how rocket works

A rocket in its simplest form is a chamber enclosing a gas under pressure. A small opening at one end of the chamber allows the gas to escape, and in doing so provides a thrust that propels the rocket in the opposite direction. A good example of this is a balloon. Air inside a balloon is compressed by the balloon's rubber walls. The air pushes back so that the inward and outward pressing forces balance. When the nozzle is released, air escapes through it and the balloon is propelled in the opposite direction.When we think of rockets, we rarely think of balloons. Instead, our attention is drawn to the giant vehicles that carry satellites into orbit and spacecraft to the Moon and planets. Nevertheless, there is a strong similarity between the two. The only significant difference is the way the pressurized gas is produced. With space rockets, the gas is produced by burning propellants that can be solid or liquid in form or a combination of the two. One of the interesting facts about the historical development of rockets is that while rockets and rocket-powered devices have been in use for more than two thousand years, it has been only in the last three hundred years that rocket experimenters have had a scientific basis for understanding how they work. The science of rocketry began with the publishing of a book in 1687 by the great English scientist Sir Isaac Newton. His book, entitled Philosophiae Naturalis Principia Mathematica, described physical principles in nature. Today, Newton's work is usually just called the Principia. In the Principia, Newton stated three important scientific principles that govern the motion of all objects, whether on Earth or in space. Knowing these principles, now called Newton's Laws of Motion, rocketeers have been able to construct the modern giant rockets of the 20th century such as the Saturn 5 and the Space Shuttle. Here now, in simple form, are Newton's Laws of Motion. Objects at rest will stay at rest and objects in motion will stay in motion in a straight line unless acted upon by an unbalanced force. Force is equal to mass times acceleration. For every action there is always an opposite and equal reaction. As will be explained shortly, all three laws are really simple statements of how things move. But with them, precise determinations of rocket performance can be made. Newton's First Law This law of motion is just an obvious statement of fact, but to know what it means, it is necessary to understand the terms rest, motion, and unbalanced force.Rest and motion can be thought of as being opposite to each other. Rest is the state of an object when it is not changing position in relation to its surroundings. If you are sitting still in a chair, you can be said to be at rest. This term, however, is relative. Your chair may actually be one of many seats on a speeding airplane. The important thing to remember here is that you are not moving in relation to your immediate surroundings. If rest were defined as a total absence of motion, it would not exist in nature. Even if you were sitting in your chair at home, you would still be moving, because your chair is actually sitting on the surface of a spinning planet that is orbiting a star. The star is moving through a rotating galaxy that is, itself, moving through the universe. While sitting "still," you are, in fact, traveling at a speed of hundreds of kilometers per second. Motion is also a relative term. All matter in the universe is moving all the time, but in the first law, motion here means changing position in relation to surroundings. A ball is at rest if it is sitting on the ground. The ball is in motion if it is rolling. A rolling ball changes its position in relation to its surroundings. When you are sitting on a chair in an airplane, you are at rest, but if you get up and walk down the aisle, you are in motion. A rocket blasting off the launch pad changes from a state of rest to a state of motion. The third term important to understanding this law is unbalanced force. If you hold a ball in your hand and keep it still, the ball is at rest. All the time the ball is held there though, it is being acted upon by forces. The force of gravity is trying to pull the ball downward, while at the same time your hand is pushing against the ball to hold it up. The forces acting on the ball are balanced. Let the ball go, or move your hand upward, and the forces become unbalanced. The ball then changes from a state of rest to a state of motion. In rocket flight, forces become balanced and unbalanced all the time. A rocket on the launch pad is balanced. The surface of the pad pushes the rocket up while gravity tries to pull it down. As the engines are ignited, the thrust from the rocket unbalances the forces, and the rocket travels upward. Later, when the rocket runs out of fuel, it slows down, stops at the highest point of its flight, and then falls back to Earth. Objects in space also react to forces. A spacecraft moving through the solar system is in constant motion. The spacecraft will travel in a straight line if the forces on it are in balance. This happens only when the spacecraft is very far from any large gravity source such as Earth or the other planets and their moons. If the spacecraft The combination of a satellite's forward motion and the pull of gravity of the planet, bend the satellite's path into an orbit. comes near a large body in space, the gravity of that body will unbalance the forces and curve the path of the spacecraft. This happens, in particular, when a satellite is sent by a rocket on a path that is tangent to the planned orbit about a planet. The unbalanced gravitational force causes the satellite's path to change to an arc. The arc is a combination of the satellite's fall inward toward the planet's center and its forward motion. When these two motions are just right, the shape of the satellite's path matches the shape of the body it is traveling around. Consequently, an orbit is produced. Since the gravitational force changes with height above a planet, each altitude has its own unique velocity that results in a circular orbit. Obviously, controlling velocity is extremely important for maintaining the circular orbit of the spacecraft. Unless another unbalanced force, such as friction with gas molecules in orbit or the firing of a rocket engine in the opposite direction, slows down the spacecraft, it will orbit the planet forever. Now that the three major terms of this first law have been explained, it is possible to restate this law. If an object, such as a rocket, is at rest, it takes an unbalanced force to make it move. If the object is already moving, it takes an unbalanced force, to stop it, change its direction from a straight line path, or alter its speed. Newton's Third Law For the time being, we will skip the Second Law and go directly to the Third. This law states that every action has an equal and opposite reaction. If you have ever stepped off a small boat that has not been properly tied to a pier, you will know exactly what this law means.A rocket can liftoff from a launch pad only when it expels gas out of its engine. The rocket pushes on the gas, and the gas in turn pushes on the rocket. The whole process is very similar to riding a skateboard. Imagine that a skateboard and rider are in a state of rest (not moving). The rider jumps off the skateboard. In the Third Law, the jumping is called an action. The skateboard responds to that action by traveling some distance in the opposite direction. The skateboard's opposite motion is called a reaction. When the distance traveled by the rider and the skateboard are compared, it would appear that the skateboard has had a much greater reaction than the action of the rider. This is not the case. The reason the skateboard has traveled farther is that it has less mass than the rider. This concept will be better explained in a discussion of the Second Law. With rockets, the action is the expelling of gas out of the engine. The reaction is the movement of the rocket in the opposite direction. To enable a rocket to lift off from the launch pad, the action, or thrust, from the engine must be greater than the weight of the rocket. While on the pad the weight of the rocket is balanced by the force of the ground pushing against it. Small amounts of thrust result in less force required by the ground to keep the rocket balanced. Only when the thrust is greater than the weight of the rocket does the force become unbalanced and the rocket lifts off. In space where unbalanced force is used to maintain the orbit, even tiny thrusts will cause a change in the unbalanced force and result in the rocket changing speed or direction. One of the most commonly asked questions about rockets is how they can work in space where there is no air for them to push against. The answer to this question comes from the Third Law. Imagine the skateboard again. On the ground, the only part air plays in the motions of the rider and the skateboard is to slow them down. Moving through the air causes friction, or as scientists call it, drag. The surrounding air impedes the action-reaction. As a result rockets actually work better in space than they do in air. As the exhaust gas leaves the rocket engine it must push away the surrounding air; this uses up some of the energy of the rocket. In space, the exhaust gases can escape freely. Newton's Second Law This law of motion is essentially a statement of a mathematical equation. The three parts of the equation are mass (m), acceleration (a), and force (f). Using letters to symbolize each part, the equation can be written as follows: f = maThe equation reads: force equals mass times acceleration. To explain this law, we will use an old style cannon as an example. When the cannon is fired, an explosion propels a cannon ball out the open end of the barrel. It flies a kilometer or two to its target. At the same time the cannon itself is pushed backward a meter or two. This is action and reaction at work (Third Law). The force acting on the cannon and the ball is the same. What happens to the cannon and the ball is determined by the Second Law. Look at the two equations below. f = m(cannon) a(cannon)f = m(ball) a(ball) The first equation refers to the cannon and the second to the cannon ball. In the first equation, the mass is the cannon itself and the acceleration is the movement of the cannon. In the second equation the mass is the cannon ball and the acceleration is its movement. Because the force (exploding gun powder) is the same for the two equations, the equations can be combined and rewritten below. m(cannon) a(cannon) = m(ball) a(ball)In order to keep the two sides of the equations equal, the accelerations vary with mass. In other words, the cannon has a large mass and a small acceleration. The cannon ball has a small mass and a large acceleration. Apply this principle to a rocket. Replace the mass of the cannon ball with the mass of the gases being ejected out of the rocket engine. Replace the mass of the cannon with the mass of the rocket moving in the other direction. Force is the pressure created by the controlled explosion taking place inside the rocket's engines. That pressure accelerates the gas one way and the rocket the other. Some interesting things happen with rockets that do not happen with the cannon and ball in this example. With the cannon and cannon ball, the thrust lasts for just a moment. The thrust for the rocket continues as long as its engines are firing. Furthermore, the mass of the rocket changes during flight. Its mass is the sum of all its parts. Rocket parts include: engines, propellant tanks, payload, control system, and propellants. By far, the largest part of the rocket's mass is its propellants. But that amount constantly changes as the engines fire. That means that the rocket's mass gets smaller during flight. In order for the left side of our equation to remain in balance with the right side, acceleration of the rocket has to increase as its mass decreases. That is why a rocket starts off moving slowly and goes faster and faster as it climbs into space. Newton's Second Law of Motion is especially useful when designing efficient rockets. To enable a rocket to climb into low Earth orbit, it is necessary to achieve a speed, in excess of 28,000 km per hour. A speed of over 40,250 km per hour, called escape velocity, enables a rocket to leave Earth and travel out into deep space. Attaining space flight speeds requires the rocket engine to achieve the greatest action force possible in the shortest time. In other words, the engine must burn a large mass of fuel and push the resulting gas out of the engine as rapidly as possible. Ways of doing this will be described in the next chapter. Newton's Second Law of Motion can be restated in the following way: the greater the mass of rocket fuel burned, and the faster the gas produced can escape the engine, the greater the thrust of the rocket. Putting Newton's Laws of Motion Together An unbalanced force must be exerted for a rocket to lift off from a launch pad or for a craft in space to change speed or direction (First Law). The amount of thrust (force) produced by a rocket engine will be determined by the rate at which the mass of the rocket fuel burns and the speed of the gas escaping the rocket (Second Law). The reaction, or motion, of the rocket is equal to and in the opposite direction of the action, or thrust, from the engine (Third Law).

"How to Impress a Girl"

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1. Be well-groomed. Brush your hair, shower, wash your face use deodorant, a little cologne, and apply acne medicine daily (if you have a problem with your skin). Don't wear your pants off your butt, often called "sagging", it's not that attractive to the majority of girls. This is essential if you are even going to approach an attractive girl . Wear clean, attractive clothes that fit. (If in doubt, get an older sister or close female friend to help you in this department.) Don't wear skin tight clothes, but don't wear clothes that are too baggy either, girls hate that.
   
   
   
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   Have a great attitude. Be fun to hang around with, easy to laugh with, and be outgoing. Just don't be full of yourself. A girl may like an overly cocky guy at first, but eventually, she will find it selfish. Don't try to impress everyone - girls like humble guys. At the same time, a sense of humor is always good. Girls love it when guys can make them laugh.
   
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   Show respect. If you respect everyone and give them their space, they'll all respect you. With girls, it works even better. If they see you respecting everyone, and not getting pushed around while you're at it, they will be reassured that you will treat them right. Be kind to all.
   
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   Have good conversations. Try to aim for you both to be speaking half of the time, but make sure that you are saying something worthwhile; it's not attractive when only one person talks endlessly or when they say bad words. Another thing to watch for is her attention. If she isn't paying complete attention, do not repeat yourself several times. This makes girls feel you are desperate, and usually annoying.
   
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   Show interest in her - let her talk. The #1 mistake when talking to a girl is focusing on yourself. Girls are way more comfortable when they talk about common interests. Ask about their interests, hobbies, favorite books, music, etc. If she asks you a question, answer it in a few, short sentences and then redirect the question back at her. This engages her in the conversation. When in doubt, compliment her like your hair looks nice today. Even if a girl does not like you yet, complimenting her will make her feel good about herself and think positively about you.
   
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   Try flirting! Don't be obsessive! If you both make eye contact, do not be the one to look away, but do not stare for too long. When you both make eye contact, just give a slight smile. Touch her arm or shoulder for a few seconds. Physical contact is a great way to show you're interested. If she seems uncomfortable, do not do it again.
   
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   She may look away and she might blush a little. Be careful though; you don't want to stare her down. A good move is to look away, and if she likes you she will shoot you glances. Watch for that. And be courteous. Open doors. Do kind things, girls love that.
   
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   Respect her friends and their ideas and opinions. Always speak highly of her and never talk trash about her. It will damage her reputation and yours. Hopefully then it will work both ways - she will be tolerant of your friends. Be careful not to compliment her friends too much, however. Example: You may say "Your friends seem cool. We should hang out with them and my friends some time, I think they'd get along". You may not say "Sally is so hot. She has the nicest eyes". You may think getting her jealous is a good idea, but it just makes them angry.
   
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   Have your friends be nice to her It's a fantastic thing when your friends don't make a total fool of you. Warn them ahead of time and avoid topics pertaining to embarrassing moments of your past or awkward jokes that make very little sense. Don't introduce her to your friends right away though. You want her to like you, not start dating one of your buddies. If your friends like to embarrass you, try to avoid them altogether.
   
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    Be polite to her parents. Be kind to everyone, especially them. Don't be too over-the-top charming with the parents, however, or they'll think that you have something to hide.Be willing make sure that you and her father get along as he will be looking out for his daughter.
    
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    Don't criticize her. Unless she asks for constructive criticism. And even then she probably wants you to compliment her.
    
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    Be romantic, but not over the top. If you've been dating for a while you may attempt a grand romantic gesture, otherwise, you'll look like a stalker. It's also okay to be a little cheesy, like giving her a bouquet of roses and a loving poem. It may sound like a bad idea, but girls will find it thoughtful if it came from your heart. A better idea than being cheesy is to really LISTEN to her & remember things she likes. Then take her somewhere she's mentioned wanting to go, or buy her the books she's been wanting & hide a little note inside. Flowers & candy are really cliche & don't really mean much since anyone can just buy someone flowers. Showing you've been listening to her wants & needs goes a LOT farther than roses!!
    
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    Start talking to her casually. If you don't know her, make friendly conversation. Ask for the time, and/or compliment her watch. Avoid throwing too many compliments about clothes or shoes around, that might make women think that you are homosexual as many gay men are fashion-forward.
    
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    Do not play "hard to get". Sure, you'll get their attention for a day or two then after a while, the girl will end up frustrated, and she'll think you don't find interest in her anymore.
    
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    Be careful with what you say. Do not discuss bodily functions in her presence, or make jokes of a sexual nature unless she starts doing so. Also, don't discuss anything gross or inappropriate. She'll get grossed out.
    
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    Hum in her presence She might think of you whenever she hears that song. And she'll probably be impressed by your good taste in music. Some girls have actually dumped guys or stopped liking guys when they insulted the music they like. So, it's OK not to like her music, but don't be insulting her favorite singer(s)/band(s)! Try to figure out what music you BOTH like.
    
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    Start an inside joke with her! She will feel included and become closer to you. It also gives you an easy-to-come-up-with conversation starter. Try not to overuse it and kill the joke.
    
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    End later meetings with a hug, or plans to meet some other time, if you can. Make sure to tell her that you enjoyed her company.
    
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    Tell her that you "like her" frequently. Ask her out.
    
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    Touch her occasionally, like on the shoulder or hand. Be sure do not touch her private parts, however.
    
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    Opposites attract. Be a courageous gentleman, not coy like a lady might be. Stand up for her if something is wrong.
    
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    Show your funny side. A lot of women look for sense of humor in a partner. You should however be mindful of their reactions to your jokes and avoid offensive humor. Unless they like that. Find out if she likes comedy. If she watches Comedy Central, find out her favorite comedian or favorite impression and try it out for her.
    
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    Make her feel good. This is a really good thing that impresses girls. They love it when you let them know you care for them. If she's sad, just simply put your arm around her neck. Make her happy, at least as much as you can. Flirt with her, hold her hand it will make her feel special.
    
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    Don't ever make fun of your friends around her If you do, it might make her think that you're a jerk. When someone makes fun of other people, it makes a woman wonder what they might be saying about HER when she's not around!!!
    
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    Be honest. Do something creative, something extraordinary or something that others never do. That creates a question mark for the girl about you, and it also makes you interesting.
    
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    Be open. Don't share too many secrets with her. Sprinkle a little and don't irritate her asking repeated questions. Always keep your face glowing and charming.
    

Embedded Systems IN ADIDAS

 

Adidas has developed the world's first "smart shoe" that uses a microprocessor to adapt the shoe's cushioning level to a runner's size, stride and comfort. Adidas 1 , the smart shoe is the result of a closely-held, four-year project at the European company's U.S. research and development headquarters in Portland, Ore. Adidas claims its smart show will revolutionize long-distance running and training. This great innovation adds to the company’s prestigious list of seven hundred patents and other intellectual property rights.

CONCEPT

 “It senses, understands and adapts”. The shoe provides intelligent cushioning by automatically and continuously adjusting itself. It does so by sensing the cushioning level, using a sensor and a magnet. It then understands whether the cushioning level is too soft or too firm using a micro processor. It adapts with a motor-driven cable system to provide the correct cushioning throughout the run. 

TECHNOLOGY

It works like a human reflex nerve. The nerve is a magnetic sensing system, where the sensor sits just below the runner's heel and the magnet is placed at the bottom of the midsole. On each impact, this sensor measures the distance from top to bottom of the midsole (accurate to .1 mm) gauging the compression and therefore the amount of cushioning is being used.

Underneath the arch is a microprocessor (20 MHz). The entire microprocessor kit weighs less than 40 grams, or about 10 percent of an average weight of running shoe. The design seeks for reduce weight and drag for long-distance runners. The algorithms, that are designed specifically for the shoe compares the compression messages received from the sensor to a preset zone and understands if the shoe is too soft or too firm. 

Once it has determined if the cushioning level is appropriate, it sends a command to the shoe's muscle to make a change. 

A motor-driven cable system is the shoe's muscle. The motor, housed in the mid foot, receives the processor's instructions and adapts by turning a screw, which lengthens or shortens a cable. This cable is secured to the walls of a plastic cushioning element. When the cable is shortened, the cushioning element is tensed and only a little compression is allowed (becomes firm). When the cable is longer, it allows the cushioning element to compress further, making the shoe's ride softer. A small battery, which is replaceable and lasts for 100 hours of running, provides the motor's power. The changes are gradual and happen automatically, so all the runner notices is that, the shoe feels right during an entire run. For manual adjustments, two buttons have been provide that will let the user, adjust compression resistance up or down.

 After thousands of hours of prototyping and testing, it has been declared that, it can endure the wear-and-tear of running on surfaces ranging from pavement, dirt trails or even beaches. This technological innovation is surely a positive step toward ‘the next-generation of running shoes’. I am sure, no one could help your selves from finding out on first-hand, whether having a little computational power would make any difference in our daily workout

15 tips for placement

The thought of writing a resume intimidates almost anyone. It's difficult to know where to start or what to include. It can seem like an insurmountable task. Here are 15 tips to help you not only tackle the task, but also write a winning resume.
Determine your job search objective prior to writing the resume
Once you have determined your objective, you can structure the content of your resume around that objective. Think of your objective as the bull's-eye to focus your resume on hitting. If you write your resume without having a clear objective in mind, it will likely come across as unfocused to those that read it. Take the time before you start your resume to form a clear objective.
Think of your resume as a marketing tool
Think of yourself as a product, potential employers as your customers, and your resume as a brochure about you. Market yourself through your resume. What are your features and benefits? What makes you unique? Make sure to convey this information in your resume.
Use your resume to obtain an interview, not a job
You don't need to go into detail about every accomplishment. Strive to be clear and concise. The purpose of your resume is to generate enough interest in you to have an employer contact you for an interview. Use the interview to provide a more detailed explanation of your accomplishments and to land a job offer.
Use bulleted sentences
In the body of your resume, use bullets with short sentences rather than lengthy paragraphs. Resumes are read quickly. This bulleted sentence format makes it easier for someone to quickly scan your resume and still absorb it.
Use action words
Action words cause your resume to pop. To add life to your resume, use bulleted sentences that begin with action words like prepared, developed, monitored, and presented.
Use #'s, $'s and %'s
Numbers, dollars, and percentages stand out in the body of a resume. Use them. Here are two examples:
Managed a department of 10 with a budget of $1,000,000.
Increased sales by 25% in a 15-state territory.
Lead with your strengths
Since resumes are typically reviewed in 30 seconds, take the time to determine which bullets most strongly support your job search objective. Put those strong points first where they are more apt to be read.
Play Match Game
Review want ads for positions that interest you. Use the key words listed in these ads to match them to bullets in your resume. If you have missed any key words, add them to your resume.
Use buzzwords
If there are terms that show your competence in a particular field, use them in your resume. For marketing people, use "competitive analysis." For accounting types, use "reconciled accounts."
Accent the positive
Leave off negatives and irrelevant points. If you feel your date of graduation will subject you to age discrimination, leave the date off your resume. If you do some duties in your current job that don't support your job search objective, leave them off your resume. Focus on the duties that do support your objective. Leave off irrelevant personal information like your height and weight.
Show what you know
Rather than going into depth in one area, use your resume to highlight your breadth of knowledge. Use an interview to provide more detail.
Show who you know
If you have reported to someone important such as a vice president or department manager, say so in your resume. Having reported to someone important causes the reader to infer that you are important.
Construct your resume to read easily
Leave white space. Use a font size no smaller than 10 point. Limit the length of your resume to 1-2 pages. Remember, resumes are reviewed quickly. Help the reader to scan your resume efficiently and effectively.
Have someone else review your resume
Since you are so close to your situation, it can be difficult for you to hit all your high points and clearly convey all your accomplishments. Have someone review your job search objective, your resume, and listings of positions that interest you. Encourage them to ask questions. Their questions can help you to discover items you inadvertently left off your resume. Revise your resume to include these items. Their questions can also point to items on your resume that are confusing to the reader. Clarify your resume based on this input.
Submit your resume to potential employers
Have the courage to submit your resume. Think of it as a game where your odds of winning increase with every resume you submit. You really do increase your odds with every resume you submit. Use a three-tiered approach. Apply for some jobs that appear to be beneath you. Perhaps they will turn out to be more than they appeared to be once you interview for them. Or perhaps once you have your foot in the door you can learn of other opportunities. Apply for jobs that seem to be just at your level. You will get interviews for some of those jobs. See how each job stacks up. Try for some jobs that seem like a stretch. That's how you grow -- by taking risks. Don't rule yourself out. Trust the process. Good luck in your job search!