Archimedes' Principle

[krzie18]

i showed this to my science teacher. he loved it!

[nnesguerra02]

in archimedes' time, the king ordered someone to make a crown from a brick of gold. then the crown is made and when they check it, the mass of a standard brick of gold is equal to the mass of the crown. but archimedes doubt that the crown is not made of pure gold. in the end, he placed both objects, the brick and the crown, in a container with the same amount of water. the crown displaces more water than the gold. i thought that the mass of an object is equal to the mass of water displaced.

[codewalters]

Excellent lessons !!!

[santoshdc100]

Thank you for adding this video !!!!!!!

[0x96C]

Cool! Thanks for this upload.

[UniversalVision]

Ah. So and the significance of the name Archimedes makes this ever so relevant.

But I gotta say this is though basic chemistry, its applications are useful when extended to nautical engineering. Also, I have to admit that I came across this video after watching "Meet the Medic", which have no relevance to science but in particular mad science! LOL! And video games.

[silenthorsewhisperer]

This can be used to show how full scale boat lifts (with water in them) work even if the lifting ram is just in the centre and the boat moves. Great physics - keep up the good work!

[silenthorsewhisperer]

Great video! As will all physics just doing the maths is not enough! It would be good if it explained why the water is displaced and the block sinks in to a certain depth! Some understanding of pressure and particle motion is required. I will give you all an example to demonstrate - if you hang a rectangular tank half full of water from its midpoint (over the centre of mass) and place a floating boat in the tank - even if it (gently) moves to the left or right the tank does not tip....

[ugotmeggedhardcore]

I'm in grade 8, and i have a test coming up about this. but it was too much info, but fun to learn! i totally get it, and now im ready! thanks!

[canadianslang]

good and well detailed video, this helped me with my project thanks!

[babblingmonster1802]

that horse is overweight....

[becurbilyg]

this is the wealth of Greece!

[flunerClay]

Please make more explaining videos abaut physics (mechanics).

[Xukhruff]

weight of the body immersed in water=buoyant force...then y do some objects

(like needles n paper etc) sink in water??they should remain in equilibrium if their weight=buoyant force.......

[qwerty2000000]

this guys voice is so relaxing lol

[jimbisonlinenow]

Which direction would a helium filled ballon travel inside the space shuttle?

[cycon666]

this sooo helped me on my homework

[ngirlrock]

thank you, youtube, for doing my homework for me :)

[seattleunited]

THE BEST VIDEO EVER! THANK YOU SO MUCH!

[kengyingying]

In fact, i'm not understand this pirinciple thoroughly.

My question: The actual weight of an object is 12N. The apparent weight of the object when it is immersed in water is 9N. What is the density of the object?

Can anyone help me to solve this question??? Thanks.

[4JWM]

great video

[gilliantje]

Now i understand it, very good vid. Thanks

[minsatminsat]

i don't get it-shudn't the weight of displaced fluid, when you put the stone on the block, be equal to the sum of the weights of block and the stone? how come the weight of displaced fluid equal to just the weight of the stone?

[r0naldinh010]

i no 1 part of my exam im not failing...

[sanwihuelin]

Horray!

Varias veces después de haberlo llevado en la escuela, finalmente lo he comprendido..

[TheAviationArt]

Great Vid. Thanks a lot. It helps.

[powercord123456]

but why if only half the block is submerged the full weight is displaced

[bubbliejock]

Block has a force down called weight.

The weight of the "displaced" water must equal the block for it to float. The displaced water is effectively pushing against the block to retain the space from which it was displaced. This results inan upwardly force called buoyancy.

As the block is much less dense than the water then only part of the box will sink ie the volume of the block which equals the same weight as the water.

Example

water = 1g/cm3

box 0.25g/cm3

1/4of the block will sink

[Exception88]

Because the block is less dense than the water it sits in.

Density = Mass/Volume

Thus, Mass=Density(Volume).

The weight of the volume of water displaced by the block equals the weight of the block. Since the block is less dense than the water a smaller volume of water has more mass than an equal volume of the block. Since only half the block submerged this suggests that the block is half as dense as the water.

[darknidevle89]

Bravo!

[meedoselecao]

Fantastic vid .. thts wonderful !

[tobby2468]

prety good

[engpolo1]

that`s great

thanx

[mandassux]

thanks!!

[Maartenn100]

You gave me the image of the clever grandpa or uncle I always wanted to have who fascinates his grandchildren, nephews and nieces about the basic laws of nature, the stars, etc... With a reliable knowledge where even their teachers in school can have a lesson from... And that impression is great!!

Your (grand)children, if you have them, are blessed with such a teacher in life.

[darksideofthebrick13]

very informative. great video.

[clownstangler]

cool vids, thank you

[Rowe2597]

thats awesome.....

[Brutalexecution]

Thanks man. Nice video

[Jiosonus]

I love these videos. You learn more with these than sitting in a classroom sometimes. I wish all science was like this.

[Thymonico]

I did it!! I'm best, I'm genius! Or... I guess it wasn't that hard... ;)

Great video, Hilaroad!

[victorscope]

Thank you very much for the videos. I hope you continue posting. They help to fuel my newfound interest in science and motivate me to learn more.

[jonce81]

Great Videos...

[RestauranteChines]

nice

[heratioalundi]

what happens when you have two cubes of the same volume but different density that completely sink ?

A brick of iron in that tub will displace the same amount of water as a brick of gold, even though their density is different, when both are at the bottom of the tub.

Seams to only work with floating object, or using floating object as a pressure pad.

How would you measure the density of a cube of gold while a cube of iron will sink just as well? By placing it on a piece of wood?

[ScienceOnline]

The buoyant force acting on an object completely submerged in water equals the weight of the displaced water. In this example the volume of the displaced water equals the volume of the brick.

Both the gold and iron bricks will experience the same buoyant force (assuming they are the same volume). The net force down (force of gravity - buoyant force) acting on the gold block will be greater because it is denser, therefore heavier, then the iron brick). .....

[ScienceOnline]

Placing the brick on floating wood displaces a weight of water equal to the weight of the brick.

[heratioalundi]

"The buoyant force acting on an object completely submerged in water equals the weight of the displaced water."

if i had both a solid iron brick and a hollow thin shell brick (with air inside) both of the same volume, would they experience the same buoyant force when completely submerged?

[ScienceOnline]

Yes, but you might have to push and hold the hollow one under water. This happens when the buoyant force exceeds the weight of the object.

[timonczesq]

AFAIK, the buoyant force would be the same. Although the hollow thin shell brick requires much less force to push it upwards (therefore it floats). You need to manually sink it and then it will push the required amount of water (as presented in the video).

[heratioalundi]

theoretically, will an evacuated balloon (vacuum inside) rise? (if the evacuated space is light an rigid to preserve its volume and not be crashed)

What about a balloon filled with the same composition and temperature of plasma as in the upper layers of the ionosphere(rather then hot air) will it rise? and if it does will it reach the ionosphere?

[timonczesq]

Assuming that a balloon would survive such flight, it would rise as long as its mass would be less than the mass of the particles it displaces around (for example: air in the lower atmosphere). It would reach equilibrium at some height and then stop rising. The substance it's filled with would only affect its final height (with vacuum giving the best result). Hard to tell right away what composition would give what final height, but you get the idea, I hope ^^

[heratioalundi]

yes i do, thanks :)

hmm, vacuum balloon..... is it even tangible?

(its also a bit confusing at first glance because vacuum is low pressure while hot air is high pressure, so in one case we heat air and in the other we evacuate it. although vacuum is matter that is very far apart it doesn't have the pressure inside that a heated gas does right? so is it even similar in principle? i mean super hot, super low density high pressure gas vs vacuum.

[timonczesq]

It's not the pressure inside balloon that makes it fly, but its overall mass that displaces air. Making something inside of a balloon (usually a gas) hotter just means that its density will decrease thus reducing the mass of the interior. The balloon with vacuum inside was only an example (it would inflate). But the point is that the buoyancy is dependent on the mass inside a container. It's explained here: en . wikipedia . org/wiki/Buoyancy#Density (remove all 4 spaces between the 2 dots).

[timonczesq]

It would DEFLATE, I meant.

[heratioalundi]

so how do i make a vacuum balloon float and rise? if i just took a regular balloon and evacuated it with a vacuum pump it would not rise, it will shrink like a resin because the outside pressure is so much greater right? would it help if i evacuated some kind of a reinforced balloon that would attempt to hold its walls from structural collapse like a glass flask but much lighter. any ideas on how to make a vacuum balloon that rises at least a bit?

[timonczesq]

You need a material that will preserve its volume when evacuated. And this is a broad topic of material science. You would need a material strong enough to sustain high vacuum volume and light enough to actually float. Google for "vacuum balloon" - it gives some interesting links.

[timonczesq]

What this method measures is the VOLUME. You calculate mass by multiplying volume and density. Two different bricks of metal may have the same volume (and this method will show it) despite that they might have different densities (and therefore different masses).

[M3n747]

As always, I greatly enjoyed your video.

[vissvienna]

It would've been great having these videos when I was in school back in the 80's!!

Another great video.

[Demoman42]

Please post more vids on Youtube! Thank You!

[BryanBeatsYouAll]

MIND=BLOWN

[crxracer420]

i got 1544.08 POUNDS

that was cool.

[sctrep]

!!!!

[LordMonSeigneur]

oh and thx for the vid , realy interesting like always :D

[Peacenik]

thats a big horse!

[shadowhunter45s]

Not Really ud be surprised how much a horse weighs

[lmeister3]

lol that's not a big horse

[leolava]

THANKS <3

Love ScienceOnline.

[lejink]

loved it, thx again !

[RDJim]

1,600 lbs?

[LordMonSeigneur]

yup 1587 lbs

[DeaconSwayne]

Very good!

[xazuross]

I love these videos :D