Matt & Hugh: the mystery of two balls in a can

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Dr Hugh Hunt is a Reader in Engineering at the University of Cambridge and a Fellow of Trinity College.
www.hughhunt.co...
Watch Hugh and I calculate how fast a motorbike can go on a wall of death.
• Postcards from backsta...
CORRECTIONS:
So far, none yet! Let me know if you spot anything.
[And yes: I know the audio is not great. Sorry. Hugh's mic had a load of interference and then died. Better sound next time!]
Thanks to my fine Patreon supporters for making this possible! Here is a random selection of five of them:
Everett Chouinard
Polly Hammond
Joshua Freihaut
Doug Jones
Eric Sexton
You can support me as well!
/ standupmaths
Music by Howard Carter
Filming and editing by Trunkman Productions
Design by Simon Wright
MATT PARKER: Stand-up Mathematician
Website: standupmaths.com/
Book: makeanddo4D.com/
Maths toys: mathsgear.co.uk/

Опубликовано:

17 сен 2024

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Комментарии : 488

@skyepyro7104 6 лет назад

3:25 "It's gonna move in a moment." I love how you can see how proud Matt is of that joke, and then watch him quickly die inside as it completely fails to land. Classic Parker humour.

@stylis666 6 лет назад

hahaha You're so mean! smaller than three

@MegaFPVFlyer 6 лет назад

I know that feeling all too well. It hurts, man.

@mooncowtube 4 года назад

Payback at 8:09

@DesignedbyWill2084 3 года назад

Just keep throwing them out until one sticks.

@Qermaq 6 лет назад

Ah, it’s that “two balls one cup” video I’ve heard so much about.

@verward 6 лет назад

wow. I was trying to procrastinate from studying for my mechanics test tomorrow by watching this video, guess that didn't work out.

@TheMrCarnification 6 лет назад

Ward Huyskes and I was procrastinating for my test next week

@MrCmon113 5 лет назад

Procrastinating is involuntary.

@lislehill3198 3 года назад

I was trying to procrastinate from my mechanics hw... maybe the class is the problem

@CarnelianUK 6 лет назад

Scale it up! 3 bowling balls and a bucket!

@SergeofBIBEK 6 лет назад

I was literally planning to do this.

@the_original_Bilb_Ono 4 года назад

I think friction will over come the torque at some point. But I'm not sure.

@nemesisurvivorleon 3 года назад

A grain silo and three of those boulders from that famous indiana jones scene

@abijo5052 6 лет назад

I loved Matt’s face of pure fascination when he started to see how the maths was coming together to show the experiment

@SQuark 6 лет назад

2:29 "What's going on there, engineer?" is a catchy question. It should be said after every experiment.

@TheBluMeeny 6 лет назад

"They really R"

@thulyblu5486 6 лет назад

Should have named it "2 balls, 1 cup"

@SeanByramTheOneAndOnly 6 лет назад

Would probably get demonetized, lol.

@DEADB33F 6 лет назад

Will probably get demonetized anyway the way youtube is going.

@JeanMichelRuiz 6 лет назад

man this was my first reaction too ! is it serious doctor ?

@enricoalessio5434 6 лет назад

he did 10:01

@gorillaau 6 лет назад

They probably thought about it but later canned the idea.

@Ultracity6060 6 лет назад

This trick could be improved by leaving it on a counter somewhere for a curious roommate to find. Also, finding a way to get something like confetti in the can. Or spiders.

@cillianwilliamson16 6 лет назад

Take it easy satin

@gimli3370 6 лет назад

or confetti spiders

@uiomancannot7931 6 лет назад

Or you could put razorblades on it and get away with the perfect murder.

@SchiwiM 6 лет назад

definitely spiders

@error.418 6 лет назад

satin is a nice material, +cillian williamson, pretty sure you meant satan

@skepticmoderate5790 6 лет назад

"One metric ball's weight." A Parker unit.

@asailijhijr 3 года назад

A Parker unit (™)

@MaicahRu 6 лет назад

4:39 One metric ball XD I also like how Hugh seems to miss Matt's sense of humour

@PhilippeAllardRousse 6 лет назад

Parker Sound

@paaaaaaaaq 6 лет назад

Next time Parker should have enough mics to salvage the video.

@TrunkmanProductions 6 лет назад

Hugh's mic died on this one. Sorry about that.

@unvergebeneid 6 лет назад

The background music in the beginning doesn't help either though, does it? *Edit:* which is then replaced by horrible tin and marker background noises and Matt occasionally shouting into his mic. Nah sorry, knowing these guys, there will be a second episode on the same topic anyway. I'll watch that and keep my ears and sanity.

@emilchandran546 6 лет назад

Penny Lane yeah take your precious ears off to another video mate. Or get them tested because it wasn't that bad you might have a problem. Sorry you definitely have problems, first world problems, but I was referring specifically to your hearing.

@unvergebeneid 6 лет назад

Emil Chandran, had a bad day?

@AlexHoratio 6 лет назад

I'm on half-term break from learning Mechanics M2 and this gave me a proper flashback

@ZonkoKongo 6 лет назад

Asked a friend if he wanted to work out with me after school. He didn't expect that.

@confucheese 6 лет назад

What’s up with this Parker Audio™

@SPFLDAngler 3 года назад

Its called read the fkn description for once in your lives.

@gojoubabee 6 лет назад

One of these days you should post a video where you play with a math toy and when it gets to the “working out” part it just shows Matt and Hugh on ellipticals.

@tijnhollanders6932 6 лет назад

The r's are going to cancel out. - Oh they are!

@SchutzmarkeGMBH 6 лет назад

For the purists: Cup of diameter D, Balls of radius R with 2R

@PDG200 4 года назад

What’s W and mg

@UnreasonableSteve 2 года назад

@@PDG200 W is the minimum weight of the ball on top of the can and the can necessary to prevent the can from tipping. m is the mass of each of the two inner balls and g is acceleration due to gravity

@D33r_Hunt3r_ 3 года назад

1:38 His ability to draw a perfect rectangle is upsetting to me as an engineering student. HOW!!!

@Spu7Nix 6 лет назад

Rip sound

@abelsz4407 6 лет назад

'All the Rs are gonna go.' 'They really R.' *that look*

@TheArezmendi 6 лет назад

"I've got balls"

@MisterAppleEsq 6 лет назад

It took balls to say that.

@johng7410 6 лет назад

8:11 "All the Rs are going to go." "They really R!" MAAAAAATTTTTTTTTT!

@idjles 6 лет назад

1:30 They don't waste any time with the physical world and go straight to the maths!

@MisterAppleEsq 6 лет назад

Boo, impure mathematics! Sorry.

@SydneyApplebaum 6 лет назад

loving the Matt and Hugh show!

@cheaterman49 6 лет назад

The math on this is simply amazing, I didn't get it all to be honest! Congratulations to both of you for the video and special thanks to Dr Hunt for coming up with this :-)

@aDifferentJT 6 лет назад

The 60 degrees is just a guess. Honestly Matt, one might even call it a Parker angle.

@andykillsu 6 лет назад

Jonathan Tanner The 60 degrees is right for the size of the can they used for the math. They just never said until close to the end that the diameter of the cylinder was 3R.

@aDifferentJT 6 лет назад

TheWioreks they said at the beginning that it looks like 2/3 but that was a guess.

@twistedsim 6 лет назад

Its an hypothesis that the ball are 2/3 the size of the can,

@andykillsu 6 лет назад

Jonathan Tanner They assumed that to be true in their derivation. If you don't like that then you will have to figure out how the angle changes with different cup sizes and replace the tan30 with it.

@aDifferentJT 6 лет назад

Simon Bouchard a hypothesis should be proven, it’s an assumption and should be stated as such.

@vladimircicmanec6103 6 лет назад

"All the Rs are gonna go" "They really R" "*sigh*" I LOL'd

@AndrewKay 6 лет назад

Oh, I love this Matt and Hugh Play With A Thing And Then Hugh Does Some Working Out series.

@jamiethemagpie 6 лет назад

Matt & Hugh Play with a thing and then do some working out is my favourite series on RU-vid

@yorktown99 6 лет назад

It's difficult to explain why, but there is a rather delightful sense when Matt says "balls" in his Australian accent.

@sajrra 6 лет назад

Thank you Matt for making those videos. And also thank you for honouring your patreons by mentioning them in the VideoDescription. Like you mentioned me this time :)

@qazedctgb19 6 лет назад

"Lets have a look at your thing." "I have balls"

@janJasenwa 6 лет назад

1:39 My ears are bleeding!

@andresfernando3342 6 лет назад

please do more maths using real maths like this is so good

@ErikOosterwal 6 лет назад

This "2 balls, 1 cup" video is much better than that other video with two of something and 1 cup.

@JonMW 3 года назад

I thought at first it was due to the balls deforming the can - as two opposing sides are pushed out, those forces perpendicular to the can wall aren't going to be perfectly horizontal but now also include a vertical component, which might be enough to lift the can up. But that isn't really what was happening at all, and it was because I let my assumption colour what I thought I saw when the can was thrown off.

@trucid2 6 лет назад

Good example of how to draw Parker circles.

@sickboi11111 6 лет назад

A fantastic and rare example of physical intuition!

@EGarrett01 3 года назад

1:38 In case you needed some nails across a chalkboard randomly in your life.

@affablegiraffable 6 лет назад

Even the intro is amazing

@indjev99 6 лет назад

Btw for anyone wondering what the general formula is: W ≥ 2mg(1-p), where p is the ratio (2/3 in the video). Obviously if the three balls are the same then W = mg ≥ 2mg(1-p) (obviously). Also, try working out what happens with multiple balls in the can. It is really interesting. Then for n balls: W ≥ floor(n/2) * 2mg(1-p) This means that if we have another ball on top W = mg; mg ≥ floor(n/2) * 2mg(1-p) 1 ≥ floor(n/2) * 2(1-p) 1-p ≤ 1 / (2 * floor(n/2)) p ≥ 1 - 1 / (2 * floor(n/2)) So: 2: p ≥ 1/2 3: p ≥ 1/2 (p needs to be strictly greater than 1/2 to have the effect anyway) 4: p ≥ 3/4 5: p ≥ 3/4 6: p ≥ 5/6 7: p ≥ 5/6 8: p ≥ 7/8 9: p ≥ 7/8 10: p ≥ 9/10 And so on. This means that as the number of balls increases, so should their radii.

@emperorpingusmathchannel5365 6 лет назад

TL;DW the two balls take 2/3 of the width with one of them inscribed below the initial ball. The weight of the ball on top balances the forces until its removed. That's because ball1 is taking 2/3 of the column of space while being supported by ball 2 which is suspended by the table which is greater than the constant curvature inscription support. When ball 3 is removed, ball 1's net force is the force of gravity unlike ball 2 which is the table, so the bottom 2/3 of the can rolls off the ball to meet the upper 2/3.

@MATHSOLVESZONE 6 лет назад

Incredible, fabulous and awesome!!!!!

@andykillsu 6 лет назад

#ParkerDiagram

@wierdalien1 6 лет назад

TheWioreks parkerpost

@andykillsu 6 лет назад

Alistair Shaw Nope

@Galileocrafter 6 лет назад

Three balls one cup.

@NLF02 6 лет назад

haha. the sharpee sound again. Its disgusting. But I keep watching. I promise. :D

@achu11th 6 лет назад

NutzLast i find the squeeking can more annoying, but I can definitely hear the pen way better now (unfortunately).

@lucianodebenedictis6014 6 лет назад

argh i even get chills for every comment about it!

@chrisborgars-smith2439 5 лет назад

it makes me nauseous

@MisterMajister 6 лет назад

I'm sorry Matt, can't watch this. The audio is horrible! EDIT: Okay, I watched it. It was good.

@madhuragrawal5685 6 лет назад

MisterMajister Can't resist the Parker, can ya?

@PDettarso 4 года назад

My favourite show

@TheStryper777 6 лет назад

2 balls, one cup. Loved it.

@arrowed_sparrow1506 5 лет назад

I love that you're not a smarta$$, you're a smart jacka$$. :) I love this channel.

@bdnugget 6 лет назад

I'm totally gonna do this next time I play snooker with a friend. Even going to order a canned drink for it instead of beer.

@fizixx 6 лет назад

Will be trying this out!!

@JoshuaDavidBrown-Jaded423 6 лет назад

I love your videos Matt. Always making a fun subject even better!

@Morchlasse 6 лет назад

What ist with the sound... im given up

@achu11th 6 лет назад

Lasse Mørch RIP Hugh’s Microphone. It died after a lot of interference.

@fuglsnef 6 лет назад

A lot of the videos on this channel have terrible audio, it's a shame.

@wierdalien1 6 лет назад

fuglsnef stop whining.

@chemicalbrother5743 6 лет назад

It's a Parker Sound.

@error.418 6 лет назад

He doesn't seem to use a stand-alone microphone. He mixes the audio from the camera.

@6infinity8 6 лет назад

- What do you have today? - I've got balls! 😂

@NetAndyCz 6 лет назад

One can, two mathematicians, three balls. What could possibly go wrong?:D

@Sothiamient 6 лет назад

I am so happy you guys continued using that intro XD

@Tokahax 6 лет назад

I'm sitting here spilling just a bit of time before class, but now it's time to go STUDY STATICS!!!! Thanks for a horrible distraction from my studies...

@HarvardHeinous 6 лет назад

But, but... isn't this exactly what they teach in Statics?!?

@PeterCraig 6 лет назад

I was waiting for the “two balls, one cup” pun and was more satisfied with its delivery than I had expected.

@ClownGathering 6 лет назад

"the tin will have its own moment" jesus Matt

@HeavyboxesDIYMaster 6 лет назад

This was really interesting stuff! I'm glad it was 2 balls and not 2 girls.

@RainingArtillery 6 лет назад

the last time two guys showed me 2 balls in a cup tricks I can't say I enjoyed it as much.

@HarvardHeinous 6 лет назад

Matt and Hugh have a moment while playing with their balls.

@chrismclam9172 6 лет назад

I hit the like button so fast and so unconsciously that when i went to hit the like button at the end of the video it tiook me a second to figure out why it was already lit up. That is the true Parker effect.

@chinmaykulshreshthamawar640 6 лет назад

Interesting video. Just one point that i need to make. The video did not consider the weight of the can acting downwards along the same line as W while calculating moments about point O. So the weight of the can + weight of all will have to be greater than or equal to (2/3)*mg. Thus actual minimum weight required on top of the can will be ((2mg/3) - weight of the can). For a heavy can, this can also be zero. Please do keep making such amazing videos

@7markhunter 6 лет назад

That's a very interesting statics problem, what's more interesting is the dynamic physics at time equals zero when the system is allowed to accelerate.

@deltav9784 6 лет назад

i love how complicated they make it XD

@tomgeorge3726 6 лет назад

Another great video guys, takes me back to Applied Mechanics and Structures in UNI.

@mysteryman7877 6 лет назад

Just bring this to Penn & Teller: Fool Us

@nickys11999 6 лет назад

matt its not a third more than you need it a half more than you need.

@41-Haiku 6 лет назад

Half again is the final third. Context, I guess. *shrug*

@BIWCTensia 6 лет назад

new name: Matt tries to talk over Hugh while Hugh explains what's happening

@frankharr9466 6 лет назад

Engineering and bath together at last! Who knew it could be so glorious!

@karlkastor 6 лет назад

If I'm honest I didn't get much of that (the audio certainly didn't help). But you can quite easily rationalize this result: (I'm ignoring all the rotational stuff because of course I am) All the force acting on the can is coming from the top ball in the can. Some part of that force goes against the lowest ball. Some of that force pushes against the can and some of that is pushing against the ground. So the force acting on the can can't be more than the gravitational force acting on the ball. So one ball ontop of the can is enough! 2/3 is also enough because the second ball is at a 60° slope.

@Demki 6 лет назад

3 balls, 2 guys, 1 cup.

@i208khonsu 6 лет назад

As an American I'm confused as to why there isn't anyone working out in this video.

@stylis666 6 лет назад

Don't worry, it's not because you're an American. You're simply an idiot. _Working out a maths problem_ translates very well to pretty much every language on earth and everyone who got past kindergarten has no issues understanding the phrase.

@lionhardt75 6 лет назад

Setekh Wow. Don't you think it's possible that their comment was meant in a joking way? If they didn't know that "working out" has different meanings in British English versus American English, why would they specify "as an American"? They would have simply commented, "Why was there no one working out in this video?" Adding "as an American" indicates that they do indeed understand that the phrase has different meanings, and it is therefore likely that they also understand what it means in the context of this video, making it likely they were joking. A little logical thinking would go a long way toward helping you be a nicer, more understanding person.

@i208khonsu 6 лет назад

Yes, of course my comment was sarcastic (not really surprised I needed to point that out). However in America it would be more common to leave out the -ing and rephrase it a bit. e.g. "Play with a thing and then work it out."; this is because the term 'working out' has a very strong connection to exercising at a gym. Perhaps Matt though made the title a little ironically too, i dunno, just wanted to make a silly comment.

@stylis666 6 лет назад

Austin Reynolds Perhaps, but I left the 90's behind me when the 21st century began so I forgot about the stereotypical gazillions of work out adds and videos America has. Sorry for assuming that Americans got smarter since then. I'll try and not overestimate people, if that makes you feel better. That's a relief! I feel like I am so much nicer and more understanding now.

@lionhardt75 6 лет назад

Setekh So, just to reiterate, neither myself nor the original poster ever thought that this video was about exercising. We just noted that the phrase "working out" is only really used to mean exercising in America, but we were both smart enough to understand that it carries different connotations in other English-speaking countries. The original poster then made a tongue-in-cheek joke, which you misunderstood and attacked them for. I think that the attack was unfounded, narrow minded, and rude.

@daemonguy2 6 лет назад

A half more than you need

@MagisterMalleus 6 лет назад

Hooray! Another great episode of M&HPWATATDSWO

@uncommonsense360 5 лет назад

Literally just took a statics test on stuff like this today, and I thought I would watch this to relax. It backfired.

@colinsmith6480 6 лет назад

well that video took me back to my advanced Applied Mathematics A level, over 30 years ago !

@DestroManiak 3 года назад

the squeaky felt tip pen is kind of killing me lol

@Your2ndPlanB 6 лет назад

But what if you don't exactly know what the ratio of the diameter of the ball to the diameter of the cup is? This working out is rubbish, the assumption 2:3 is completely unjustified! I demand a formula for arbitrary ratios (between 1 and 1:2, of course)!

@andykillsu 6 лет назад

Your2ndPlanB you will only get that nice result for this case however I do think they should have did it for any size diameter cup.

@015Fede 6 лет назад

Your2ndPlanB welcome to physics, we usually do rough estimates

@Your2ndPlanB 6 лет назад

Pah! Away, physicists! The general case is always superior!

@SchutzmarkeGMBH 6 лет назад

Did the general case of balls of radius R and can of diameter D. Leads to W=mg(2-4(R/D)).And I'm a physicist btw ;)

@Your2ndPlanB 6 лет назад

Much obliged! That's not even that ugly.

@Ajoscram 6 лет назад

8:08 I laughed WAY too hard at this, I feel so dumb

@ghanshamchandel1854 6 лет назад

that title again is hilarious!

@jumperluk6267 6 лет назад

341.592 subs? Damn such a Parkersquare of a channel!

@adelarscheidt 6 лет назад

8:09 "- All the R's are gonna go... - They really R!"

@adelarscheidt 6 лет назад

That was the shortest laughter I've ever seen in my life.

@user-wd4yj7ck6m 6 лет назад

How did that petition go Matt? Oh, let me guess, it was a Parker Petition wasn't it?

@cowsome12 6 лет назад

Matt and Hugh star in 2 balls one cup ;)

@AlexKing-tg9hl 5 лет назад

I know elementary physics but have no idea what any of this math means

@neilisbored2177 5 лет назад

Somehow this has a more suggestive name than "The three body problem".

@IllidanS4 6 лет назад

The title should have been "Two balls, one can."

@tncorgi92 5 лет назад

1:39 that noise... like nails on a chalkboard.

@jeffflowers5489 6 лет назад

Math is indeed fascinating. I was working with putting circles into squares and squares into circles and I was amazed to find out that (old news to you I'm sure) a 50mm square x .70710678118654752440084436210485 = 35.355339059327376220042218105242. And that times the same .7071067... = 25.00 which is exactly half of the starting 50. Wow! To get numbers with such loooong decimal places to end up a whole number so fast.

@andresfernando3342 6 лет назад

this video is so good