Physics&Sailing

Do you know what’s cool? Aerogels. Do you know why? Cause you can do so many things with them, they are so useful and have so huge potential. I think this might be one of the things I will be very interested into. Here are some quick facts about them.

Aerogel was first produced in 1931 by Samuel Kistler as a result of bet with his colleague Charles Learned. They bet that dr Kistler won’t be able to remove all the liquid from jelly (same as the one you can eat) without affecting the solid structure. It was interesting because jellies are neither completely solid structures or liquid, they have a nanoscaled skeleton that is solid and rest of it is liquid. They didn’t know how will it end up.

He solved out the problem and achieved in a result thing that is now called the aerogel. He did it by putting it to the high pressure vessel called an autoclave, and heated up to the point called critical of the liquid (point where liquid and gas can coexist and cannot be distinguished) and then depressurised it, so all liquid vaporized and only solid structure of the body left.The skeleton that is left after such process is just 1% the mass of what was before. 

Aerogel is great thermal insulator. It is because of two facts: first- it is 99% made of air, which is very good thermal insulator, and second- its structure. It’s because the width of the pores is smaller than the air particles travel on average between colliding with each other. So for a high-energy particle (hot one) it is very difficult to pass the labyrinth of nanostructures of the aerogel. If we’ve got a aerogel brick and we heat it from the bottom, it will be for a very long time cool at the top. Air particles get hot at the bottom, but can’t transfer the energy to the ones at the top (not that easily).

Also it is very light. VERY. 1 cubic meter of aerogel weighs 1,5kg. Mass of 1 cubic meter of water is 1000 kg.

Aerogels can have different properties depending on what do we combine them with. They can be waterproof, soft, stiff, bending and whatever chemistry allows us to do with them. For now that is all about aerogels. I am sure I will post about them few more times. I hope I will be able to understand more complex facts about them. 

Lately, I had on my physics classes thermodynamics. In a nutshell: thermodynamics is a branch of physics which deals with heat and temperature and their relation with energy, work, radiation and properties of matter (source: Wikipedia). At High School level, second law of thermodynamics, which is nota bene one of the most important laws in physics, is explained with the engine efficiency, more precisely: the Carnot Cycle. Carnot Cycle is an idea first proposed in 1824 by French physicist Sadi Carnot, of the thermodynamic cycle with the highest possible efficiency; when heat is converted into work; e.g. when gasoline is burnt into “power” in your car. Basically, you can never convert all of the energy you put into any kind of engine into useful work, what means, that always some of fuel will be lost in some form of energy (most often: heat). Now imagine: you tank your car with 50 liters of diesel, approximately 20 to 25 liters is lost! In spite of that diesel engines are the most efficient engines used practically. Back to Carnot, efficiency of engine he came up with has a definition 

W- work done by the system

Qh- heat put into system

Tc - absolute temperature of the cold reservoir

Th- temperature of the hot reservoir

It is theoretical because it is much more complicated in practice to create one. At school we assume all gases are ideal, as we know, nothing is ideal in real life. I will not try to explain why exactly it can’t be achieved, but I will leave a link to articles where it is explained. 

https://www.sciencedirect.com/topics/engineering/carnot-cycle

But why (theoretically) it is impossible to convert all energy put into energy out in a cycle? Because there wouldn’t be any energy to sustain it, simply the engine would stop and it would be senseless to have a one-cycled engine. It would have to be started over and over, which means, putting more and more energy.

It is astonishing how much energy is lost all the time (that is why I’d rather like to lose green energy than fuels). But we can’t really do anything about that. Also because of that energy loss, perpetuum mobile would never work. Even if some devices look like they could spin, move or something like that (because many of perpetuum mobile ideas are based on e.g. spinning circle with weights) they will never do it eternally. I wanted to put a gif with it but I ca

I am back from my cruise and I must say, it was the best thing I’ve ever done! I can’t compare it to anything else, sailing for 4-5 days on the same tack, all you see is ocean around you, no contact with the world, being tired most of the time. It took us two weeks, we had short stop on the Azores, so I was 10 days on sea without any break. That was something new. I saw dolphins, whale, pretty big waves, perfectly clear sky with plenty of stars and something what made me very curious: luminescent plankton.

 During the night, when waves hit our boat and water was spilling all over the deck you could see very small, gleaming points. At first I thought that I have something wrong with my eyes, but then it turned out it was simply plankton. When I came back home I checked why was it gleaming. And the answer is: to defend. But wait, how light can defend you? Apparently, it is possible. When a plankton is disturbed by moving it, it produces light through chemical reactions taking place within its body known as bioluminescence (bioluminescence is common in nature, e.g. fireflies). The bioluminescence results from a light-producing chemical reaction also called chemiluminescence. Certain types of chemicals when mixed together produce energy which ‘excites’ other particles on vibration and generate light which causes the glow. The light has two purposes: the first one is to scare a potential fish that could eat the plankton, and the second one is to attract some other predator, that would eat the fish.  There’s always a bigger fish ;) 

Not only Richard Feynman was one of the most prominent physicists we know, but also he had natural ability to share his knowledge, you can find out about that by watching lecturers below. Additionally, he was extraordinarily interesting person in private life. I recommend his autobiography titled: „Surely You're Joking, Mr. Feynman!”

In this post, I will describe how breeze works and about what we need to remember. I will try to extend it, so more physics is described ;)

Sun radiation mostly warms up the earth’s surface. Gases in the atmosphere don’t interact with the sun’s radiation that much. Our atmosphere is heated by earth’s surface with conduction. Let’s say we have a very hot day and we are on a beach. Sand is burning our feet, but the water in the sea is rather cold. When the earth is hot the air above it is also hot. When a temperature of a gas increases, volume increases as well. The air goes up, pressure decreases and a colder, more dense air from above the sea, where pressure is higher, fly into the place where is low pressure. It is called a sea breeze. Nothing complicated, but we need to keep in mind that sometimes some factors may make it impossible to come. A year ago I was in Barcelona where we had World’s Championships. For three days (of 5!) there was no wind, even though it was hot, no clouds were above us, the sea was colder. However only once a sea breeze came. Why was that? A massive influence on air’s circulation has terrain which in Barcelona is rather mountainous which may cause problems to breeze built.

Conditions required for the breeze to come: - the terrain must be heated to the temperature higher than the sea temperature - light land wind is necessary (beneath 15 knots) - convection is needed in the form of building cumulus clouds

Last week, everyone was talking about the first image of a black hole. It’s impressing, I must say, but scientists could have pretty precisely predicted how would it look like. I extended my knowledge about this black hole after I saw it, so here are some facts about the M87:

-  It is in the core of Messier87 Galaxy, which is 4900 light years away from Earth

- It is a supermassive black hole, its mass is approximately 6 000 000 000 mass of the Sun

- Maximum diameter is about 25 000 AU (AU- an astronomical unit which is an average distance from Sun to Earth)

A black hole is a spacetime region with such strong gravitation that nothing can escape from it. It means that no object, particle or wave can escape from it. The boundary after which nothing can escape is called an event horizon. Black holes form from collapsed very massive stars also they can consist only with three physical properties: mass, charge and angular momentum.

I’m going to answer a few questions you may ask yourselves about this picture. First of all, one side is brighter than the other, it’s because of relativistic beaming. The matter is moving in some direction, when it’s going away from us, the wavelength of light is longer, and when toward’s us- shorter. The matter is going very fast (with a significant fraction of speed of light), so differences in wavelengths are observable. That is why the colour is not the same everywhere. Also, it has a very high temperature (millions of degrees), so it's luminating. The picture was taken by electromagnetic telescopes from all around the world. The spacetime around the black hole is so curved, that light which initially heads in some direction might turn 180 degrees and travel somewhere else. It is because of a powerful gravitational field. Also, this photo proves, once again, Einstein’s theory of relativity.

My dad asked me, whether this black hole was so huge, would it someday “gobble down” the whole universe. The answer is no. As the mass of a black hole before and after its inception stays pretty much the same all object orbiting around it does not change. The force of gravity is the same, the centripetal force doesn’t change, no other forces start to act. The other reason why it wouldn’t destroy the universe we know is because of its expansion. Edwin Hubble first noticed that the universe is unceasingly expanding. Any black hole couldn’t “eat” all the universe, because it wouldn’t reach it. According to Hubble’s law, the further an object in the universe is, the faster it's moving away from you.

I have something to announce! On next Monday (15.04.2019) I am going to St. Maarten, where I will be joining Sailing Poland and crossing with them Atlantic Ocean, finishing in Vigo, Spain. The boat I will be sailing on is ex-team Mapfre Volvo Ocean 65 (picture below), from the 2015-2016 Volvo Ocean Race edition! I must say, I am more than excited about that. I won’t have access to the internet during this cruise. Furthermore, I don’t exactly know for how long will it last (it is said, that approximately two weeks). According to World Sailing rules, I am officially taken as a PRO on that boat (but it’s considered mostly during regatta).

I thought it might be a nice idea to write about Coriolis effect and a bit more about meteorology in general in this and next post, as both are highly significant during sailing, especially on open waters. To begin with, I think most of the people heard, that water in the toilet spins the other way round on different hemispheres, and this is due to the Coriolis effect. But this is a myth and Coriolis effect, unfortunately, cannot be observed on such a small scale and in such short period of time. But how does Coriolis effect work? We need to remember it is just an effect, it’s not a law, it doesn’t bring anything new, it just explains why something happens, referring to actual laws (like in this case, Newton’s laws). We may come across with Coriolis force, but just like centrifugal force it is a pseudo/apparent force, which means it is some kind of simplification of another force or forces, so it can be substituted and explained by them. Basically, everything here is about movement and different speeds in different points. For instance, on equator air has greater speed than on higher/lower latitudes. That air has greater momentum. Air moves, when air with higher speed (and momentum) moves to the area where air has lower speed, it “outruns” it, and from earth’s point of reference, its path of faster air is curved. The same with air with low speed, as it moves to “fast air” area, it seems to be curving. To me, personally, it is very hard to picture it, so I will put a link to short video, where it is perfectly explained and shown, why water in toilets doesn’t care about Coriolis effect, and how it exactly works.

The reason why they are so fast is due to many factors, but generally speaking it is about their construction and the way how they make us of a phenomenon called apparent wind. It is a sum of true wind and head wind vectors. Head wind you can experience while riding a bike, it’s always blowing straight in your face. True wind is caused by motion of air particles due to differences in pressure. Apparent wind is always something in between. This is interesting, because apparent wind allows boat to sail faster than the speed of true wind. For instance AC72 top speed was 44 knots, while the wind speed was 16 knots! A picture below shows how vectors are summed. Basically, when you are sailing you need to adjust your sails not to the true, but to the apparent wind.

My name is Oskar Niemira. I am 18 years old, I am from Poland and I’ve got two main passions: sailing and physics. And I’d love to combine them. But why am I writing that? Because I want to share it to others. How am I going to do that? By adding here what I know, what I have just learnt and what I don’t know yet. How will it look like? I’ll be telling my sailing story and trying to explain where is physics behind it.

The very first boat I had contact with, was the Optimist. It is a small boat, with one small sail for   children. I started learining how to sail on it at the age of 9. And I loved it! It seemed fast and scary, I was terrified when more than 15 knots were blowing. I had no idea how others were able to sail so fast, while I was hardly moving. And, obviously, a lot of physics applied there, of which I didn’t even try to think. I, like most of the children, didn’t try to figure out why by putting a daggerboard in, the boat was moving in a straight line or why a sail had to be in this particular setting. But now I do.

Let’s start from basics. The fact that a boat is moving in any direction is due to wind and a lift force, that is exerted on boat’s sail(s). This is both the first and the second force acting on a boat: lift. Because lift is also generated under the boat, by keel. Any sort of keel, like simple daggerboard is resposible for the lift force. But what is that lift force? Just like in plains, lift is generated due to Bernoulli’s princpile and Newton’s laws. When a water flows around keel (as the boat is moving), on the two different sides of it the water speed is different. Precisely, on the windward it is moving faster than on a leeward. This means, that (and here’s the Bernoulli’s principle) on windward side of a keel pressure is lower. Furthermore, waterflow because of keel, changes its direction. According to Newton’s second law, this change in flow direction requires a force applied to the water by the keel. Then Newton’s third law requires the water to exert an  force on the keel, thus a reaction force, lift, is generated opposite to the directional change. How sails work can by explained by all of above as well. Analogy is the same.

This is my first post here. On this blog many things I will be writing will be certainly new to me, some of them I might not understand completly or properly at first, however I will try to do my best and share my knowledge in approachable way.