The Physics of Skiing

Image from: uk.eurosport.yahoo.com Credit: Reuters

I was watching TV last night about skiing in The Sochi 2014 Winter Olympics (just try Physics behind it.
It was evident that we have energy transformation (from potential to kinetics): 

"As the skier begins the descent down the hill, potential energy is lost and kinetic energy (i.e., energy of motion) is gained. As the skier loses height (and thus loses potential energy), she gains speed (and thus gains kinetic energy). Once the skier reaches the bottom of the hill, her height reaches a value of 0 meters, indicating a total depletion of her potential energy. At this point, her speed and kinetic energy have reached a maximum. This energy state is maintained until the skier meets a section of unpacked snow and skids to a stop under the force of friction. The friction force, sometimes known as a dissipative force, does work upon the skier in order to decrease her total mechanical energy. Thus, as the force of friction acts over an increasing distance, the quantity of work increases and the mechanical energy of the skier is gradually dissipated. Ultimately, the skier runs out of energy and comes to a rest position. Work done by an external force (friction) has served to change the total mechanical energy of the skier." (in Physics Classroom)

 The NSF has a great video about this topic:

I found that all the materials must be design to support bumps and torsion:

"Ski materials have received an equally extensive makeover. Engineers are continually working to make skis lighter and more flexible to absorb bumps in the snow, while keeping them rigid enough to hold their shape during turns. For that reason, metal skis were introduced in the 1950s. Today’s skis, because of their broader tips and tails, have to endure torsional forces that skis of the past could not have withstood. Most skis are now made of sandwiches of fiberglass, wood, aluminum alloys, glue, and polymers." (in Discover Magazine)

They running with a crouch position to reduce drag force:

"A skier maximizes his speed by minimizing resistance to motion, both from air resistance and snow resistance. A skier minimizes his air resistance (drag) by reducing his projected frontal area. He does this by going into a crouch position, which (along with improving his ability to hold balance) results in a lower Real World Physics Problems)

 And they have curved skies to prevent slipping on snow:

"To prevent slipping, the angle ψ must be greater than or equal to 90° . This means that the component of F_R parallel to the plane of the ski, will either be zero (for ψ = 90°), or it will point directly into the snow, towards the right (for ψ > 90°), and the "wall" of snow will prevent it from slipping." (in Real World Physics Problems)

What a great sport!

A step forward to fusion energy

Fusion reactions happens in Sun's core.
Image credit: wikipedia

The ignition is an essential part to make possible a viable alternative source of energy, but has not yet been reached. An important step on the way to the ignition is having the energy generated by energy gains by manipulating the laser to reduce instability in the implosion.
More info: New Observer
Scientific paper: NATURE

Bullet Block Explained!

The question is: which will make the block of wood go higher? The bullet in the center of the block or off center?

Both achieve the same high (conservation of momentum).

There is certainly energy associated with the spinning of the block. The kinetic energy is not conserved during this collision, but the total energy is. The internal energy associated to each block is different (in each block we have thermal energy and deformation energy). So, the block 2 will have the same translational kinetic energy as block 1 by a lower change in internal energy (the bullet causes less thermal energy and deformation to the second block, and it increase in rotational kinetic energy). 

Now, you can see all the info in Wired website, and watch the answer:

New type of heating for ITER

(Phys.org)—Tests for the heating that is to bring the plasma of the ITER international fusion test reactor to a temperature of many million degrees can go ahead from today: After three years of construction, Max Planck Institute for Plasma Physics (IPP) at Garching bei München has officially commissioned the ELISE test rig – the world's largest device of its kind and part of a four-million euro research contract of the "Fusion for Energy" European ITER Agency. Corepiece of the device is an innovative high-frequency ion source developed at IPP. On the ELISE test rig it will now be adapted to the high requirements of ITER.

Read more at: http://phys.org/news/2012-11-elise-iter.html#jCp

ITER (originally an acronym of International Thermonuclear Experimental Reactor) is an international Cadarache facility in the south of France.

More info here: www.iter.org

Read more articles here: ITER

Ultra efficient solar cell

Researchers at Ben-Gurion University of the Negev (BGU) have developed a radically new design for a concentrator solar cell that, when irradiated from the side, generates solar conversion efficiencies which rival, and may eventually surpass, the most ultra-efficient photovoltaics.

Read more at: http://phys.org/news/2012-11-team-side-illuminated-ultra-efficient-solar-cell.html#jCp

Spin cell more efficient than solar flat panels

(Phys.org)—V3Solar has developed a new way to convert the sun's energy into electricity using traditional technology in a new way, and in so doing have discovered a way to get twenty times more electricity out of the same amount of solar cells. Their new device, called the Spin Cell, does away with the traditional flat panel and instead places the solar cells on a cone shaped frame which are then covered with energy concentrators. Once in operation, the whole works spins, making unnecessary the need for tracking hardware and software. What's more, they actually look nice.

Read more at: http://phys.org/news/2012-10-v3solar-photovoltaic-cell-electricity-flat.html#jCp

Mass - Energy equivalence

In Albert Einstein proposed mass–energy equivalence in 1905. The equivalence is described by the famous equation:

where E is energy, m is mass, and c is the speed of light in a vacuum. The equation E = mc² indicates that energy always exhibits relativistic mass in whatever form the energy takes. Mass–energy equivalence does not imply that mass may be "converted" to energy, but it allows for matter to be converted to energy. Through all such conversions, mass remains conserved, since it is a property of matter and any type of energy. In physics, mass must be differentiated from matter. Matter, when seen as certain types of particles, can be created and destroyed (as in particle annihilation or creation), but the system of precursors and products of such reactions, as a whole, retain both the original mass and energy, with each of these system properties remaining unchanged (conserved) throughout the process. Simplified, this means that the total amount of energy (E) before the experiment is equal to the amount of energy after the experiment. Letting the m in E = mc² stand for a quantity of "matter" (rather than mass) may lead to incorrect results, depending on which of several varying definitions of "matter" are chosen.

Einstein was not the first to propose a mass–energy relationship. However, Einstein was the first scientist to propose the E = mc² formula and the first to interpret mass–energy equivalence as a fundamental principle that follows from the space and time.

adapted from Wikipedia

Angry Birds Space: NASA announcement

Angry Birds is a good way to teach Physics. Topics like kinematics (motion, velocity, acceleration), dynamics (force, collisions), and energy are great to learn with that game.
Techradar website explores velocity and distance (post 2);
wired website explores the http://www.wired.com/wiredscience/2011/11/physics-of-the-yellow-angry-bird/

Angry birds presentation

 

View more linhvu28

Angry Birds Space is coming and NASA made "the announcement":

Wireless power could revolutionize highway transportation

Stanford University researchers are developing a technology that uses magnetic fields (shown in red) to wirelessly charge electric vehicles cruising at highway speeds. Credit: Sven Beiker, CARS/Stanford University

A Stanford University research team has designed a high-efficiency charging system that uses magnetic fields to wirelessly transmit large electric currents between metal coils placed several feet apart. The long-term goal of the research is to develop an all-electric highway that wirelessly charges cars and trucks as they cruise down the road.

in PhysOrg

Read the paper at Standford University

Watch the following videos with other concepts:

Piezoelectric materials

Mechanical System



Wind traps

Human activity, solar activity and global warming

A graph of the sun's total solar irradiance shows that in recent years irradiance dipped to the lowest levels recorded during the satellite era. The resulting reduction in the amount of solar energy available to affect Earth's climate was about .25 watts per square meter, less than half of Earth's total energy imbalance. Credit: NASA/James Hansen

A new NASA study underscores the fact that greenhouse gases generated by human activity -- not changes in solar activity -- are the primary force driving global warming.

in PhysOrg

A new NASA study underscores the fact that greenhouse gases generated by human activity -- not changes in solar activity -- are the primary force driving global warming.

"The fact that we still see a positive imbalance despite the prolonged solar minimum isn't a surprise given what we've learned about the climate system, but it's worth noting because this provides unequivocal evidence that the sun is not the dominant driver of global warming," Hansen said.

Hansen's team concluded that Earth has absorbed more than half a watt more solar energy per square meter than it let off throughout the six year study period. The calculated value of the imbalance (0.58 watts of excess energy per square meter) is more than twice as much as the reduction in the amount of solar energy supplied to the planet between maximum and minimum solar activity (0.25 watts per square meter).

According to calculations conducted by Hansen and his colleagues, the 0.58 watts per square meter imbalance implies that carbon dioxide levels need to be reduced to about 350 parts per million to restore the energy budget to equilibrium. The most recent measurements show that carbon dioxide levels are currently 392 parts per million and scientists expect that concentration to continue to rise in the future.

in NASA

NSTX fusion project

"DOE's Princeton Plasma Physics Laboratory (PPPL) is getting an earlier-than-expected start on a $94 million, nearly three-year project as the next stage of its mission to chart an attractive course for the development of nuclear fusion as a clean, safe and abundant fuel for generating electricity.

The project will upgrade the National Spherical Torus Experiment (NSTX) facility at PPPL, over the next 30 months, with completion slated for 2014. The work will enhance the position of the NSTX as the world’s most powerful spherical torus – or tokamak – a device that controls the superheated and electrically charged gases called plasmas that create fusion power."

in PhysOrg

Controlling the plasma is thus a basic goal of fusion research.

ITER aims to produce a sustained fusion reaction in 2020s that will put out ten more energy than is needed to create it.

The NSTX (website) upgrade could also help determine the path to a possible next-generation spherical torus that would produce a burning plasma to complement the output of ITER.

Can NASA give us cold fusion?

In NASA web page there is a video describing the great benefits we will get from NASA LENR research.  Would it be the next domestic energy sources (about 10 kW) based on his E-Cat system (a Low Energy Nuclear Reaction or Cold Fusion energy source)? There's a rumor that it will begging shipping this year. We'll see about that.

font Slashdot

Step forward to control Nuclear Fusion

Using a heating system, physicists have succeeded for the first time in preventing the development of instabilities in an efficient alternative way relevant to a future nuclear fusion reactor. It’s an important step forward in the effort to build the future ITER reactor.

in PhysOrg

Nuclear fusion is an attempt to reproduce the energy like the Sun does in an Earth-based reactor. The gas is heated to several million degrees, and creates a plasma. Sometimes in the plasma, an instability will appear and grow large enough to perturb the plasma. The challenge is to reduce the instabilities deep within in the interior of the plasma so that they don’t amplify, while at the same time allowing the reactor to continue to function normally.

The physicists uses antennas that are used as part of the system to heat the plasma. The simulations and the tests showed that heating and instability suppression can be combined, by aiming the radiation slightly off-center in the plasma.

(Adapted from  PhysOrg )

These improvements can then be implemented in the ITER fusion reactor.

Watch this movie here to know more about ITER.

Check more about fusion.

3-D Photovoltaics Could Revolutionize Solar Power

A revolution for sun panels can begin not in flat panels but in 3D shapes:

The Sun sends some 87 Petawatts of power our way and converting some small fraction of this into usable power is one of the key battlefronts in the fight to free the world from its addiction to oil.

A team from MIT simulated the performance of various shapes and tested several of these on the roof of a building at MIT. Their results indicate that 3D structures can increase the amount of energy that can be generated by a given footprint by as much as 20 times. These structures can also double the number of useful peak hours of generation and reduce seasonal variation to boot.

There are two effects at work. The 3D structure can pick up light when the Sun is at lower angles and internal reflections within the structure help increase the amount of captured light.

in Technology Review

Ref: arxiv.org/abs/1112.3266: Solar Energy Generation in Three-Dimensions

Could Fusion demonstrated

 Image credit: Rossi and Focardi.

Italian scientists claim to have demonstrated cold fusion (w/ Video)
(PhysOrg.com) -- Few areas of science are more controversial than cold fusion, the hypothetical near-room-temperature reaction in which two smaller nuclei join together to form a single larger nucleus while releasing large amounts of energy. In the 1980s, Stanley Pons and Martin Fleishmann claimed to have demonstrated cold fusion - which could potentially provide the world with a cheap, clean energy source - but their experiment could not be reproduced. Since then, all other claims of cold fusion have been illegitimate, and studies have shown that cold fusion is theoretically implausible, causing mainstream science to become highly speculative of the field in general.

The neutrino's saga continues

Physicists wary of junking light speed limit yet
(AP) -- Physicists on the team that measured particles traveling faster than light said Friday they were as surprised as their skeptics about the results, which appear to violate the laws of nature as we know them.

"Going faster than light is something that is just not supposed to happen, according to Einstein's 1905 special theory of relativity. The speed of light - 186,282 miles per second (299,792 kilometers per second) - has long been considered a cosmic speed limit.
The team [...] fired aneutrino beam 454 miles (730 kilometers) underground from Geneva to Italy.
They found it traveled 60 nanoseconds faster than light."

Read entire article here.

The paper in arXiv repository:

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam 

OPERA 

(Submitted on 22 Sep 2011)

The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (60.7 \pm 6.9 (stat.) \pm 7.4 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 \pm 0.28 (stat.) \pm 0.30 (sys.)) \times 10-5.

Subjects:	High Energy Physics - Experiment (hep-ex)
Cite as:	arXiv:1109.4897v1 [hep-ex]

Measuring the impact energy of highly charged ions

Ion Armageddon: Measuring the impact energy of highly charged ions

(PhysOrg.com) -- Much like a meteor impacting a planet, highly charged ions hit really hard and can do a lot of damage, albeit on a much smaller scale. And much like geologists determine the size and speed of the meteor by looking at the hole it left, physicists can learn a lot about a highly charged ion's energy by looking at the divots it makes in thin films.

A schematic detailing the various ways that the energy of highly charged ions is dissipated during an impact. Approximately 60 percent of the ion’s energy is blown back and, according to NIST measurements, 27 percent of the remaining 40 percent goes into deforming the material—making a crater or “divot”. Credit: NIST

Making H2 from solar panel

This is the hybrid system schematic. Credit: Nico Hotz

Hybrid solar system makes rooftop hydrogen

While roofs across the world sport photovoltaic solar panels to convert sunlight into electricity, a Duke University engineer believes a novel hybrid system can wring even more useful energy out of the sun's rays.

"Instead of systems based on standard impurities. The resulting hydrogen can be stored and used on demand in fuel cells."

Read full article in PhysicsOrg.com

Ultimate Energy Efficiency

In magnetic contrast images (top) taken by the Advanced Light Source at Lawrence Berkeley National Laboratory, the bright spots are nanomagnets with their north ends pointing down (represented by red bar below) and the dark spots are north-up nanomagnets (blue). The six nanomagnets form a majority logic gate transistor, where the output on the right of the center bar is determined by the majority of three inputs on the top, left and bottom. Horizontal neighboring magnets tend to point in alternate directions, while vertical neighbors prefer to point in the same direction. Credit: Jeffrey Bokor lab, UC Berkeley

Magnetic memory and logic could achieve ultimate energy efficiency
Future computers may rely on magnetic microprocessors that consume the least amount of energy allowed by the laws of physics, according to an analysis by University of California, Berkeley, electrical engineers.
in PhysOrg