The real story behind Archimedes’ Eureka! - Armand D'Angour - video Dailymotion

TED-Ed

When you think of Archimedes’ Eureka moment, you probably imagine a man in a bathtub, right? As it turns out, there's much more to the story. Armand D'Angour tells the story of Archimedes' biggest assignment -- an enormous floating palace commissioned by a king -- that helped him find Eureka.  Lesson by Armand D'Angour, animation by Zedem Media.

Transcript

00:00Archimedes' Eureka Moment

00:10When you think of Archimedes' Eureka Moment,

00:13you probably think of this.

00:15As it turns out, it may have been more like this.

00:19In the third century BC,

00:21Hieron, king of the Sicilian city of Syracuse,

00:25chose Archimedes to supervise an engineering project

00:28of unprecedented scale.

00:30Hieron commissioned a sailing vessel 50 times bigger

00:34than a standard ancient warship.

00:36Named the Syracusea after his city,

00:39Hieron wanted to construct the largest ship ever,

00:42which was destined to be given as a present for Egypt's ruler, Ptolemy.

00:47But could a boat the size of a palace possibly float?

00:51In Archimedes' day, no one had attempted anything like this.

00:55It was like asking, can a mountain fly?

00:58King Hieron had a lot riding on that question.

01:01Hundreds of workmen were to labor for years on constructing the Syracusea

01:06out of beams of pine and fir from Mount Etna,

01:09ropes from hemp grown in Spain, and pitch from France.

01:13The top deck, on which eight watchtowers were to stand,

01:17was to be supported not by columns,

01:19but by vast wooden images of Atlas, holding the world on his shoulders.

01:25On the ship's bow, a massive catapult would be able to fire 180-pound stone missiles.

01:33For the enjoyment of its passengers, the ship was to feature a flower-lined promenade,

01:38a sheltered swimming pool, and bathhouse with heated water,

01:42a library filled with books and statues,

01:45a temple to the goddess Aphrodite, and a gymnasium.

01:51And just to make things more difficult for Archimedes,

01:54Hieron intended to pack the vessel full of cargo.

01:58400 tons of grain, 10,000 jars of pickled fish,

02:0374 tons of drinking water, and 600 tons of wool.

02:09It would've carried well over 1,000 people on board, including 600 soldiers.

02:15And it housed 20 horses in separate stalls.

02:19To build something of this scale only for that to sink on its maiden voyage,

02:24well, let's just say that failure wouldn't have been a pleasant option for Archimedes.

02:29So he took on the problem.

02:31Will it sink?

02:32Perhaps he was sitting in the bathhouse one day,

02:35wondering how a heavy bathtub can float,

02:38when inspiration came to him.

02:40An object partially immersed in a fluid

02:43is buoyed up by a force equal to the weight of the fluid displaced by the object.

02:49In other words, if a 2,000 ton Syracusea displaced exactly 2,000 tons of water,

02:55it would just barely float.

02:58If it displaced 4,000 tons of water, it would float with no problem.

03:02Of course, if it only displaced 1,000 tons of water,

03:06well, Hieron wouldn't be too happy.

03:09This is the law of buoyancy,

03:12and engineers still call it Archimedes' principle.

03:15It explains why a steel supertanker can float as easily as a wooden rowboat,

03:20or a bathtub.

03:22If the weight of water displaced by the vessel below the keel

03:25is equivalent to the vessel's weight,

03:27whatever is above the keel will remain afloat above the waterline.

03:31This sounds a lot like another story involving Archimedes and a bathtub,

03:36and it's possible that's because they're actually the same story,

03:39twisted by the vagaries of history.

03:41The classical story of Archimedes' Eureka and subsequent streak through the streets

03:46centers around a crown, or corona in Latin.

03:50At the core of the Syracusea story is a keel, or coronae in Greek.

03:56Could one have been mixed up for the other?

03:58We may never know.

03:59On the day the Syracusea arrived in Egypt on its first and only voyage,

04:04we can only imagine how residents of Alexandria thronged the harbor

04:09to marvel at the arrival of this majestic floating castle.

04:13This extraordinary vessel was the titanic of the ancient world,

04:18except without the sinking, thanks to our pal Archimedes.

04:23The

The real story behind Archimedes’ Eureka! - Armand D'Angour

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