In the fourth century BC, the entire Attic fleet was delayed just because a soldier sneezed
The Greeks were very superstitious.
Cannes
We went to Cannes this weekend for the Cannes Film Festival. Cannes is in the south of France, right next to Monaco and Nice.
It's on what they call the the Côte d'Azur (the Blue Coast), or the French Riviera.
A lot of celebrities go to this festival. It's pretty fancy, and a lot of normal people dress up and pretend to be important. I played the part by wearing my favorite shoes.
I didn't take this picture, but they were there.
Here is the red carpet. It's a lot less impressive empty, but it's nearly impossible to get close enough when it's full.
Cannes is tropical. It felt good to be in some humidity for once.
Out of curiosity, I looked up the draft of this boat. It towers more than 200 feet over the water, while it's lowest point is only 29 feet under water. This is crazy to me, but it makes sense, I guess, given how wide it is -- 133 feet.
Our airbnb was in the basement of a French family's house, just up the hill from the beach.
Tolu is writing a book -- that's pretty cool.
Despite all efforts, I got sunburned. They ought to call it 'radiation burn,' because that's what it really is, and people would be more inclined to protect themselves if it was called something scary.
My favorite thing we did was go to the beach screenings on Thursday and Friday night. They showed Boyz n the Hood, which was phenomenal, and Le Patriot, which was an exercise in French listening.
The atmosphere was dream like.
We all know and love the Jet d'Eau for obvious reasons. You're lying if you say you've never asked yourself this question:
Will the Jet d'Eau actually rip my arm off?
Well, we did some calculations.
Click here to skip the physics.
To start, we know that the Jet d'Eau is really tall. Specifically, we know that it shoots water to a maximum height of 140 meters, $$h = 140 m $$.
We also know, if we neglect air resistance and water interactions, that energy is conserved. Therefore the total energy is equal to the water's potential energy plus its kinetic energy:
$$ E_{tot} = PE + KE$$, where $$ PE = mgh $$ and $$ KE = \frac{1}{2}mv^2$$
The water comes out of the Jet d'Eau fast, but immediately begins slowing down because of gravity, and at the top, it stops moving altogether. We can then say that at the top, the water has no kinetic energy -- it's all gravitational potential energy -- and thus $$ E_{top} = PE = mgh $$.
Similarly, since we have defined the bottom of the Jet d'Eau to be $$h = 0$$, the water has no potential energy there. We can then also say $$ E_{bottom} = KE = \frac{1}{2}mv^2 $$. Since energy is conserved, the energy of the water at the top of the Jet d'Eau must be the same as the energy of the water at the bottom of the Jet d'Eau. Therefore
$$ E_{top} = E_{bottom} = mgh = \frac{1}{2}mv^2 $$
We can solve this equation for the velocity of the water at the nozzle of the Jet d'Eau: $$ v = \sqrt{2gh} $$ This comes out to be about 52 m/s, or 116 mph. Not slow.
Next we want to find how much water comes out in a single time interval. This is called flow rate ($$Q$$) and it's defined as the area of the nozzle times the velocity of the water: $$Q = Av $$. Since the nozzle is a circle, its area is $$A = \pi R^2 $$, where R is the radius of the nozzle. And since we already know $$v$$, the flow rate of water out of the Jet d'Eau is $$ Q = \pi R^2 \sqrt{2gh} $$ m^3/s.
Now we will make the assumption that the stream of water is just a bunch of small, sphere shaped drops of water. To be more accurate, we'll say that they're really small, such that their radii are only 5 mm, $$ r = 5 \times 10^{-3} m$$. If we divide the flow rate by the volume of one drop, $$V_{drop}$$, we will get the amount of drops that are spewed out by the Jet d'Eau every second ($$n_{drops}$$). Once again, the drops are spheres, so their volumes are $$V_{drop} = \frac{4}{3} \pi r^3 $$ m^3.
$$n_{drops} = \frac{Q}{V_{drop}} = \frac{\pi R^2 \sqrt{2gh} }{ \frac{4}{3} \pi r^3} $$, and simplifying: $$\frac{3 \sqrt{2gh} R^2}{4 r^2} $$ drops/second come out of the Jet d'Eau. Now we want to find the force each drop will exert on you arm.
We know that $$ F = ma $$ (thanks Newton), and that $$ a = \frac{v}{t} $$. If we assume the pump of the Jet d'Eau has 0.25 seconds to accelerate the water before it comes out of the nozzle, then $$a$$ is simply $$a = 4 \sqrt{2gh} $$ m/s^2. Mass can be expressed as density times volume, like this: $$ m = \rho V $$, so the force of one drop is $$ F_{drop} = ma = \rho V a = \frac{16}{3} \rho \pi r^3 \sqrt{2gh} $$ N/drop (Thats N for Newtons because we like Newtons).
We already know how many drops come out of the Jet d'Eau every second, so if we assume your arm is in the Jet d'Eau for 1/10 second before it's ripped off (or not), then we can multiply the number of drops per second by the force of each drop divided by 10:
$$ F_{total} = \frac{F_{drop} n_{drops}}{10} = \frac{(\frac{16}{3} \rho \pi r^3 \sqrt{2gh}) (\frac{\pi R^2 \sqrt{2gh} }{ \frac{4}{3} \pi r^3})}{10} = \frac{4}{5} \pi R^2 \rho g h $$
This is neat, because it doesn't matter how big the drops are after all. It's also neat because, with the nozzle radius $$ R = 0.05$$ m and water density $$ 10^3 \frac{kg}{m^3} $$, the force on your arm comes out to be 8,629 N, which is more than 160 psi. That's some serious pressure, and if we had considered air resistance and water interactions, it would be even higher.
Will it actually take off your arm?
If you were somehow able to get your arm entirely into the Jet d'Eau, it would at least cause some damage. It's tough to say for certain how much damage without some experiments, but I'm not about to try it, so we may never really know.
A good follow up question is: How far would the Jet d'Eau launch a person if they jumped into it? Come back next week for the answer.
Nice : was it nice?
Ha!
It was!
They don't have any sand Nice. It's only rocks.
But they aren't sharp and uncomfortable like you might think. They're soft, old rocks, and if you do it just right it feels kind of like a massage when you lay down.
Michael was still dressed for Cannes when he showed up in Nice.
This statue of Apollo has apparently been quite controversial here. This is because he's 4 times the size of a normal human. Consequently, each part of him is 4 times the size of a normal human. In the 70s he was actually taken out and replaced with a tree, and before that he was covered with grape leaves. But now, in all of his glory, he's back.
Michael loves to do stuff like this, and he usually succeeds.
I stayed in a hostel on Saturday night, and hung out with some Australians who were in France for the Indy 500 race in Monaco.
I accidentally ordered boeuf tartare, which, if you didn't know (I didn't), is literally raw beef. It was a cultural experience to say the least, but as of writing this I have not shown any signs of Salmonellas.
The Geneva Open
I got to watch some quality clay court tennis earlier this week. There was an ATP 250 tournament held in the park not a mile from our residence.
I got a picture with, Alexander Zverev, the guy who went on to win the tournament.
Our conversation went something like this: "So are you going to win this tournament?" "I hope so." "You know my name is Alexander, too?" "Oh really?" "Yeah, so you're only the second best Alexander."
I don't think he got it because he mumbled some excuse and escaped, but oh well, I tried.
Another great week in the books.