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I'm taking physics this year is because I want to know how things happen. Taking Physics C will help me understand the world around me, and teach me valuable studying techniques. It is a college level course and all. Over the next 9 months, I will be discussing real world applications of physics (to the best of my ability). Stop by every week for your healthy dose of knowledge and entertainment. Or don't, I'll still get an A.

## Double Dominos

Double domino's are relatively hard to explain so you should watch the video to get a good idea of what it is.  This is possible because the bricks are very wide. when the bricks fall, they lay on top of the one before it. the last brick in the sequence does not have anything to lay on so it falls to the floor. this causes the brick that is laying on it to fall as well and the next brick to fall and so on. This happens only when the bricks are placed a certain distance away from each other. this distance cant be too close or the bricks will just rest on top of each other. this distance also cant be too far away or the bricks will lay flat on the floor after hitting.

## Fiber-Optic Cables

fiber optic cables are used to send messages at high speeds and at great distances. There exists a fiber optic cable traveling from New Jersey to England! fiber optic cables work by sending pulsing light through a specific material. since light is the fastest thing in the universe, fiber optic cables are the fastest form of communication in the known universe. as you know, light travels at different speeds when its inside of a different median. the ratio of the speed of light in air to the speed inside of the material is known as the index of refraction. a higher index of refraction means that light moves slower through the material. the core of a fiber optic cable has a much higher index of refraction than the outer layer. when light travels through the core, it is reflected off the boundary between the materials. this allows the cables to bend and not lose light.

## Can Openers

The tab on top of a soda can is more complicated than it may seem. First, the tab acts as a second class lever. a second class lever is a lever in which the fulcrum is at one end and the load is in the middle. the load is the point where the tab is attached to the can. In a second class lever, the force only moves up. One example of a second class lever is a wheelbarrow. The rivet in the middle of the can is pulled up until it reaches a point where a small crevice opens up. once this crevice appears, the tab immediately turns into a first class lever. a first class lever is when the fulcrum is in the middle, and the load is on one end while the force is on the other end. an example of a first class lever is a see saw. the first class lever is used to push the top down into the can, allowing you to drink from it. The crevice in the can is very important in the opening process. The can has so much pressure that just pushing down on the seal would require a tremendous amount of force. cans would need a very long tab, which would be impractical. the crevice releases pressure in the can.  skip to 9:13 for the stuff about the can opener.

## Microwaves

I noticed a peculiar message on my package of noodles when making dinner the other night. It said something like "microwave on high (1.0kW) for 2 minutes". I was rather confused. I thought that all microwaves had the same cooking ability, but apparently not. The "1.0kW" section of the instructions indicated to the power of my microwave. The noodles required that I use 1000 watts of power for 2 minutes in order to cook properly. Electrical energy is calculated using E=P*t, and is measured in kilowatthours(kWh). The noodles only require an energy of .033kWh. My microwave has 1500 watts. That means that I would only have to cook my noodles for 1:20 minutes in order to meet the proper energy consumption. So I, being the impatient problem solver that I am, set my microwave to the proper time and hit go! My noodles were cold >:(

## Trampolines

Recently I went to Altitude, a trampoline park. Trampolines make you jump really high. Trampolines are made of a woven material that is connected to springs on all sides. These springs are what give trampolines their ability to throw people in the air. Lets say that the trampolines at altitude can make me jump 2 meters high. That would mean I have a gravitational potential energy of 1245 joules at a height of 2 meters. All of that energy would be converted to elastic potential energy when I jump on the trampoline. 1245 joules of elastic potential energy means that the trampolines have a spring constant of 622.5 N/m.

## Coin Flips

Does a coin have an equal chance to land on both sides? no actually. there is a 51% chance that your coin will land tails up compared to heads up. that is why tails never fails (only 49% of the time). This is because the head of the president on a coin is made of more material than the building or symbol on the tail side. There is a better chance that if you spin a coin on a table, it will land tails up. Certain coins can have an 80% chance that they will land tails side up. Keep this in mind next time you want to win a bet.

## Guillotines

A guillotine is a medieval weapon used for public execution of prisoners. the way that a guillotine works is a blade attached to two parallel tracks drops onto a persons neck, displacing their head from their body. the blade of a guillotine has potential energy when it is at the top of the tracks. that potential energy is converted into kinetic energy when the blade is dropped. the blade is able to separate a human head from a body because it has a lot of energy. normally, guillotine blades are very heavy. this enables them to have a lot more gravitational potential energy because Ug=mgh. a more massive blade also means more force on the neck. this is because F=ma.

## Superelastic Collisions

We all know about inelastic and elastic collisions. inelastic collisions are when two or more objects stick together after contact. elastic collisions are when two or more objects bounce off each other after contact. what on earth is a superelastic collision then? first, an inelastic collision is when the kinetic energy before the collision is greater than the kinetic energy after. an elastic collision is when the kinetic energy before a collision equals the kinetic energy after the collision. therefore, a superelastic collision is when the kinetic energy before a collision is less than the kinetic energy after the collision. what does this look like you may ask? imagine a land mine for instance. when your foot collides with the pressure plate on a land mine, some kinetic energy was exhibited. the instant your foot hits the pressure plate, the land mine explodes and your guts and limbs are scattered. the kinetic energy of your foot before making contact with the pressure plate is less than the kinetic energy of your foot being hurled into a tree hundreds of feet away.

The Dead Sea is a lake that is bordering Jordan on the left and Israel on the right. The dead sea is special because it is the most extreme hyper-saline lakes in the world. a hyper-saline lake is a body of water that has high levels of sodium chloride. Hyper-saline lakes are saltier than the salt water that makes up our oceans. The dead sea is the most extreme meaning that it has the highest salt content of 33.7%. The salt water in the ocean only has a salt content of 3.5%. the dead sea got its name because of its high salt content. when people swim in it, their natural buoyancy enables them to float as if they were dead. buoyancy is when the forces under the object exceed the forces above the object. the net force of an object in a fluid is called the buoyancy force. Archimedes' principle is when the object inside of a fluid is equal to the weight of the amount of fluid displaced. this looks like when a n object is neither floating or sinking.

## Lava Lamps

Did you know that lava lamps don't actually contain any lava? lava lamps are essentially just wax and water. There are two things that make these substances unique: They have very close densities and they are insoluble between one another. the density of water is 1000kg/m^3. Insoluble means that the two substances don't mix. Water and oil are examples of insoluble substances.in lava lamps, there is a light bulb at the bottom of the glass container. the light bulb heats up the wax at the bottom. wax has a melting point of 115o F. when the wax changes from solid to liquid, the molecules begin to move apart from each other. The density changes from over 1000kg/m^3 to under 1000kg/m^3. this means that when the wax reaches a certain temperature, it begins to float. when the wax is at the top of the glass container, it begins to cool off. when the wax cools off, the molecules come back together, the wax solidifies, and the wax sinks. this constant cycle of sinking and floating wax is what creates the random flowing of liquids in a lava lamp.

## Vacuum Cleaners

So this weekend I had to clean my room. My room has a carpet floor, which means that I had to use a vacuum cleaner. Your vacuum cleaner consists of an intake, a motor, a bag, and an exhaust. A fan powered by a motor rotates causing a change in pressure. the angled fan blades push air through the bag and out the exhaust. this flow of air is creating a change in pressure. there is more pressure in the back of the fan than in the front, which creates a suction. the suction is what picks up dust on the floor and pushes it into the bag. there is a constant flow of air through the vacuum created by the rotating fan. this enables dust and debris to get caught in the stream and eventually fall into the bag where it can be discarded later.

## Cliff Diving

I've always wanted to go cliff diving, but it seems so dangerous. People have told me that if you fall high enough the water can feel like concrete. Also, if the water is too shallow, you could potentially hit the ground and get injured. The speed that you enter the water can lead to injury as well. You can reach speeds up to 25 mph when jumping from only 20 feet. jumping into water from a high point can disorient you when you land in the water. depending on how deep the water is, this can be dangerous and potentially lead to drowning. Also, if you injure yourself during the dive, it could be hard to swim to the surface. Needless to say, there is a lot of danger involved in cliff diving.  My research tells me that good form goes a long way. It is much easier to break the surface of the water if you are in a pencil shape compared to a cannon ball. The reason that a pencil dive is better than a cannon ball in terms of diving is because of work. In both the pencil and cannon ball case, the object is being acted upon by gravity, meaning that it enters the water with the same amount of force. When the object makes contact with the water, the water is moved a displacement in order to make room for the object in the new median. In a pencil dive, there is less surface area, meaning that the water displaces less. In a cannon ball, there is more surface area meaning that the water displaces more. The force of gravity does more work on the water during a cannon ball dive compared to a pencil dive. Also, mechanical energy is lost from the system when the object hits the water because the of the work done by gravity to break the surface. if both the cannon ball dive and the pencil dive have the same total energy, the cannon ball dive loses more mechanical energy because it uses more energy to do work on the water. This is why the pencil dive is able to go deeper.

## The Bloodhound

The bloodhound is a large, brown, lovable pooch that is known for it's keen sense of smell. The Bloodhound SSC is NOT a large, brown, lovable pooch that is known for its keen sense of smell. The Bloodhound SSC is the most complex racing car on the planet. This car can travel up to 1,000 miles per hour. Its less of a car however and more of a jet with 4 wheels attached to it. But nonetheless, the Bloodhound SSC is the fastest land vehicle in the world. The Bloodhound SSC has a rocket that reaches temperatures hotter than a volcano. Each of it's 4 enormous wheels spin 170 times a second. The engine in the Bloodhound SSC has 135,000 horsepower. This car is able to travel an entire mile in only 3.6 seconds. The SSC part of the Bloodhound SSC stands for Super Sonic Car. This car can travel faster than the speed of sound. The significance of traveling the speed of sound is in the interference patterns. The noise that the engine makes produces a sound wave. As you probably know, when an object is still and producing a sound, the sound waves look something like the diagram labeled "stationary". When an object is moving less than the speed of sound and producing a sound, the wave patterns look something like the diagram labeled "subsonic". The tighter areas of the sound waves produce a higher pitched sound, and the farther apart waves produce a lower pitched sound. This is boring. The fun stuff happens the instant the object reaches 340 m/s,. Hundreds of sound waves all gather at the tip of the source because the sound waves cant move fast enough to escape the source. This creates an enormous amount of constructive interference, or a really loud noise. that noise is called a sonic boom. The same sonic boom happens when an object moves faster than the speed of sound, only the constructive interference is located in a cone shape behind the object ("supersonic" diagram). The cone is referred to as the Mach cone. Anywhere outside the mach cone is the zone of silence. A sonic boom is roughly 200 decibels. For comparison, a shotgun blast is 150 decibels, a clap of thunder is 120 decibels, and that freaking vacuum cleaner that my mother is always using while I'm doing my homework is (a deafening) 88 decibels.  The ratio of an objects speed over the speed of sound is known as the Mach number. this can be written as M=v/c. Mach .5 is half the speed of sound, Mach 2 is twice the speed of sound, and so on. The Bloodhound SSC has a Mach number of 1.31. There's another physics concept known as the Mach angle. the mach angle is the angle between the direction of the velocity, and the sound wave (referred to in the diagram on the right as the Mach Line). The equation for calculating the Mach angle is sin-1(c/v) = 0. The smaller the Mach angle, the faster the object is travelling. The Mach angle of the Bloodhound SSC is only 49.5o.    The Bloodhound SSC is a remarkable piece of technology. the Bloodhound team is constantly making new discoveries and innovations every day. The Bloodhound Project is all about helping underprivileged children engage in science, technology, engineering, and math. You can support the Bloodhound Project through donations, and have your name on the fin of the car. The Bloodhound SSC team is also looking for a software engineer, for those that are interested. Thank you for taking the time to read my blog. http://www.bloodhoundssc.com/support-us#form http://www.bloodhoundssc.com/news/join-team-software-engineer-needed http://physics.info/shock/

## Pam Sapaleo

Hey All, First I'd like to thank everyone for taking time out of their busy day to read this. I was being literal when i said "busy day" because 99.9% of you reading this are taking AP Physics C, which means your busy reading to the blind or climbing mountains of homework. My name is Sam Papaleo. I play soccer, video games, some guitar, and I work at 2 Ton Tony's. I don't know what I want to be or where I want to go to college. I'm taking Physics C this year because last year I thought that I knew everything there was to know about the physics and the rest of the universe, but I was wrong (gasp). Needless to say, I have no idea what I'm doing.