سؤال امتحان فيزياء عن ركلة جزاء راموس بدوري أوروبا

وضعت إحدى الجامعات الإسبانية سؤالا ضمن امتحان بمادة الفيزياء عن ركلة جزاء "سيرجيو راموس"، الأمر الذي أدهش وسائل الإعلام الأوروبية والإسبانية.

وكان السؤال كالاتي: شعر اللاعب «سيرجيو راموس» بالضغط الكبير عندما طُلب منه تنفيذ ركلة جزاء حيث ذهب لتسديد الكرة وكان يبعد عن الكرة مسافة متر واحد ويقف بزاوية 4/180 عموديا.

وقد سدد الكرة بقوة تساوي نصف كتلتها، وكانت سرعة الكرة تساوي نصف قطر الدائرة مع إهمال سرعة الدوران وسرعة احتكاك الكرة بالرياح، احسب حركة ثابت الكرة، وإذا كان المدار الدائري للكرة rt3 على نصف قطر الكرة فهل ينبغي للكرة الدخول إلى المرمى؟".

يذكر أن "ريال مدريد" الإسباني قد خسر في نصف نهائي دوري أبطال أوروبا أمام "بايرن ميونخ" بركلات الجزاء الترجيحية، التي شهدت إضاعة راموس لإحدى التسديدات بطريقة أثارت سخرية وسائل الإعلام بجميع أنحاء العالم.

Physicists store short movies in an atomic vapor

 

 

This is a gradient echo memory setup. The image to be stored, the letter N encoded by a signal laser beam and a mask, enters from the left (pink light) and enters the storage cell filled with Rb atoms. The components of this image will be absorbed by the atoms when, at locations all over the body of the cell, a part of the signal beam and parts of a separate “control” laser beam -- entering from the side (shaded green) via a polarizing beam splitter (PBS) -- and (last but not least) the strength of a magnetic field (delivered by the brown coil around the cell) are just right. The stored image can later be read out and observed with a CCD camera. Credit: NIST

 

 

 

The storage of light-encoded messages on film and compact disks and as holograms is ubiquitous---grocery scanners, Netflix disks, credit-card images are just a few examples. And now light signals can be stored as patterns in a room-temperature vapor of atoms. Scientists at the Joint Quantum Institute have stored not one but two letters of the alphabet in a tiny cell filled with rubidium (Rb) atoms which are tailored to absorb and later re-emit messages on demand. This is the first time two images have simultaneously been reliably stored in a non-solid medium and then played back

.

In effect, this is the first stored and replayed atomic movie. Because the JQI researchers are able to store and replay two separate images, or "frames," a few micro-seconds apart, the whole sequence can qualify as a feat of cinematography. The new storage process was developed by Paul Lett and his colleagues, who publish their results in the latest issue of the journal Optics Express.

One young man was inspired by the lingo of the JQI paper, especially the storage of images in the atomic memory, and contrived a song which he performs on a video clip:

We don't yet need to store grocery barcodes in tiny vials of rubidium. The atomic method, however, will come into its own for storing and processing quantum information, where subtle issues of coherence and isolation from the outside world need to be addressed.

The atomic storage medium is a narrow cell some 20 centimeters long, which seems pretty large for a quantum device. That's how much room is needed to accommodate a quantum process called gradient echo memory (GEM). This useful protocol for storage was pioneered at the Australian National University just in the past few years. While many storage media try to cram as much information into as small a place as possible---whether on a magnetized strip or on a compact disk---in GEM an image is stored over the whole range of that 20-cm-long cell.

The image is stored in this extended way, by being absorbed in atoms at any one particular place in the cell, depending on whether those atoms are exposed to three carefully tailored fields: the electric field of the signal light, the electric field of another "control" laser pulse, and a magnetic field (adjusted to be different along the length of the cell) which makes the Rb atoms (each behaving like a magnet itself) precess about. When the image is absorbed into the atoms in the cell, the control beam is turned off. Because this process requires the simultaneous action of two particular photons---one putting the atom in an excited state, the other sending it back down to a slightly different ground state---it cannot easily be undone by atoms subsequently randomly emitting light and returning to the original ground state. 

That's how the image is stored. Image readout occurs in a sort of reverse process. The magnetic field is flipped to a contrary orientation, the control beam turned back on, and the atoms start to precess in the opposite direction. Eventually those atoms reemit light, thus reconstituting the image pulse, which proceeds on its way out of the cell.

Having stored one image (the letter N), the JQI physicists then stored a second image, the letter T, before reading both letters back in quick succession. The two "frames" of this movie, about a microsecond apart, were played back successfully every time, although typically only about 8 percent of the original light was redeemed, a percentage that will improve with practice. According to Paul Lett, one of the great challenges in storing images this way is to keep the atoms embodying the image from diffusing away. The longer the storage time (measured so far to be about 20 microseconds) the more diffusion occurs. The result is a fuzzy image.

Paul Lett plans to link up these new developments in storing images with his previous work on squeezed light. "Squeezing" light is one way to partially circumvent the Heisenberg uncertainty principle governing the ultimate measurement limitations. By allowing a poorer knowledge of a stream of light---say the timing of the light, its phase---one gain a sharper knowledge of a separate variable---in this case the light's amplitude. This increased capability, at le ast for the one variable, allows higher precision in certain quantum measurements.

"The big thing here," said Lett, "is that this allows us to do images and do pulses (instead of individual photons) and it can be matched (hopefully) to our squeezed light source, so that we can soon try to store "quantum images" and make essentially a random access memory for continuous variable quantum information. The thing that really attracted us to this method---aside from its being pretty well-matched to our source of squeezed light---is that the ANU group was able to get 87% recovery efficiency from it - which is, I think, the best anyone has seen in any optical system, so it holds great promise for a quantum memory."

The lead author of the new Optics Express article, Quentin Glorieux, feels that the JQI image storage method represents a potentially important addition to the establishment of quantum networks, equipment which exploits quantum effects for computing, communications, and metrology. "It is very exciting because images and movies are familiar to everyone. We want to go to the quantum level. If we manage to store quantum information embedded in an image or maybe in multiple images, that could really hasten the advent of a quantum network/internet."

Tecate Group's Ultracapacitor Cells and Modules Ideal for Automatic Meter Reading and Smart Grid Applications

Custom and Off-the-Shelf Devices Provide Maximum Design Flexibility

in Space-Constrained Systems

San Diego, CA, June 9, 2011...Announced today by Tecate Group, A leading global supplier of capacitors and ultracapacitors, is the availability of custom and standard ultracapacitor cells and modules specifically engineered for today's Automatic Meter Reading (AMR) and smart grid applications.  Parts are members of Tecate's UL 810 Recognized PowerBurst®  family, which is comprised of the general purpose TPL and TPLS Series of 2.7V cells, as well as the TPLE Series of 2.3V cells featuring a -40 to +85 degrees C temperature range.  The flat prismatic PC5 and PC10 Series of 2.5V cells are provided for applications where height is limited.  For applications requiring modules, the low- and ultra-low profile PB/PBF/PBL/PBLL Series of 5.0V and 5.4V devices are offered. Parts notably offer OEMs/ODMs the competitive advantage of ensuring product and system safety while minimizing the time and expense associated with additional component-level testing.   To further speed time-to-market, Tecate's customization capabilities include the use of SolidWorks® 3D CAD (MCAD) software to facilitate superior design flexibility, responsiveness, and application engineering support.  The high power density cells feature capacitance values ranging from 0.5F to 400F and low Equivalent Series Resistance (ESR).  Modules withstand over 500,000 cycles.

Ideally suited for use in low profile/small footprint systems and products, Tecate's RoHS-compliant ultracapacitor cells and modules target today's AMR and smart grid applications in which consumption, diagnostic, and status data is collected from water or energy metering devices (gas and electric), and then transferred to a central database for billing, troubleshooting, and analysis. The parts provide battery-free "last gasp" power, and satisfy the high current pulse requirements of AMS technology.  They also provide critical backup power during power outages to ensure uninterrupted communication to/from the grid.  Capable of operating at low temperatures (-40 degrees C), parts supplement batteries for low temperature boost, and relieve batteries of peak power functions to extend batteries' life.

Tecate's PB/PBF/PBL/PBLL/ Series of modules are available with active or passive cell balancing, and with radial leads or flexible wire and connectors to eliminate the need for soldering. They are provided in an array of standard and custom high voltage, advanced circuitry and packaging options to meet application- specific requirements.  For additional information, and to view Tecate's online Ultracapacitor Design Tool, visit,  http://www.tecategroup.com/ultracapacitors-supercapacitors/designtool.php.   To learn more about Tecate's custom modules, visit, http://www.tecategroup.com/ultracapacitors-supercapacitors/custom-modules.php.  

While firm pricing is determined according to customers' specifications, average prices for PowerBurst ultracapacitor modules range from $12.00 to $92.00 in quantities of 50+.  In quantities of 1K, average pricing for 2.3V PowerBurst ultracapacitor cells ranges from $1.25 to $7.75, $7.00 to $17.00 for 2.5V cells, and $1.00 to $19.00 for 2.7V cells.  ARO delivery on standard cells and modules is 8 to 10 weeks.

Caribbean Science Foundation sets sail

Initial investment for the funding agency will come largely from the region’s diaspora scientists, from corporate sponsors, and from development banks.

A week-long trip to the Caribbean in March was more business than pleasure for MIT electrical engineer Cardinal Warde, who spent his spring break courting potential backers for the region’s new science funding agency. The Barbados native is cofounder and interim executive director of the Caribbean Science Foundation (CSF), which launched last fall to promote “the aggressive development of Science, Technology and Innovation” in the tourism-dependent region.

This summer Warde will make stops in London, Toronto, and other enclaves of the Caribbean diaspora to solicit contributions to the $13 million operating budget that the CSF has set for its first three years. “We will put the bulk of our money into entrepreneurial projects,” he says. “We need to pick the low-hanging fruit. The most expedient way forward is for us to let the developed world continue to do the basic research, which is expensive, and we’ll use [that knowledge] to get products to market quickly.”

Other top CSF priorities include reforming the region’s precollege science, technology, engineering, and math (STEM) education curricula and forging collaborations between university researchers and business owners in the Caribbean and abroad. The foundation also plans to dole out academic scholarships and to develop STEM education outreach efforts such as science fairs, TV programs, and exhibitions.

Ripe for high-tech R&D 

 

Funds for the CSF will be directed to projects in member states of the Caribbean Community (CARICOM), the regional political alliance that comprises Haiti, Guyana, Suriname, Belize, and the 11 independent English-speaking island nations of the West Indies. Bound by a shared history and culture, CARICOM countries also share a postsecondary educational infrastructure built around the University of the West Indies (UWI), which has campuses in Jamaica, Trinidad and Tobago, and Barbados. In recent years CARICOM has also been moving toward a single-market, single-currency economy.

Warde says the Caribbean region is ripe for high-tech R&D in drug development that exploits the region’s rich biodiversity; renewable energy, given the area’s high exposure to the Sun and to trade winds; and information technology. “There’s no reason why Google couldn’t have been invented in Barbados,” he says. “It doesn’t take a lot of resources, manpower, or heavy equipment to start a software company.”

Instead of relying on government support, the CSF will seek investment from regional development banks and from an organization that is mobilizing the 75–80% of college-educated professionals the World Bank estimates were born in the region but are living and working elsewhere. The Caribbean Diaspora for Science, Technology, and Innovation (CADSTI) was created in 2008 by Warde, other diaspora scientists, and scientists in the region. In addition to money, CADSTI will also provide technical and business advice to Caribbean researchers and entrepreneurs. Membership won’t be limited to individuals born in the Caribbean, says Warde. “Anyone who wants to help” can join.

Businesses like Welectricity, based in Saint Vincent, will be eligible for the 15–20 “phase one” grants that Warde says will be offered once the CSF raises its first $1 million. Welectricity’s social Web tool, which tracks energy usage in the home, won a Best Idea for the Millennial award in the GE Ecomagination Challenge last year. In addition to capital, Caribbean entrepreneurs need access to external experts and markets, says Welectricity founder Herbert Samuel, who belongs to the Caribbean Research Innovation and Entrepreneurship Network, an online community with more than 400 members. “[We’re] isolated from a lot of things that are needed at the critical early stage—adequate funding, suitable technical resources, and a significant network of enthusiastic early adopters and evangelists.”

Trinidad and Tobago native Nicholas Fuller, a physicist at the IBM Thomas J. Watson Research Center in New York, says he’s interested in serving as a CADSTI consultant on the implementation of solar panels. “I think there’s a lot more we could be doing to optimize the efficiency of solar farms in one or more locations in the Caribbean.” Fuller volunteers as a mentor for the UWI–IBM research scholars program, which annually selects an undergraduate student from UWI’s electrical and computer engineering departments for a summer internship at IBM.

Stephon Alexander, a cosmologist at Pennsylvania’s Haverford College who also hails from Trinidad and Tobago, says the launch of the CSF and CADSTI has inspired him to revisit plans he drafted 10 years ago for a Caribbean theoretical sciences institute modeled after the Institute for Advanced Study in Princeton, New Jersey. “It’s cheap to do that kind of science,” says Alexander.

“The real Achilles’ heel for the Caribbean [countries] is that they don’t have enough scientists on the ground,” says Khotso Mokhele, former president and CEO of South Africa’s National Research Foundation. It was a 2006 report commissioned by the United Nations Educational, Scientific and Cultural Organization and CARICOM and authored by Mokhele that catalyzed the formation of the CSF. “The Caribbean diaspora is so huge that [CADSTI] could make a major contribution to science and technology in the region if they properly organize themselves,” says Mokhele. But the university system, especially graduate research, also needs more support from the region’s governments, “or the [diaspora] model won’t work,” he says.

One-legged stool

Regional universities and other existing scientific organizations can help get the CSF off the ground, says Harold Ramkissoon, a UWI professor emeritus of applied mathematics who also cofounded the CSF and sits on its board. For example, “If CSF gets funding for science education projects, it could delegate [coordination of those projects] to Cariscience [a network of the region’s university research departments] or the Caribbean Academy of Sciences,” he says. The CSF has offered a spot on its board of directors to the Caribbean Council for Science and Technology, which coordinates CARICOM’s science and technology policies.

Warde says he hopes to meet with the CARICOM heads of state to present his case for the CSF as a means of diversifying the region’s economy. “Our economies in the Caribbean are like a stool with one leg,” says Warde. Countries like Brazil and Singapore “are eating our lunch. They’re gaining market share by developing advanced devices and products that are based on science and technology, and I think it’s time we do something about that.”

Jermey N. A. Matthews

Recent Noteworthy Physics Papers

The aim of this thread is to highlight recent (as in within the past 3 months) noteworthy physics papers that have been published in peer-reviewed journals. Anyone can post here, subject to the guidelines listed below:

1. Papers must be from respected peer-reviewed journals. This includes Nature, Science, Physical Review Letters, The Physical Review Journals, European Physical Review, Europhysics Letters, Physics Letters, Applied Physics Letters, and Journal of Applied Physics.

2. Provide the full reference to the paper. If the paper also can be found on the web without requiring subscription (such as on the e-print ArXiv), please provide the url. In any case, the full reference to the paper in the journal must be provided. The format for the reference should be as follows:

First Author's Name et al., Journal Name, Volume number, Page/Article number, (Year).

3. Provide the full abstract to the paper. This is not necessary if the paper is also available for free on the web.

4. [Optional] Please write a brief description why you are highlighting this paper, and why it is noteworthy.

5. [Optional] If this paper is also highlighted by other services, such as AIP's Physics News Update or ScienceDaily, please provide the link to those highlights. This can be added later as they are found.

6. This thread is only meant for highlighting the paper, not as a discussion thread. Please create a different thread if you think the paper deserves some discussion or comments.

Work done by load in charging a capacitor

The energy stored on a charged capacitor is  0.5*Q*V  or  0.5*C*V²  .

BUT

what is the electrical work done by the supply as it transfers the charge to the capacitor?

I have heard two answers:

 
W=QV       and      W=0.5*QV

the first answer implies, i think, that energy is required to move charges against the already present charges on the capacitor plate. is this correct ?

Capacitors

Capacitors are the elements of other electronic items and Oziguetha core is controlling the flow of electric charge in the electronic circuit.
Balmktv called because it Efum intensify and keep within the shipment such as real-time battery 

Contains intensive two surfaces separated from each other deliverers insulation and is connected with the parties intensive surfaces ..
Just reached the outskirts of the intense flow of electric charge and accumulate on the surface of the board positive charges on one plate and negative on the other, and so that both shipments are trying to cross the barrier separating the shipment are attracted to other
Panels will remain intense for a short time Kalptaria
Charging current depends on the value of intensive resistance connected to him

The key factors that affect the capacitance:

1 - the size of the surface area of ​​the condenser plates
Other words, the capacitance is directly proportional to surface area of ​​the plates if the board has increased the surface area of ​​Zadeh capacitance so as to increase their capacity for electric charge and vice versa less capacitance, the less this space.
2 - the distance between the plates
Carrying capacity when the distance between the panels Tzmad and increases as the distance that I said that there is no inverse proportion between the capacitance between the anointing and Oasis
3 - center separation
Capacitance measured in farad proportion of the world of physics, chemistry, English, Michael, born in 1791 Vardae.

Types of capacitors
1 - intensive chemical
2 - intensive Alsermiki
3 - Variable Capacitors
4 - Capacitors Slide

Since the farad is a value to a very high lateral capacity Vnstkhaddm intensive parts of the expression of the farad capacitance Kaalmicrawfarad or nano or pico .