Phys-X

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Shadoof

Anybody even slightly interested in science and technology will have heard of a relatively new space company called Space-X. They are very close to launching yet another craft into space set currently for Jan 14th. But, one of their most memorable accomplishments, for me at least, is when they had a Falcon 9 rocket land on an autonomous barge that was floating in the Atlantic Ocean. The physics and calculations that had to be done before hand, and during, had to be crazy. The team at Space-X would have had to write programs for the rocket and the ship to be able to talk to each other, they had to have very precise GPS to put the rocket in the same place as the ship. Other things they had to account for is that the ocean is wavy and the barge would be moving all over the place, they had to make the barge be very stable and still, making it move to directly under the rocket. To make sure that the rocket didn't have too much speed as it touched down on the barge they had to program for a very precise 'suicide burn' that would stop any lateral movement and greatly reduce the vertical movement. All of these physics calculations came into a very amazing and groundbreaking landing. Hopefully Space-X will continue to do new and exciting things to make space travel cheaper and safer.

 

Shadoof

Gecko.jpg

In this picture above it can be seen that the gecko is standing on the water, but how?

Well, in between the water molecules in this tank there are hydrogen bonds that connect the molecules together. What is surprising is that the gecko is able to stand and walk on the waters surface and not just stand on the surface. You can see that the water is 'bending' under the weight of the gecko and that the bonds in between the molecules have enough force to not break and let the gecko fall through.

The way the gecko is able to stand on the water is to maximize its surface area as to not put all of its downward force onto one spot on the water. This works on the same principle that a snow shoe works. The larger the surface area, the more weight can be held by the water. This also works if a leaf is thrown onto some water, the leaf does not float but rather does not even break the surface of the water.

Shadoof

As you know I have written many a blog posts about sailing. Now when it turns cold in the winter, normal sailing has to stop because of the ice. But some persistent people can't let sailing go over the winter. They take to the ice.

What is so surprising about ice sailing is that the 'boats' go much faster than they do in water. And I mean a lot faster.

The main explanation as to why the boats go faster is because of the drastic reduction in friction that occurs. The boats that are made to sail on the ice only come in contact with the ice on relatively small ice skates. Now compared to the friction that happens with a normal boat pushing through the water, these boats can reach some pretty significant speeds.

 

When it's not as cold and there is no access to water, people take to the desert for land sailing. People have reached speeds 126 mph, and the name of the game is efficiency and reducing friction.

 

Shadoof

The Serenity of Snow

If you live anywhere remotely cold, you have experienced one thing snow. With snow comes many things, terrible driving, ice, shoveling driveways, all not fun things. But if you have ever taken a walk through the woods on a snowy day, you will recognize one thing, or rather a lack of one thing, sound.

The reason why it becomes so quiet when there is snow on the ground is due to the physical shape of a snow flake. Because there are so many snowflakes on the ground, there is a lot of empty space between them. This large amount of space causes the snow on the ground to be a very good sound insulator.

To test this out next time there is snow on the ground, grab a friend, go outside and stick your head under the snow and yell. Your friend can then observe how muffled your sound becomes.

Shadoof

Maglev Trains

In my previous blog post I talked about how the Hyper Loop worked, the maglev train works in a very similar manner just in a less efficient way.

train.gif

As seen above the train actually wraps around the track and 'floats' on the track by using magnets to pull the train up into the air to reduce any friction of the track. There is also a 'guidance' magnet to make sure that the train stays centered on the track and that it won't crash into the sides.

As mentioned in my Hyper Loop blog air resistance can be a huge factor as to how fast these trains can go. Because these trains are not in a sealed tube they have to deal with the problem of air resistance, this is solved by giving the train a very pointy front as to cut through the air more efficiently.

trainfront.jpg

(Personally I think they look a little like a platypus)

 

Shadoof

Hyperloop

Some of you may know about the new development from the amazing person that is Elon Musk, the hyper loop, The new radical form of transportation could make trips from NYC to LA take under 4 hours. The ways this is possible is how the system will be operated in tubes that air will be sucked out of drastically reducing the air pressure and therefore reducing the air resistance the pod has to counteract. Another technology that the system will use is magnetic levitation, which is currently used in high-speed trains. When the pod floats in the air it will reduce the drag on the ground because it will not be touching anything. This dirastic reduction of friction from the air and from the ground allows this pod to go close to 800 mph will very little energy lost to friction.

hyperloop.jpg

Predictions on when this new form of transportation will be ready is around 2018, here's hoping.

Shadoof

The Deathroll

In small boat sailing there is a type of capsize called the deathroll, and from the name you can probably tell that it is not the most fun thing to do.

Let me start off with a picture of this looks and it will help with the of how this happens.

deathroll.jpg

Here we can see that is quite windy and that the boat is also on its side, not good. This can happen when one sails in a direction called "by the lee", this is when the flow of wind on the sail becomes reversed from the normal direction.

bythelee.jpg

On the right, called downwind, the wind is following across the sail from left to right, or from the mast (the big dot) to the end of the sail (the leech). This is how normal sail flow works, but when we go to "by the lee" the direction of the wind across the sail changes from leech to luff (end of the sail to the mast) as shown by the green arrow. When this type of flow exists on the sail the direction of the force of the sail also changes direction. On the left of the diagram the boat will tend towards leaning to the right, this is the same direction the force of the sail is in. On the right of the diagram the force of the sail is towards the left causing the boat to want to capsize like the first picture.

 

This can be explained by this diagram.

forces.gif

Now imagine the direction of the arrows reversed.

Untitled.png (My terrible paint rendition)
 

The big arrow represents the force of the sail and we can see that it is pointed to the side of the boat that the sail is not on, this leads to our dreaded deathroll.

Shadoof

The Physics of Hiking

In dinghy sailing a persons weight becomes a much bigger deal in sailing the boat and keeping it upright. As it gets windier out on the water more force is applied to the sail, and the boat is tipped, or heeled, over more. This is were the weight of the sailor becomes more important. In order to counteract the tipping force of the sail, the sailor needs to move their weight out of the boat to create a stable system.

 hiking.jpg

In the picture above we can see that the sailor has to "hike" out of the boat to counteract the force of the sail pushing the boat towards a capsize. Since the wind is always changing the sailor needs to constantly be moving around and shifting their weight in and out of the boat. This is very similar to how torque work in that the farther a mass is out of the center the more force it applies in the direction of gravity.

If the system of the boat is not in equilibrium, caused by lack of hiking or a strong gust of wind, the boat can end up on it's side, this is called a capsize.

lasercapsize.jpg

Shadoof

Physics of a Sail

Most people think that a sail works only in one direction, thanks in part to the tall ships of the past.

tallship.jpg (these things)

What appears to be happening here is the wind is just pushing the sails and then in turn pushing the boat forward. But what actually is happening here is a vacuum.

As the wind fills in the sail it creates a high pressure system on the inside, the lack of wind on the front side of the sail creates a low pressure zone, and since systems move towards a lower pressure the boat gets pulled forward.

This also applies to modern boats and this lets boats go into the wind

.forces.gif

You can see that the resultant force pulls the boat forwards, and so the boat would naturally get pulled sideways. This is solved with a board that is put directly beneath the boat so the sideways force it directed forward.

laser.png

Shadoof

In my previous blog I talked about the world of high performance sailing, this involves racing around a course. But then there is the boats specifically designed to go as fast as possible in a straight line, the boat that currently holds this record does not look like your average boat, its only purpose is a single direction as fast as possible.

Here is a diagram going into how it works.

Sailrocket_diag.png

(Some is cut off, only image I could find that explained it and wasn't in french.)

At the begging of the run this boat is very slow and just gets pushed sideways by the wind as it has no keel to keep it moving forward, but once moving it takes off reaching a record speed of 78.93 mph.

(Video contains swearing sorry)

And with speed and max efficiency there is always some error bound to happen.

 

Shadoof

The world of sailing includes many different sub types including cursing, local racing, national racing, and high performance racing. Today I am going to talking about the very interesting world of high performance racing. The most known race in sailing is most likely the Americas Cup, for this race they used boats called AC 72's (pictured below).

 181587526.jpg

Whats so surprising about these boats is the fact that they fly above the water using fins called hydrofoils.

Hydrofoil.png

What makes this so surprising is the fin's ability to lift the entire weight of the boat, 6.5 tons, on the size of a surfboard. By having the ability to sail above the water the boats are able to reach much greater speeds than previously achievable. Most mono-hull boats are only able to go a few knots, but once boats are put on foils, the hull of the boat is able to come out of the water to vastly reduce drag through the water. This allows some hydro foiling boats the ability to reach speeds greater than 60 mph.

Another factor that helps the boats reach these speeds is their sail design, the AC 72's have very unique sails in their size and design. What is so unique about their design is that they are solid wings as opposed to the normal canvas that many sailboats carry. The size of their sail is also very large compared to the length and the width of the boat. The boat is only 72.2 ft long while the main sail is 131 ft tall, the way this is possible is because the boat is so wide that it is more difficult for the boat to capsize.

AC_72_Team_Oracle_photo_D_Ramey_Logan.jpg

This foiling can also apply to some mono-hulls including the moth,

moth.jpg

and some newer experimental boats,

IMOCA 60.jpg

 

With speed the risk of failure increases greatly as well...

OR

 

 

Shadoof

Lifting a Boat

As said in my about me post, I like sailing, and let me tell you something there is a lot of physics in the sport of sailing. To start with the basic, I am going to talk first about getting the boat in the water. Often people keep their boats on trailers and lift them into the water every time they are going for a sail. This is no simple task as the particular boat I sail weighs in the neighborhood of 3,100 lbs (1.55 US Tons).

IMG_20161002_165209.jpg

To help with this problem there are cranes provided that we can use to lift the boat into the water that have a max weight of 2 tons.

IMG_20161002_165228.jpg

The crane's arm is about 6m long, so with the torque equation  \tau  = rF we can find the torque put on the crane. \tau =(6m)(13789N) = 82734mN, for context if you hold a liter of water (1kg) at arms length (.5m) thats only about 4.9mN of torque on your arm. The crane does have a max weight that can be put on it, so the max torque that can be applied to the crane would be 106752mN. There are countless other things that could affect the lifting strength of the crane including the chain that leads to the hook. The max strength that this chain should hold would be about 17792N. If the equipment is not in good condition then failure can happen and you are left with a boat that is smashed on the concrete and possible personal injury (speaking with experience).

Thanks to modern technology and materials this feat of physics can be accomplished for a nice sail.

boat.jpg

Shadoof

Huston we have a problem

On Friday September 16th our class was assigned the task to shoot a book with a ball. Some may say a very simple task, yet we failed anyway. Some problems that could have caused this failure was the lack of communication between everybody working alone, and also the lack of similar measurements. To redeem ourselves we were given the opportunity to redo the lab as a blog to get full credit, instead of a big fat 0.

The ball was shot in the x direction at a rate of 4.64 m/s and in the y direction at a rate of .32 m/s. After calculating the initial velocity we could determine the time it would be in the air using the formula ∆y= vt + ½at². Plugging in the known values, (1.035 = .32t + ½(9.8)t²) for this I could use the quadratic equation to solve for t, getting a positive value of .43 seconds. Then using the time and the velocity in the x direction it is easy to determine how far it will go. Using ∆x = vt, we can plug in our time and velocity to get 1.99m. 

Shadoof

All about me

Hello, I am a person that likes to sail, and do outdoor things like camping. My strengths include math and science. I hope to become an computer or electrical engineer. I am taking physics to help gain more college credits and to also learn if this is something I want to do. I would like to learn about how things interact with each other in this universe. I am excited to do labs and have fun. I am anxious about completing all of the work assigned in time and keeping my grade up.

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