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Why does the neighborhood buck? 

Reading Media

Writing is a very important communication tool. Delivery of messages between a person to another person indirectly usually done through writing. Writings that have been developed by the time include letters, numbers or symbols, some of them even have been used for thousands of years before centuries.

Media of writing was already much developed until now. In the early use of writing a lot of media used are the leaves, clay, or bark. Until finally created paper made ​​from natural fibers containing cellulose and hemicellulose. The first paper was invented by Tsai Lun and continues to grow as the main medium of writing. The paper is widely used to store the text in the form of novels, newspapers, magazines, media and other images. We read a lot of writings on paper in various forms.

With the increase of technology, now has come a variety of electronic reading media named e-book that manythings can be downloaded from the Internet. Subsequently a new hobby called e-reading, ie reading books, novels, magazines and other in e-book form. E-reading is actually a tip about reading e-books using a variety of devices such as mobile phones, tablet computer, laptop, or PC. This hobby suddenly became popular when many endemic tablet computer. Not just for reading e-books, tablet computers can also be used for internet browsing, watching movies, download and use a variety of applications and games, and much more.

This is one a tablet computers.

How a Sewing Machine Works?

There are many type of sewing machine that available for us to used. Classic sewing machine use our arm and leg to drive it. But now, there are portable electric sewing machine. It driven by an electric motor that controlled with footcontroller.

Both classic sewing machine and portable electric sewing machine uses the similar work principle.

When we push the foot controller, the motor spins and rotate the hand wheel. This hand wheel rotation then cause the needle bar, which bring the needle, go up and down. As looping hook move rotate, and feed dog move back to the top and move forward under surface.

Its movement bring the yarn over needle, then take yarn over the hook carried by the needle to be met orassociated with the yarn, while the feed dogs move the fabric. The meet between the hook and needle under the fabric form stitches.
Electric motors are commonly used on the sewing machine is an asynchronous electric motor

There are two kinds of electric motors:
1. synchronous electric motor, and
2. asynchronous electric motors

Why used asynchronous electric motors?
Because the motor speed can be adjusted by changing the resistance value at the footcontroller. The resulting value of the voltage or current to the motor turns.
The electric motor is connected to the sewing machine hand wheel through a drive belt.

Anomaly of Water

Most matter in state will expand when it is heated. Because it molecular element move faster and need more space. And so does water, it has the same character. Cold water is heavier than warm water, which is why it sinks to the bottom in a container. But whyice cube drift on the surface of a glass of water? Why is it then that the water on the surface of a lake freezes first?

Most matter expands when heated and shrinks again when it cools. But water does not always behave in this normal way, only at temperatures of between its boiling point (100°C) and four degrees Celsius. Below four degrees, or, to put it more exactly, between freezing point (0°C) and four degrees, water expands again when it cools.

This is because it has a higher density at four degrees Celsius than at lower temperatures. And this in turn means that when it cools down to four degrees it becomes increasingly heavy but if it cools down further, up to zero degrees, it becomes lighter again.

And now, when the surface layer of a lake cools down in winter, this water sinks down into the depths. Warmer water rises up and subsequently cools down, too. Colder and warmer water now keep shifting around until the temperature throughout the lake has reached four degrees Celsius. If the water on the surface now cools down even further, it becomes lighter and does not sink down.

At zero degrees Celsius it freezes into ice, whereas the water on the bottom of the lake is still at four degrees. The way that water only shrinks until it reaches a temperature of four degrees Celsius and expands again if it cools down further is known as the anomaly of water and is the reason why it can be warmer at the bottom of a lake than on its surface.

Many animals cannot survive at freezing point, they can attacted by hypoterm or freezed instead. But much of them can still alive at water in four degrees. This anomaly of water is very beneficial for animal that live in deep lake or sea, that the temperatute can less than freezing point.

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Time Traveller Machine

Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the need for the traveler to experience the intervening period (at least not at the normal rate). Any technological device, whether fictional or hypothetical, that would be used to achieve time travel is commonly known as a time machine.

Although time travel has been a common plot device in science fiction since the late 19th century, and the theories of special and general relativity suggest methods for forms of one-way travel into the future via time dilation, it is currently unknown whether the laws of physics would allow time travel into the past. Such backward time travel would have the potential to introduce paradoxes related tocausality, and a variety of hypotheses have been proposed to resolve them, as discussed in the sections Paradoxes and Rules of time travel below.

100 years ago in the journal Annalen der Physik, Germany, appeared an article entitled "Zur Elektrodynamik bewegter Kerper" or "On The Electrodynamics of Moving Bodies". Then this article is more known for proposing a new theory, namely Special Relativity. The author is Albert Einstein, who in 2005  the physics world celebrate it as the Year of Einstein. One hundred years ago it was a miracle year of Einstein. In addition to papers on Special Relativity Theory, he sent two other major papers to the same journal: the photoelectric effect that drove won the Nobel Prize in Physics 1921 and the study of Brownian motion.

Without disparage the other two papers, the work of Einstein's Special Theory of Relativity is the most controversial when it published. And until now, still remained as a subject of discussion. To some scientist, his theory  is the strong foundation to allows the passage of time into the future. Ten years before Einstein came up with the idea, the idea of ​​time travel as written by HG Wells novel : The Time Machine, is a science fiction as opposed to the Law of Physics.

According to the Special Theory of Relativity : space and time are not absolute, but relative. That is, space and time are different for each person. How someone experience thetime and space is depends on two things: where the person is watching and how fast he was moving when compared with the speed of light. Einstein observed that the speed of light is constant at 299 thousand kilometers per second. Speed ​​of light would not be different, though observed by two people from two different observation points. In accordance with the formula, the velocity (v) is the distance (d) divided by time (t). If v is a constant, t and d was the one who should change. One consequence is that the clock is in that condition always moves slower than the clock ticking is still in place.

This leads to the famous "twin paradox". A pair of twins are separated, one of them was rocketed at high speed across the galaxy and come back to earth, the other one live on earth. Although the rocket velocity approaching the speed of light, it took 10 thousand years for the astronauts to explore the galaxy and back to a certain point on the earth. Because of relatively high mobility, the age of astronaut is longer than other his brother who live on earth. Astronauts will return to earth just a few years older than when he slid. Meanwhile, his twin brother had died long ago.

Predictions of a slowdown of time has also been confirmed by experiment atomic clocks flown around the earth with jet aircraft. "If you fly a plane around the earth to the east, you will be 59 nanoseconds younger than if you stay at home,"  Dr. J. Richard Gott said, an astrophysicist at Princeton University, in New Jersey, United States.

The record for this type of travel. He returned to Earth after living in the Russian space station Mir for 748 days. Age younger than the fifth of twelve seconds if he remains on earth.

In his 1905 paper, Einstein also predicted a slowing of time due to the speed of rotation of the earth. Thus, the clock at the Equator thick slower than the clock at the poles. However, this prediction turned out to be wrong.

Recently in an article in Physics Today, Dr Alex Harvey of Queens College in New York and Dr. Engelbert Schucking from New York University confirms that Einstein was not involved in the General Theory of Relativity, which came 10 years later. General Theory of Relativity states that the clocks run slowed more because the gravitational field in which he resides.

A cross between surfing at high speed and the effect of the gravitational field can be applied to future manned missions to the planet Mercury, for example. According to Gott, astronauts who go to the mission for 30 years would save 22 seconds of the life of an astronaut.

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How Solar Cell Works?

Many kind of energy, heat energy, potential energy, kynetic energy, lihgt energy, chemical energy and many other can be converted to another state of energy, directly, or indirectly as well.  A solar cell, also called potovoltaic cell or photoelectic cell is an electrical dxevice in solid state, that can converts the energy of light (photos) directly into electricity. You've probably seen calculators with solar cells, devices that never need bateries and in some cases, don't even have an off button. As long as there's enough ligth, they seem to work forever. You may also have seen larger solar panels, perhaps on emergency road signs, call boxes, buoys and even in parking lots to power the lights.

Although these larger panels aren't as common as solar-powered calculators, they're out there and not that hard to spot if you know where to look. In fact, solar cell which were once used almost exclusively in space, powering satellites' electrical systems as far back as 1958 -- are being used more and more in less exotic ways. The technology continues to pop up in new devices all the time, from sunglasses to electric vehicle charging stations.

The hope for a "solar revolution" has been floating around for decades -- the idea that one day we'll all use free electricity fro­m the sun. This is a seductive promise, because on a bright, sunny day, the sun's rays give off approximately 1,000 watts of energy per square meter of the planet's surface. If we could collect all of that energy, we could easily power our homes and offices for free.

In this article­, we will examine solar cells to learn how they convert the sun's energy directly into electricity. In the process, you will learn why we're getting closer to using the sun's energy on a daily basis, and why we still have more research to ­do before the process becomes cost-effective.

Assemblies of solar cells are used to make solar modules which are used to capture energy from sunlight. When multiple modules are assembled together (such as prior to installation on a pole-mounted tracker system), the resulting integrated group of modules all oriented in one plane is referred to in the solar industry as a solar panel. The electrical energy generated from solar modules, referred to as solar power, is an example of solar energy.

Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, though it is often used specifically to refer to the generation of electricity from sunlight.

Cells are described as photovoltaic cells when the light source is not necessarily sunlight (lamplight,artificial light etc). These are used for detecting light or other electromagnetic radiation near the visible range, for example infrared detectors, or measurement of light intensity.

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Why Did Einstein Sticking Out His Tongue?

Have you seen this picture before? Really often. This is a famous picture of Albert Einsten. He is a famous scientist. Then many question come. Why did he sticking out his tongue? If you think that to be genius, then we must sticking out our tongue and dishelveling our hair. Haha, then try that, tou will looked so freak actually.

Actually it was Einstein's 72nd birthday, March 14th, 1951. It was taken by Arthur Sasse, a photographer. In that original picture, there was Einstein, her wife and Dr Frank Ayedelotte inside the car. Albert Einstein and Aydelottejus got back from his award. Although Einstein was sitting in a car seat, reporters and photographers were still persuing him. The reporters tried to hold Einstein, and Einstein shouted : "it's enough!". But they still asking questions and kept taking picture. When a reporter asked Einstein's willingness to perpetuate photo birthday, eventually he become tired and irritable, and he stuck out his tongue, in a mocking tone.

Neverless, Einstein was very fond of the picture. He cut the image, so it just seemedhe was alone. Then he repreduced the photo and send it to his friends.

Since the scientist had such a repitation for being quirky, the photo was just sees as another example of this irascible charm, and it is becoma one of the famous pictures of Einstein ever taken.

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