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Physics Note
Try our new section to study physics... Are you a student in a physics class? • See our Physics homework help section.
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Physics
The Physics Classroom is an online interactive tutorial of basic physics concepts. The lessons use an easy-to-understand language to present common physics ...www.physicsclassroom.com/ - 6k
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Eric Weisstein's World of Physics
Online encyclopedia of physics terms and formulas. Full searchable, and also browsable alphabetically and by topic. Part of Eric's Treasure Troves of ...scienceworld.wolfram.com/physics/ - 9k - Simpanan sementara - Laman-laman serupa
Physics 2000
An interactive journey through modern physics. Have fun learning visually and conceptually about 20th century science and high-tech devices.www.colorado.edu/physics/2000/ - 2k - Simpanan sementara - Laman-laman serupa
Physics The WWW Virtual Library
Resources pertaining to the physics of sound, noise control and soundproofing. ... An actively maintained collection of space physics links. ...vlib.org/Physics - 9k - Simpanan sementara - Laman-laman serupa
Physics - spotlighting exceptional research
Let us know what you think of Physics. Please email physics@aps.org with your comments, ideas, or suggestions for topics. You may wish to consult our FAQ ...physics.aps.org/ - 20k - Simpanan sementara - Laman-laman serupa
physicsworld.com
Physics news, jobs, equipment buyer's guide, and events.physicsworld.com/ - 34k - Simpanan
How to Keep Your Computer Safe From Viruses
UNDERSTANDING PHYSICS.
Look outside the window and you may see the leaves of a tree falling down.
There will some students who would not even have noticed the leaves falling. Some may have seen the falling leaves but this not register what they saw. Other may admire the beauty of the falling leaves .
Still others may ask some questions about the falling leaves;
• Why did the leaves fall down and not to fly up ?
• Would the larger leaves fall faster ?
• Would a heavier leaf fall faster?
In fact there are a thousand and one questions you can as about the falling leaves.
The leaves of a tree falling down is one of the events that happened around us everyday
Event –something that happens, in this case the leaves falling from the tree. An action, with a beginning and an end.
Physical phenomena are always unfolding before us. By asking questions we can focus on the aspect we are interested in. By making observations and careful measurements we can gather the necessary data that will help us in our search for the answers to our question. Experiment have to properly planned and carried out to verify the answer we seeks.
In physics we learn about making connections. We know that when released the object,it fall down towards the earth. We observe that the Moon goes round the Earth. Is there any connection between the two phenomena ?
Physics is a branch of science centered on the study of the matter, energy, and the connection between them.ExampleThree students have performed an experiment in which they tested the sinking and floating behavior of three objects , each of the same volume but of difference mass. They found two of the object sank while the third object floated. Consider the following discussion among them.
Q. Why should I have to study physics if I'm going to be a doctor - lawyer - etc?
Physics, as a discipline - especially at an undergraduate level, teaches many things that are important in all walks of life:
1) Problem Solving skills - the typical physics course is more problem solving based than any other subject (except perhaps mathematics) and the problems are often more practical. If you want to be a doctor, say, skill at quickly thinking about the problems of "what is wrong with this patient" could mean the difference between life and death.
2) Real World Familiarity - Freshman physics courses tend to teach about the every-day, real, world. You learn about how things move, how they fall, what friction means, what constraints conservation of energy and momentum can put on a system.
3) Relevant information - Physics is directly relevant to the core of many fields which might seem separate at first glance.
Engineers build bridges, but they need to understand the forces involved and how bridges react to stress in order to build safe ones.
Biologists look at proteins and DNA - the structures of which are measured using diffraction techniques developed by physicists, and only really understood through physics. Biologists also use light and lasers to make fluorescence measurements to keep track of the chemicals present - physics illuminates the devices, lenses, microscopes and the very colors of the dies used!
As you can see, there are many good reasons to study physics, no matter what your career goal might be - but the most important is that physics is constantly unveiling new facts about our universe - from the very small, like new semiconductors and superconductors, to the very large, like black holes and galaxies - do you want to understand what is coming, or do you want to be left behind?
The Oceans' Wave Power
For more than 200 years inventors worldwide have filed patents for wave-power technology of a dazzling variety of designs-bobbing objects ("ducks"), buoys, articulated rafts, floating bags, overspills, and many others. There has been no shortage of ideas. Many of these ideas are in fact technically feasible, so it seems a shame that this renewable energy resource has not been much used. The main challenge is building a system that is economically attractive when so many other forms of energy production (nuclear, fossil fuels) receive subsidies and already have infrastructure in place. There are some wave power systems in place around the globe: the Faroe Islands; Islay, Scotland; Oahu, Hawaii (providing power for the U.S. Marine Corps. base there); Santo, Spain; Portugal; and even the world's first commercial "wave farm" in England.
The World Energy Council has estimated that wave power could produce as much energy in a year as 2,000 oil, gas, coal and nuclear power plants' twice the amount of electricity produced worldwide-by generating as much as 2 terawatts (that's 1 trillion watts).
Not every place is a candidate for wave power generation. Prime locations identified are Scotland, northern Canada, southern Africa, and the Atlantic Northeast and Pacific Northwest of the United States. Experts have estimated that wave-power systems in the Pacific Northwest alone could generate up to 70 kW per meter of coastline.
Typical Designs
Wave-power systems can be located onshore or offshore, and come in a surprising range of designs. There are currently four basic "capture" methods: point absorbers (largely vertical, with a relatively small footprint on the surface); attenuators (horizontal footprint, arranged parallel to the waves to undulate with the flow); terminators (perpendicular to the waves); and overtopping (perpendicular to the waves, which break over the system). There are different power take-off systems including hydraulic ram (water hammer pumps water above the starting point); elastomeric hose pump (peristaltic, like your intestinal tract), pump-to-shore, hydroelectric turbine, air turbine, and linear electrical generator. Here are some systems already in operation, or close to it:
OFFSHORE: POINT ABSORBER SYSTEMS
1. The Salter "Duck"-In 1970 Stephen Salter ("the father of wave power"), a professor at the University of Edinburgh, designed a wave-power device that could both stop 90 percent of the wave motion and convert 90 percent of that into electricity, a standard that all other designed continue to be measured against. Ironically, the Duck itself never went into use. During the 1990s, a project based on the Duck and dubbed the OSPREY (Ocean Swell Powered Renewable Energy), commenced in the Clyde Estuary of the Scottish coast. Capable of generating 1 mW of power, the OSPREY was on its way to becoming an unqualified success until Hurricane Felix came along and sunk it (at great expense in terms of both money and confidence).
2. The AquaBuOY wave energy device-AquaBuOYs (Finivera Renewables) really do look like navigational buoys, and this is no coincidence. Obviously, maximum output from a wave-power device should be during those times when the waves are at their highest, but if the technology can't withstand rough seas (as with the OSPREY, above), they aren't much good. Operating on the premise that since navigational buoys can survive for decades in all sorts of conditions, the AquaBuOYs were designed to ride the waves for an estimated 100 years. The vertical wave action drives a two-stroke hose pump that directs pressurized seawater into a turbine connected to a generator; the resulting power is sent via an underwater transmission line. While at least four projects are in the permitting process (including one in Makah Bay, WA), as of this writing.
3. PowerBuoy "Like the AquaBuOY above, the PowerBuoy resembles a navigational buoy, although one with long cylinder extending far below that houses the mechanics of the system. These PowerBuoys (Ocean Power Technologies) are placed from one to five miles offshore in 100 to 200 feet of water, and can be ganged together to form a "wave-power farm" such as the one to be installed off the coast of Santo, Spain. That 1.39MW station will have one 40kW and nine 150kW PowerBuoys.
OFFSHORE: ATTENUATOR SYSTEMS
1. Pelamis - Ocean Power Delivery, Ltd., developed world's first commercial offshore wave-power facility using its Pelamis Wave Energy Converter, a string of steel cyclinders hinged to articulate. It lies half-submerged, like a 150-meter-long, bright red sea snake (pelamis is the genus for the sea snake), more or less facing into the waves. The cylinders contain hydraulic pumps activated by the wave action; the electricity comes as high-pressure oil gets pumped into generators. The first phase of the wave farm, located 5 km off the coast of Portugal, comprises three 750kW Pelamis "snakes" that combined to generate 2.25 MW; another 28 are expected to be added, bringing the total power generated to 22.5 MW'enough to provide electricity for more than 15,000 homes.
OFFSHORE: TERMINATOR SYSTEMS
1. Nearshore OWC-This is an offshore version of the Limpet, described below.- OFFSHORE: OVERTOPPING SYSTEMS
1. Wave Dragon-Overtopping systems work very much like hydroelectric dams, using the potential energy of water stored at an elevation higher than the turbines it drives. The Wave Dragon overtopping system funnels the waves into its own reservoir to create a head; the water is then released through channels that contain turbines. The Wave Dragon is moored 25 to 40 meters offshore in deep water, somewhat like a floating beach.
ONSHORE: OSCILLATING WATER COLUMN:
1. Limpet (Land Installed Marine Powered Energy Transformer)- This an oscillating water column (OWC) system to convert the waves' kinetic energy to electrical power. Picture a box with the open end submerged but slightly tilted toward the incoming waves, with air trapped inside the box. Now imagine there is a narrow outlet for this air, and inside this tube is a turbine. As the waves raise the level of the water inside the box, the air rushing in and out of the tube powers the turbine. A Limpet system (WaveGen) in Islay, Scotland, uses an inclined oscillating water column (OWC) system optimized for the area's anverage annial wave intensity, and feeds a pair of 250kW generators. The Limpet power station in the Faroes is very similar. WaveGen also designs a near-shore oscillating water-column system.
There are many companies designing wave-power systems using these and other designs (such as the tapered channel system, an onshore system, and the pedulor system, an offshore device), and new ones seem to come along frequently as more countries come to recognize the potential of wave power.
Wave Power Advantages
1. Wave energy is an abundant and renewable resource. 2. Even though not every country has coastline, the combined potential output of wave-power generation would meet all the electricity needs of the world. 3. Although the equipment represents a substantial investment, the "fuel" is free and not confined by geopolitical boundaries. 4. The effect on the environment is deemed to be minimal.
Wave Power Disadvantages
1. These are most effective near coastlines, of which there is a finite supply. 2. Large scale systems are still in the early stages.
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Science discovery- used physics to build a flying machine
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt3IlqVH5-ialCLAF60uwxCDDQ4-dsniPqmc_wa9m9bV4ttwGyKeote9t0SkhrQobP7uWdlzdApjffJyOk-eysAW9JwUtHzYY6E91S2TWmNQxE45rRlfRsOEjKTNN76vk2E_UXza-NSL9I/s320/The+world+1_0001.jpg)
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petrol engines of the time, built for the early motor cars, were too heavy for an aircraft. Over the following years they built improved
versions of the Flyer and made longer flights.
History of Computer
Supercomputers A supercomputer must work so fast that its main processing and memory circuits are supercooled to many degrees below freezing. Supercooling reduces the resistance of the conductors in the electronic circuits.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMMDKUzSvTW2ErVU-39bKk99Wtnu1TVHQXib6wsttt7LMSES4fTkPuq_f2IiRKdQfqBzj2rW6RX809gFF_046FMgOyPu27brnSAQEdBRpVqjotqBqnisxceK8vQRsDUTaCx80-RmCgzytQ/s320/mis_0001.jpg)
In the 1830s English mathematician Charles Babbage (1792-1871) designed several kinds of programmable mechanical calculators. His machines used gearwheels to do the calculating and had more than 2,000 moving parts. Due to engineering and money problems, Babbage's machines were never finished at the time. But modern computers still use his basic ideas.
Physics Teacher - Electricity Network
place, as a flowing current. Electricity is so useful to us because it can flow along wires to
wherever we need it, and be changed into other forms of energy such as light, heat and movement.
The electricity network
Power stations turn the energy of movement into electrical energy which is medium strength, or mid voltage. This is changed into more powerful, high-voltage electricity and sent along large cables or wires, high on pylons or buried underground. This network of cables and wires is called the electricity distribution grid. The electricity is changed back into lower-power forms, industrial and mains voltage, for use in factories, farms, offices and homes.
Electricity in atoms
Everything is made up of trillions of incredibly tiny particles, called atoms. An atom has a central nucleus containing protons, each with a positive charge, and neutrons, each with
no charge, or neutral. Going around the nucleus in empty space are much smaller particles, called electrons, each with a negative charge. When atoms or substances gain or lose electrons, they become electrically charged. Gaining electrons makes them negative. Losing electrons makes them positive.
Electricity at work
If there was a power cut in this city, people would have to manage without most of their lighting and heating, and the machines that make their lives so much easier. Daily routine would grind to a halt and the only sources of energy would be batteries, candles, wood, coal or gas. Yet people managed without electrical devices for thousands of years, and still do in many parts of the world. It is only in the last century or so that electricity has been put to work. One of its great advantages is that it is available at the flick of a switch.
Physics Tips For SPM 2008
Chapter 1 : Sub-topic - Measure instruments
Chapter 2: Sub-topic - Momentum, impulse / impulsive force and Forces in Equilibrium
Chapter 3 : Sub-topic- Gas Pressure -atmospheric pressure and Pascal's Principle
Chapter 4: Gas Law - Experiment Heat Capacity/ latent heat/ Thermometer
Chapter 5: Refraction of light/ understanding lenses
Chapter 6: Interferens of Waves
Chapter 7: Ohm law, Relationship between I and V
Chapter 8: Electromagnetic Induction/ Application
Chapter 9: LOgic gates and Semiconductor diodes
Chapter 10 : Radioactive and Isotop/ Nuclear Energy - Nuclear Fusion
Science Discovery
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUtneJCyoPDRAswT6LKF_31aYMbV2Cu3EXJiUz5LalEVoe07KrpB2t04DQaOdBwTqdN9udU4TJo5EOAuktbYXcSYAGITs7sXZ-0owVOULJL7Qf3aEnB3gisOUTb4DBzkSDIVamnAtpLjRn/s320/Discovery+1_0001.jpg)
Composites
Space tiles- the tiles on the undersides of space shuttles are made of heat-resistant ceramic composites. As the shuttle comes back from space into the Earth’s atmosphere, friction with the thickening air generates enormous heat. The tiles keep this heat out of the shuttle’s interior. They are checked and renewed as necessary after each mission.
Strong as steel…most valuable metal
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjs5cFRXcyL_omE1zRkKiS4uo4Sf0TvABHEZfNl26haLq9NplpkExR6XsxZ82WpytTVIcyXfAGSqlbj4SAhUZLSgZhnTTOsC-j_L-h5156fNG3LStLhUecDWDOvuo9h-Iiv8vzFCs26FSIm/s320/Gold_0001.jpg)
Keyword : Physics Teacher's, Trial Exam
Floating ice
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv7QbyCDy6L6YPpp9FTlfwLbmUfrlfjSDsdpQcUngW3LmabvCrhIGStu_Y4G7SOAmYd1RN_B8f4OG5SFAK6gQwhEUe8FjKucbyjBVVT4VEVj38t2abwztioamCce8GNqmlHw7rTgJ8JljE/s200/ice_0001.jpg)
Energy from the Sun
High and Low Sounds
the bass drum's deep boom is low-pitched, while the triangle's shrill tinkle is high-pitched. Pitch depends on how many times the sound source moves to and fro, or vibrates, each second. This
is the same as the frequency - how many sound waves are produced each second. The frequency of a wave is measured in units called Hertz, Hz. For example, the note of middle C, in the
middle of a piano keyboard, has a frequency of 261 Hz. Frequency is related to wavelength, since higher frequencies have shorter waves. The length of a middle C sound wave is 126 centimetres.
We hear many sound frequencies, from the shrill notes of bird song to the deep growl of traffic. But, because of the way our ears work, we do not hear all of the sounds around us. Our ears pick up frequencies from about 20 to 20,000 Hz (Hertz, vibrations per second). We hear sounds below 80 Hz as low, deep booms, thuds or rumbles. Frequencies below about 30 Hz may not be heard clearly, but if they are powerful enough, we can feel them as vibrations in the air and ground. Our ears are most sensitive in the range from 400 to 4,000 Hz. (Human speech tends to be around 300-1,000 Hz.) Sounds above about 5,000 Hz are extremely high-pitched squeaks, hisses and screeches. As people get older, their ears become less sensitive to high notes. So a young person can hear a bat's very high-pitched squeaks, while an older person cannot.
Telecom network
Inside a mobile phone
A "mobile" is a low-power radio transmitter-receiver. It has mouthpiece to change sound waves into electrical signals (like a microphone), and an earpiece to change electrical signals into sound waves (like a loudspeaker). The transmitter-receiver only needs to send and pick up waves from the nearest cell tower, which is usually just a few kilometres away. However hulls or tall buildings may block the radio signals. also, in areas where the cell towers are farther apart, the signals may be too weak to travel to and from the phone.
Simple Machines
Building the pyramids
The pyramids were built in ancient Egypt about 4,500 years ago, from thousands of blocks of stone-some weighing many toones. These may have been levered into place, or dragged up a slope built beside the pyramid, or rolled up on logs. No-one really knows.
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