced back off of yours?" the question has no meaningful answer b/c you never gave a meaning to which photon is which besides it's initial location; "which photon is which" isn't like a falsifiable meaningful sciencey thing

[@nick76dune]

Great to see a new video from you!

[@IIT_Delhi_LoVe]

Great explanation brother.

[@Roberto-co4uk]

Very cool video on the basics of kinematics of collisions. Love it!

[@afik1200]

YES! I waited for this

You missed a great opportunity to explain that, in fact, there are 2 solutions for the conservation of momentum equation. One is what you presented. The other one is to keep both velocities the same as they were before the collision. It's not physically possible, but it's a valid solution for the formula.

[@latschezarkotsilkov2227]

If you were to implement the other formula in a collision simulator, this is what you'd get: kzbin.info/www/bejne/iaLTepapg5V5iqs

[@viliml2763]

It is possible. In fact the system was precisely in that other solution before the collision. Notice that the equation only mention velocities, not positions. At the moment of collision the system simply jumps from one solution into the other.

[@abhi_137inverse]

What about colloision of matter and antimatter? please make a video on superposition principle..

[@hrperformance]

Firstly, this was a fantastic video and I really appreciate the effort put in. Im going to watch more videos from this channel for sure. I do think that the *captions should be visible for longer though. Unless I'm not aware of a method that makes it easier to pause within a particularly small time interval, I really think they should be up for longer 😅 it's more than likely because I'm dyslexic and can't read quick enough but I doubt I am alone. Thanks for the great video!

[@alfredmason-fayle6075]

'.' and ',' keys can increment by individual frames on desktop youtube

[@Ricocossa1]

For those who like to think in terms of symmetries, in 3D, if you combine translations, rotations, and frame changes (boosts), there are 10 symmetries that are imposed-i.e. ten equations to be satisfied. The variables of a 2->2 scattering problem are the four incoming and outgoing momenta, which account for 4*3=12 variables. So in total the collision depends on only _two_ variables, which you can take to be the incoming energy and relative momentum.

[@Rakeshkumar30]

These days videos are sparse...it's always a pleasant surprise when I get the minute physics new video notification

[@brainyLightBulb392]

The animation looked awesome. Does anyone know what software is being used for these?

[@limpnoodle3272]

I hated science in school, but your enthusiasm & interesting tid bits make it easy for me learn & grow my opinions :)

[@p20104]

that ending was very satisfying to watch

[@icecream6256]

2:58 they had me in the first half with the curious ngl

[@tomwilkinson9235]

"In our universe, the equations have a unique solution" surely there couldn't even hypothetically be a universe where the logical deductions involved were invalid?

[@SporkleBM]

Glad to see minute physics again! And this time I understand more of this concept because I'm actually learning it in college now! So that's really neat ✨

[@elgatto3133]

I learned this in dynamics but it's cool to hear from a different perspective

[@w0tch]

How is it different from any other physical interaction with a deterministic perspective ?

[@ajeetgary2706]

Wow, bringing out the Variational Mechanics hammer I see ~ totally, like, "If the only independent variable in this problem is time, then, the problem is 1 dimensional, b/c there is 1 time dimension!"

[@w0tch]

@@ajeetgary2706 ahah exactly

[@jacksyd]

Great video! Question: does this not just follow trivially from a change of basis vectors? Or am I misunderstanding the result!

[@HilbertXVI]

Yes, moving to another reference frame is just a change of basis in 4 dimensions

[@JustLukeE.]

OMG it's been so long, I thought this channel had closed

[@TheOtherSteel]

I don't know what your personal situation is, but if I get a vote, it's for more minutephysics videos! You have one of the best channels on KZbin.

[@JesseBrohinsky]

Is object deformation completely contained in the energy lost part of the equation?

[@Michael-xd8bc]

Yes

[@fluffymassacre2918]

Yes

[@EebstertheGreat]

Any energy lost due to the process of deforming the objects will just be heat, and it won't affect the motion of the center of mass (beyond slowing it down due to said lost energy). But when taking rotation into account, it can make things more complicated.

[@Joe-lb8qn]

NIce. A genuine question triggered by your very first example at 0:48. When one object hits a stationary and both have the same mass, the first one stops, the second one moves on at the same speed as first one. Conservation. But .. so it would be if, for example, the first one continued at 1/3 the speed and the second at 2/3, or any other matching set. And with the m and m.20 example next, why not the m stops fully (rather than rebounds) and the second goes at 1/20th which would be more in keeping with the first example, eg the moving mass imparts all its momentum to the mass it hits.

[@anvithequarsonist]

A new minutephysics video? Am I dreaming?

[@knyri3153]

Can we please keep the asterisk comments on the screen long enough for someone to read? Having to rewind and attempt to pause on them is really annoying

[@Suppenfischeintopf]

Yay, I now have to find a video player that allows me to skip through individual frames just to read the footnotes 😒 This tendency of adding text for only a split second in videos always pisses me off (try to pause the video in the right moment on your phone, glhf), but this video takes it to the extreme *Edit:* TIL that you can skip frames on KZbin with . and , (mobile is still tedious though)

[@cinemagoose]

You can do it on youtube with the period and comma keys, which go forward and backward one frame, respectively.

[@ragnkja]

You “just” have to switch to a desktop or laptop, and use . and , to move one frame at a time. Annoying when you might not have immediate access to such a device, I know.

[@aleksandr_berdnikov]

Agreed 100%

[@l1mbo69]

Just pause, go back one second, and switch to ×0.25 if you're on mobile. It's tedious but works fine

[@lux_incola4224]

You seem to have missed the point: "minute" physics is the foundation this channel was laid on, and they *have* to save time somewhere (or rather, everywhere) Also, as I recall, all the shortest ones are just "correctness footnotes" to ward of the "Um actually[s]" down here in the comments

[@Ishan.khanna]

Woo Minuephysics is back

[@johnchessant3012]

Very cool! But how do you find the secret direction for a given 2d collision?

[@danieljensen2626]

Seems like a pretty standard eigenvalue problem.

[@chrisg3030]

1:39 "Most collisions in 2D or 3D result in a net force between the objects which is only in one direction, typically perpendicular to the surface where the objects collide". Does this account for circular impact craters (on the Moon for example) even when the collisions themselves aren't in a perpendicular direction?

[@Ebani]

It's simpler to solve equations separating them by axis than it would be to do them as a whole, this applies to any equation that deals with dimensions as the result is the sum of the contribution of each axis/dimension. This is a very common topic in science so no wonder ppl are calling it clickbait.

[@Lonelykea]

What did you used for the collisions ?

[@ilikaplayhopscotch]

The little caveat pop ups felt WAY too fast. I can usually pause quick enough to read them but I had to rewind for each one this video.

[@spaceowl5957]

But doesn’t this only work for spheres? If you hit the edge of something long then it will start spinning and stuff will be more complicated right?

[@elysenna]

whenI was young I tried to write my own collision engine and it took me 5 years to come up with this solution

[@GapWim]

1:55 Flashing text: *Impulse

[@theultimatereductionist7592]

I wish you would talk more about numbers of variables (V) and numbers of equations (E) for multiparticle systems and confirming or disproving that V=E. Because I worked on this problem, trying to calculate in general, and I could never get V to equal E. I always had V > E. So every collision problem I had with more than 2 particles and in 3 dimensions was underdetermined.

[@the_falcon0power150]

I’m going to try this on my next physics test, wish me luck!

[@irfanjames]

Sir, you just inspired me to make a collision simulation. (in my beloved C++/SFML of course)

[@haoding2035]

1:17, I get it you can cancel the "1/2" in terms regarding kinetic energy. But shouldn't the lost energy term be doubled?

[@WanderTheNomad]

I think this video has the most side notes of any Minute Physics video

[@NathanSMS26]

A video on elastic collisions would be the perfect time to talk about newtons pendulum