8th Brain Teaser: The Dog and the Can

[soursharpie]

SPOILER: 0 mph! if he doesn't move, the can won't make a sound

[o0thisismyusername0o]

0 m/s (what do you mean,comment isn't long enough! is it long enough now?)

[lishadadishda]

There is no dog O_o

[einherjen]

stand still or run at the speed of sound.

[3780317]

he said the speed of the dog so 0 m/s

[Horinius]

Just use a rope short enough so that the can doesn't touch the ground ;)

[MrKoiking1]

any speed, just slice the dogs ears off.

[234nightfox]

0 miles an hour, 0 feet an hour and, 0 inches an hour

[artusart]

You would like to offer us your aids brain teaser????

[Andryx123]

3 variants:

1. the dog moves with any speed if he runs in a circle whose ray is the length of the rope, this way he doesn't move the can

2. the dog moves with the speed of sound (340 meters per second) so that the sound never reaches him, but we can't find a dog wich is running so fast

3. the dog stands still

Sorry for my English.

[ZetaNeubourn]

@Andryx123 I like how you thought with the second answer. XD

[nicochunger]

@Andryx123 i think its not necessary to go that fast, sooner the dog will run so fast that the can will fly and dont touch the ground.

[einherjen]

@nicochunger yeah, but we dont have enough info to tell at what speed that will happen. But i agree...

[joejacksonriley]

fast enough so that the can becomes airborne

[runeman180]

how about the speed of 0 miles and 0 feet and 0 inches and 0 cm and 0 mm and 0 nanno meters and 0 angstroms per ever! (aka not moving at all :D)

[h0nk3yt0nk]

dogs gonna wag its tail to get this shit off... cant be silent

[AirDfdr04]

Speed should either be 0 (no movement, no sound).. or more than 333 m/sec 2 (speed of sound through air at MSL)

[peedabz02]

hahahaha!!! The question: what should be the speed? then its "zero mph" Its not stated there that the doG is moving or running...hahaha I love the accent!! hahaha

[visionaguilar]

Dogs doesn't like strings being attached to its tail, never mind its speed.

[captainobvious49]

the dog isnt moving?

[noxure]

If the dog accelerates fast enough and then starts running in a circle, the reactive force on the can will cause it to never hit the ground.

[jaihindhreddy]

Speed of thee dog must be above the speed of sound(i.e, 336m/s), Any dog cannot run at that speed. so it must not run. Hence the speed is 0

[STKhero]

take the string off the dog?

[mcdonaldman56]

I think the dog should be deaf.

[aliboulala65]

its a dog so he cant go 340m/s, so I thinkg the only possible solution is 0m/s

[frd4u1986]

Above 340m/s (Speed of the Sound)

[78brutal]

the speed of light................ that way the sound waves can't catch up to it and the dog hears nothing

[dragonoth87]

any speed it wants, the ground is a thick dirt and the dog is deaf

[ace41r]

Run faster than 340m/s ? or run around the can at any speed?

[choransword]

0m/s ? ftw lol

[bp56789]

Have a very short rope; >=0km/h

[Meylianny]

i depends..........whats the "ground" made of??

[Shayde1653]

oh and ive got a riddle or brain teaser, a dog was tied up to a 10 m rope and a bone was 15m away from the dog and the dog got the bone, how did the dog get the bone?

[0203304122]

@Shayde1653 The bone is 10 m (length of the leash) + 5m on the other side of whatever the leash is tied to.

(dog)-------10m---------(pole)­-5m-(bone)

[Shayde1653]

@0203304122 correct but there is another soloution the rope wasent tied to anything only the dog :P

[Shayde1653]

How the hell did i get from pingu parodes to this by only clinkin reccomendations O_O?

[tttc]

0 meters per second, or greater than 341 meters per second.

[myname12321]

0mph

or sonic speed

[g2fingers]

itz the easiest thing evr! 0 mph duh!

[jazzophis]

0 mph would work. that or get a 10000 ft string

[Toriaaa924]

@jazzophis oooppppss i meant to give you a point on your comment but accidentally marked you down sorry

[blunderbussify]

it has to shake off the can by clever manoeuvres.

how stupid is the answer, it might reach the speed of sound?

rather would it run around a black hole at speed of light to neutralize the gravity and have the can floating. but that would never work, if that can had contained any vegetable when it was in use, so there is no solution, because the question is unclear. what kind of can is it?

[Mace37]

The speed is irrelevant. The velocity is the only thing that matters in that as long as the dog is closer to the can than the length of the rope, it will not move.

Or if it was implied that speed meant velocity, then the string would have to be short enough that when hanging off the tail won't touch the ground.

[JKyWd]

faster than the speed of sound so that when the can does hit the floor the sound cant catch up to him and he cant hear it.

[blunderbussify]

yes, this is the boring answer

[SleepingHero]

Even if the dog was completely still, the can would still make sound because the string is tied to its tail - which I'm sure would be wagging.

I guess fast enough to keep the string taunt and the can parallel to the ground is good enough of an answer as any.

[blunderbussify]

he has to run really slow, because I dont think ear muffs will fit him so well

[fairyboy5311]

fast enough for it to stay in the air

[ron3358]

lol at 0:05 it souds like he says "AIDS" instead of "eight". so pretty much he says "I would like to give you my AIDS" lol

[blunderbussify]

gimme that AIDS, rofl :)

[tdasas11]

I have heard it too xD

[cod4TheDriver01]

hihihihi you're right

[pinoyhummingbird]

@ron3358 lol.

[rosstalbot]

@ron3358: How's your Russian? I'm sure Serguei could explain it with a more vernacular accent in Russian for you so there would be no ambiguity, but since you're struggling with English on an English language website, I guess that would be a waste of time too.

[bierbuik]

@rosstalbot wooow, get a load of captain bring-down...

[ron3358]

@rosstalbot

wow take a fucking joke.

[TTVFreeGraphics]

@ron3358 lol ;p

[wyattcon11]

there are 2 possible speeds, slightly faster than the speed of sound, or not moving at all

[simba00784]

0 mph.

(some people have written it can also be the speed of sound) but why? the dog, for example, could be moving at 100mph and the can would easily be in the air would it not? *however, upon thinking abou this, would the can stay in the air only when the dog is accelerating but when it reached 100mph and stop accelerating the can would hit the ground? or would the can stay in the air at 100 mph? im not sure

[saladf1ngers]

yeah when the dog stops accelerating and moves at a constant speed the can would drop back to the ground. Newton's second law Force = Mass x Acceleration

[rennie3915]

if he was running fast enough, air resistance would be acting against the can, the tension in the string would keep nearly perpendicular to the ground, whether the dog is accelerating or not

[paulmarko]

Yeah, the can would only drop after acceleration if the dog were in a vacuum. But then the dog would be dead. But I suppose the dog has special powers to be running that fast anyway. As long as we're making up properties of dogs, it's also a deaf dog so any speed would be ok.

[tharptown]

if the dog moves at 0mph, the can doesn't move. So there's no sound.

[Nocuras]

If we assume the dog cannot run at the speed of sound (doesn't need to be faster because the can is already behind it) then there's another solution. It just has to run fast enough to offset gravity (so the can is flying behind the dog like a kite)

[waketherabble]

Just have the dog walk in a circle around the can.

[nicenicole99]

hmm... a dog running faster than the speed of sound or light is impossible so... i think the dog can run at any rate as long as it is carrying the can with its mouth... if this is wrong... please tell me why... thx =3

[Freshoffdahoodbro]

the dog has to move faster than the speed of sound not the speed of light....

[nemoDaedalus]

Though of course technically since lightspeed > soundspeed, going faster than light automatically makes you go faster than sound as well.

But Einstein said you can't go faster than light, so that can't be the answer and I've yet to see a dog break the sound barrier (let alone light, even if it was possible!), practically both answers are incorrect.

[Tinnesa]

why, does it fear the can? then kill it, thats sick. :O

[drummerjc1995]

it has to run faster than the speed of light

[Nemesishk]

yeah this is the answer :))))))

[Zepplinne]

no, the answer is either

a. the dog is not moving

b. the dog is faster than the speed of sound

[drummerjc1995]

oh yea, i was ment to write sound oops

[drummerjc1995]

SOUND

[AlfredoHalo666]

walk around in circles

[MissAshia]

Duh too easy... the dog isnt moving!

[elitecssplayer]

wow, lmfao, I would have never guessed that!

[MissAshia]

hahaha=]]

[Dvalinor]

Sigh, the dog walks in a circle around the can - with any speed it wants. If you wanna be strict about it and say the rope would force the can to move even if it was a circular movement. Then fine! Let it be a spiral, twisting the rope around the can..

[BriDirt]

Too many possible answers for this. The dog for one could run 0mph, faster than the speed of sound, or run as fast as it wants in circles. Therefore the speed of the dog could be infinate.

[bLackpuppet]

lets just cut out the dogs ears and let it run as fast as it wants :D

[gfrggggg]

haha

[CuMeiLin]

hahaha you're funny :))

[wickman92]

Best answer ever

[BirthdayBasher13]

If the dog travels as fast as the speed of light then he wouldn't hear the can ( For awhile) because the speed of light is faster than the speed of sound.

Or the dogs not moving.

Or the dog chews the rope and runs away leaving the can to sit on the ground.

[sumc22]

the dog eats the can an dies, problem solved.

[stevendurr]

the speed should either be 0mph or fast enough for the air passing by the can to lift it

[CuMeiLin]

i agree :D

[matthew102000]

speed of the dog should either be faster than sound, or no speed at all.

[tdasas11]

he should stand in same place lol

[EighteenCharacters]

There are actually 5 solutions that I can think of.

1) As fast as he wants, so as long as it is back & forth or circular.

2) Fast enough that the can never touches the ground due to vector momentum.

3) Faster than the Speed of sound so that it never reaches him.

4) A possible 5 dimensional possibility with a remote chance of occurance

5) 0 thousand miles/hour.

[offlineallthetime]

look at the 2nd last comment

it says

0miles per hour

vorojtsov said that

[EighteenCharacters]

Heh... maybe I already knew that and I was just testing you :-)

Congradulations. You passed. I'm so very proud of you.

[yootubenewb]

As fast as the dog wants, I erased his ears, so he cannot hear the metal can. lol

[aapjesa]

1: dog goes back, takes the can and walks on

2: dog bits the string off

3: there is a hurricane so he won't hear the metal can

[nejtilsvampe]

funny thing is you have the right idea, he doesn't say anything about the dogs direction right? So the dog can run around in circles as fast as he wants without the metal moving.

[terrytibbs10]

0 mph

[eyepatchinc]

right! or he could run faster than the speed of sound & he wouldnt hear it... as if that were possible

[terrytibbs10]

oh yeah that 2! oh well!

[no1sjester]

The way I see it, there are 3 possible answers.

1) The dog is deaf.

2) The dog travels the speed of sound.. =/

3) The string falls off the dog... o_o

[fwackata]

it doesn't matter, the dog's deaf

[critter414]

IF he doesn't move it doesn't make a sound.

[raptriforcee]

Just move at the speed of sound.

[Wyvern97]

If the dog could go really fast, maybe the can would become like a kite or something lol

[supergal306]

0?

if he's not moving at all, he obviously won't hear it.

These are easy, and your kind of terrible at drawing metal cans...

[rmwaller]

And you're kind of terrible at spelling 'you're'. Hahahahhehheheheheheh....aahhh­hh.

[FCKEVRY1]

Use a rope that's a mile long. The dog can walk as slow as he wants. If the can moves, that means the dog's a mile away.

[FCKEVRY1]

Well it also depends on the hight of the building from which you throw the dog. As the dag and can reach their terminal velocity that will begin to rotate around their center of gravity. If you time it just right and make sure the dog hits the ground before the can, he shouldn't hear anything at all. So you see, it really isn't about speed. It's about timing.

[udownwithepic]

omg you made me laugh so hard thank you.

[FCKEVRY1]

WTF man? I worked hard on that solution!

[daos77]

How tights is the rope tied to the dog's tail? If you tie the rope extremely tight, the dog's speed can be any. He will be in so much pain, that he won't hear the noise the can makes.

[rom901]

LOL

[YummyBonBons]

he shouldn't be moving! no-one said he has to be moving!!

[beavsfano1]

the speed of the dog should be 0

or he could chew the rope off and do whatever he wants to do

[goodmanMD520]

the speed of sound so the sound will never reach him

[lolwutrawr]

Technically, you can't do this problem. No matter where you do this and/or what speed you go at, there will still be friction and thus, sound. The only place sound can't travel is in a vacuum.

[LordEyli]

uhhh, give the dog some spikey boots, and spill some sort of thick lubricant on the floor (and make sure there's nothing in the can), and there won't be a problem

or yeah, make the dog go so fast the can starts flying :)

[JulioJuliopolis]

Relative to the ground, the dog must maintain either a speed of 0 or whatever speed is required to generate and maintain enough lift on the can to keep it in the air. Since the exact weight and shape of the can is necessary to determine how much lift is required, I'll go with the first answer.

[ratava15]

Many possible answers to this brain teaser.

1. As fast as the dog wants as long as the rope is short enough not to allow the can to reach the ground.

2. As fast as the dog wants as long as the rope is long enough not to become taught and drag the can.

3. As fast as the dog wants so long that it is either deaf or unable to hear the dragging can eg:very strong wind.

4. Speed sound

5. Speed depends on aerodynamic properties of can (eg: getting a kite aloft)

6. run in circles

7. chew rope

[Davisdigi]

speed of light should work :P

[mikemcdonald113]

The same speed as a satellite in earths orbit, so that the can is in constant free-fall and never touches the ground.

[Lagrattouille]

Actually there are two awnsers ... But only one can be really accepted i guess.

Either it travels over the speed of sound >350 m/s or he doesnt move at all, 0 m/s

[abram730]

the can would stop dragging long before you passed the speed of sound... the drag of the air would lift the can.

I'll say zero as there are too many unknowns for another answer.

[daguyhuluvsvids]

err.....maybe just go fast enough untill the can just floats into the air?....or just let it hold the can in its mouth......dependz on the weight of da can

[chinw76]

If the dog was in grass, you wouldn't hear the can move since the grass would make a cushion for the can.

[goodmanMD520]

the speed of sound

[rockapellacocacola]

let the dog hold the can with its mouth

[jmsts91]

0mph

[HalfEatenDimSim]

How fast can a dog travel when thrown out of a plane?

[TThewsyo]

ah ha. i knew it. related videoes on this one. ericsurf6 is there he is another trickster. these two guys must be pals

[Fenikxpikx]

0m/s.

any kinetic energy given to the can will be converted to sound energy.

if the dog is at rest, the can is at rest too.

[fuse3214]

walk realllllllllllllllllllllllllll­y sloooooooooooooooooooooooooooo­w so it wont drag or just take the rope off :P

[yug001]

The dog can just put it in it's mouth so technically it doesn't even need to run. but if it needed to run then prolly..over 100 miles.

[barrella]

the speed of zound.

[wctje777]

totaly depends on wich way he is going lol if he moves to the can and back he can do that as fast as he can

[JolleTheDude13]

move so fast that the can does'nt hit the ground at all

[clockwise3559]

he shouldent move at all

[honse246]

if u go fast enough the can will not hit the ground at all

[datster739]

it *could* hold the can in it's mouth lol ~~'

[Sushiman06113]

its either the speed of sound or not moving at all

[ki6eki]

i just saw all these brain teasers back to back.. and they were ridiculously easy..

[jopeteus]

I think that they are easy too. But you still need to think few seconds.

[Cig187]

At the spped of sound ofcourse;)

But if can shouldn't also touch the ground then that dog should run at the Earth's escape speed (8 km/second)

[xylyze]

The dog won't hear the can if it running faster or on the speed of sound, or is standing still.

[jomomo]

ANY SPEED.

THE DOG IS DEAF!

[HowToUniverse]

ha,

[iChemicall]

lol

[seansbeckett]

judging by where on the can the string is tied, i bet there's a nonzero speed < speed of sound where it'd take off like a kite. If anything can, the can can.

incidentally, there's probably a speed at which the can can can can can along the ground, but it may need dance lessons first.

(yes, I'm sad)

[mariuszny]

the correct question is how many years in prison you will get for such cruel experiment.

[kobebryant0824]

LMAO!!

[havntthslightst]

None he is Russian, he gets promoted.

[polmeh]

I loled ;D

[john01524]

zero mph that way the can is silent

[ruiruivo83]

speed of sound

[danedaworld]

easy, as fast as it wants, pick up the can and walk with it =D pwned

or

ur already moving at a speed cus earth is revolving at over 66k mph so u already have the speed lol but if the world stops...whoooosh

[rocioarturodiana]

his vose is so sleepy o am sleepy

[russiaboy12321]

0km

[lisamariefan]

I'm gonna go out on a limb and say a speed of zero.

[gandolfcom]

A dog would likely smell the food that was in the can and pick it up and carry it.

Or...

Assuming the dog rides in the cab, the speed of it's owner's pick-up truck.

[ricardogarza8]

I agree...lol

[Sale15]

it's based on the mass of the dog, if the mass of the dog and the can are similar then the amount of static friction from the can to get it moving determines the same acceleration

used for that force. You may then determine its speed by the approximate length of the cord.

[OtacDomovine]

300 000.00000000000000000000000000­1 km/h

:P ^^

[Kenjineering]

1) 0 km/h

2) >speed of sound.

3) In Outer space. any speed

4) an epic can that is filled with lighter than air gas, with a volume that makes it float off the ground but doesnt lift the dog with it. therefore any speed.

5) A ridiculously looooonng rope in the order of 4 km. therefore, anyspeed..

[hodor]

1)b) Dog run in circle (radius smaller length of the rope)

6) ridiculously short rope/ridiculously tall dog

7) poor dog is deaf?

8) Ambient noise greater than what the can can make.

9) The ground is grass, carpet, ... ?

[Kenjineering]

HAAHAAA good suggestions!

[dgunchev]

I knew this wit a cat... We never thought about running it in circles. Great ideas!

[yahoopig]

Just fast enough for the can to leave the floor. about 100 mph do it

[Kenjineering]

AHAHAHAHHA!

If the dog runs faster then the speed of sound, it could still hear the can through the rope if the can is making a noise. It could also hear the can through the air if there were enough drag so that the speed difference between air and dog is less then the