Kirchoff’s laws
Kirchhoff’s laws are rules for understanding the behavior of electric current (I) and potential difference (V) in electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff.
They are widely used in electrical engineering and physics; we’re studying them in class now. The ideas behind them can be found in chapter 35 of Conceptual Physics (Hewitt/Pearson) Here is Kirchoff’s voltage law:
Our presentation on this topic is here
https://kaiserscience.wordpress.com/physics/electromagnetism/electric-currents/
Are we consuming too little salt?
…Cutting back on salt can reduce blood pressure, but often, the change in blood pressure is small. According to the American Heart Association, a person who reduces salt intake from median levels (around 3,400 milligrams ) to the federal recommended levels (no more than 2,300 mg) typically sees a slight drop of 1% to 2% in blood pressure, on average.
Also, other factors affect blood pressure. For example, blood pressure increases with weight gain and decreases with weight loss. So, keeping a healthy weight can help prevent high blood pressure. Eating foods high in potassium also seems to counter some of the effects of high salt consumption on blood pressure.
Studies comparing salt intake in different countries worldwide have not found a clear connection between salt intake and high blood pressure. Societies that eat lower levels of salt do not necessarily have less heart disease than those that eat a lot of salt.
…Surprisingly little is known about how much salt we need. U.S. residents consume, on average, about 3,400 milligrams of salt per day. For decades, the U.S. government and organizations, such as the American Heart Association, have recommended people consume less salt. Current dietary guidelines recommend no more than 2,300 mg of sodium—about a teaspoon of salt—per day for teens and adults. No more than 1,500 mg per day is recommended for groups at higher risk of heart disease, including African Americans and everyone over the age of 50.
The U.S. dietary guidelines were established in the 1970s when relatively little information was available about dietary salt and health. The guidelines were the best guess, given the information available at the time. …
Some scientists now say that the average amount of salt U.S. residents eat (3,400 mg of salt per day) is safe and may even be healthier than the lower government guidelines.
In fact, a study found that people who meet the U.S. recommended limits for salt (2,300 mg of sodium per day) have more heart trouble than those consuming more salt. This study included approximately 150,000 people from 17 countries and was published in the New England Journal of Medicine.
Scientists challenging the current guidelines say people should consume at least 3,000 mg of salt per day and up to 6,000 mg per day. The new research results suggest a low-sodium diet may stimulate the production of renin, an enzyme released by the kidneys. Renin plays a role in regulating the body’s water balance and blood pressure. Too much renin may harm blood vessels, and a high-sodium diet would help lower the amount of renin produced….
Electric Field Hockey Virtual Lab
click here: Electric Field Hockey Virtual Lab
Play hockey with electric charges. Place charges on the ice, try to get the puck in the goal. View the electric field. Trace the puck’s motion.
Learning Goals
Determine the variables that affect how charged bodies interact.
Predict how charged bodies will interact.
Describe the strength and direction of the electric field around a charged body.
Gravitational waves
Astrophysicists may finally have discovered gravitational waves
In TechInsider, Dave Mosher writes:
Gravitational waves may have been detected for the first time, but we won’t know for sure until February 11, 2016 — when scientists will either confirm or dispel the rumors, sources close to the matter tell Tech Insider.
Detection of gravitational waves would be unprecedented. Whoever finds them is also likely to pick up a Nobel prize, since the phenomenon would confirm one of the last pieces of Albert Einstein’s famous 1915 theory of general relativity.
Confirming they exist would tell us we’re still on the right track to understanding how the universe works. Failing to find them after all these years might suggest we need to revisit our best explanation for gravity or rethink our most sensitive experiments, or that we simply haven’t looked long enough.
“Gravitational waves are ripples in the fabric of space-time, predicted by Einstein 100 years ago,” Szabi Marka, a physicist at Columbia University, told Tech Insider. “They can be created during the birth and collision of black holes, and can reach us from distant galaxies.”
Black holes are the densest, most gravitationally powerful objects in existence — so a rare yet violent collision of two should trigger a burst of gravitational waves that we could detect here on Earth.
Colliding neutron stars and huge exploding stars, called supernovas, are thought to generate detectable gravitational waves, too.
However, any sort of signal has eluded the planet’s brightest minds and the most advanced experiments for decades. Until now — maybe.
Columbia University in New York City is hosting a “major” event the morning of Thursday February 11, 2016, a source who is close to the matter, but asked not to be named, told Tech Insider.
Another source also confirmed the event but downplayed the significance of the event as anything “major.”
Regardless, several physicists and astronomers with expertise in gravitational wave science are scheduled to attend.
The topic? The latest data from the Laser Interferometer Gravitational-Wave Observatory (LIGO), a $1 billion experiment that has searched for signs of the phenomenon since 2002.
LIGO has two L-shaped detectors that are run and monitored by a collaboration of more than 1,000 researchers from 15 nations, and Marka is one of them.
Marka said that he and his colleagues have worked in the field for more than 15 years and that “these are very exciting and busy times for all of us.”
He also said that Advanced LIGO, an upgrade that went online in September 2015, finished a period of hunting for gravitational waves on January 12, 2016. (That was one day after we saw the first alluring rumors of detection.)
Both LIGO instruments are L-shaped arrays of lasers and mirrors that should be able to detect gravitational waves. Szabi Marka compared them to a pair of giant ears that can “hear” the spacetime ripples that result from black hole mergers, or some other catastrophic event in space. The closer a collision is to Earth, the “louder” the signal should be.
LIGO’s hearing is sensitive enough to detect mind-blowingly small disturbances of space, “much smaller than the size of the atoms the detector is built of,” he said. PhD Comics says LIGO’s level of sensitivity is “like being able to tell that a stick 1,000,000,000,000,000,000,000 meters long has shrunk by 5mm.”
Put another way, detecting a gravitational wave is like noticing the Milky Way — which is about 100,000 light-years wide — has stretched or shrunk by the width of a pencil eraser.
It would be no wonder why it has taken researchers so long to find gravitational waves; it’s terribly difficult work. (Even a truck driving on a nearby road can disturb LIGO, despite the instruments having state-of-the-art vibration-dampening equipment.)
It would also be no wonder why scientists might try to stay tight-lipped about the discovery yet “suck at keeping secrets just like everyone else,” as Jennifer Ouellette wrote at Gizmodo.
But at this point, there’s only one way to know for sure if the latest rumors are true: Wait until Thursday.
Einstein’s wildest prediction could be confirmed within days: Tech Insider
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When Einstein’s General Relativity was first proposed, it was incredibly different from the concept of space and time that came before. Rather than being fixed, unchanging quantities that matter and energy traveled through, they are dependent quantities: dependent on one another, dependent on the matter and energy within them, and changeable over time. If all you have is a single mass, stationary in spacetime (or moving without any acceleration), your spacetime doesn’t change. But if you add a second mass, those two masses will move relative to one another, will accelerate one another, and will change the structure of your spacetime. In particular, because you have a massive particle moving through a gravitational field, the properties of General Relativity mean that your mass will get accelerated, and will emit a new type of radiation: gravitational radiation.
This gravitational radiation is unlike any other type of radiation we know. Sure, it travels through space at the speed of light, but it itself is a ripple in the fabric of space. It carries energy away from the accelerating masses, meaning that if the two masses orbit one another, that orbit will decay over time. And it’s that gravitational radiation — the waves that cause ripples through space — that carries the energy away. For a system like the Earth orbiting the Sun, the masses are so (relatively) small and the distances so large that the system will take more than 10^150 years to decay, or many, many times the current age of the Universe. (And many times the lifetime of even the longest-lived stars that are theoretically possible!) But for black holes or neutron stars that orbit each other, those orbital decays have already been observed.
We suspect there are even stronger systems out there that we simply haven’t been able to detect, like black holes that spiral into and merge with one another. These should exhibit characteristic signals, like an inspiral phase, a merger phase, and then a ringdown phase, all of which result in the emission of gravitational waves that Advanced LIGO should be able to detect. The way the Advanced LIGO system works is nothing short of brilliant, and it takes advantage of the unique radiation of these gravitational waves. In particular, it takes advantage of how they cause spacetime to respond.
What Will It Mean If LIGO Detects Gravitational Waves? – Forbes
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Detection range of AdvLIGO
LIGO and Gravitational Waves: A Graphic Explanation
NOVA Absolute Zero
View online: Nova – Absolute Cold
View online (link 2): Nova – Absolute Cold
Air-conditioning, refrigeration, and superconductivity are just some of the ways technology has put cold to use. But what is cold, how do you achieve it, and how cold can it get? We follow the quest for cold from Cornelius Drebbel up to Michael Faraday.
extra! Milestones in cold research and extra! Anatomy of a refrigerator
official website NOVA: Absolute Zero
Transcript (for easy reading) of the show
Questions: please answer the following in complete sentences, demonstrating that you understand the concepts involved.
In this show Andrew Szydlo, a well known chemistry professor, enjoys re-enacting the work of the great court magician & chemist, Cornelius Drebbel, 1600’s France.
1. How did Drebbel (likely) create the world’s first demonstration of indoor air conditioning?
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Robert Boyle, famous for his study of gas, temperature and pressure. He systematically worked through a series of ideas about what cold is: Please answer:
2. Does cold come from the air? Is cold transferred by “frigorific” cold-making particles? If not, what does cold come from? How did Boyle show that “cold” was probably not a material?
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The first temperature scale to be widely adopted was devised by Gabriel Daniel Fahrenheit. He was a gifted instrument maker who made thermometers for scientists and physicians across Europe.
3. How did he set his lowest temperature? How did he set his other reference temperatures?
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In terms of temperature, is there an absolute lower limit? The idea that there might be one, would become a turning point in the history of cold. The story begins with the French physicist Guillaume Amontons. He was doing experiments heating and cooling bodies of air to see how they expand and contract.
4. How did Amotons realize that there must be a lowest possible temperature, an absolute zero? (Explain his reasoning.)
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The science of cold was about to suffer a serious setback. A rival theory of heat and cold emerged that was appealing, yet wrong. It was called the caloric theory, and its principle advocate was the great French chemist Antoine Lavoisier, 1700s France. In so many ways he was brilliant, and his careful experiments created much of modern day Chemistry. Lavoisier even developed the theory of conservation of matter. But on the topic of heat and cold, he was mistaken.
5. According to Lavoisier, what was “caloric”? Also, why do you think it is possible for a brilliant scientist to be so correct in so many other areas of science, yet completely incorrect in another area? (This isn’t answered within the program. I am looking for your thoughts.)
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One scientist was convinced that Lavoisier was wrong about caloric – and was determined to destroy the caloric theory. His name was Sir Benjamin Thompson, Count Rumford. (*) He was born in America, spied for the British during the Revolution, and after being forced into exile, became an influential government minister in Bavaria. Among his varied responsibilities was the artillery works, and it was here, in the 1790s, that he began to think about how he might be able to disprove the caloric theory.
6. How did he show that heat was not a fluid or material? In Count Rumford’s view, what was heat?
(*) Although his name was Ben Thompson, he is universally known as Count Rumford. What does that even mean? For his efforts in improving the life of people in the nation-state of Bavaria, he was made a Count of the Holy Roman Empire. Thompson took the name “Rumford” for Rumford, New Hampshire, the older name for the town of Concord.
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Michael Faraday, who later became famous for his work on electricity and magnetism, would take a critical early step in the long descent towards absolute zero. He was asked to investigate the properties of chlorine using crystals of chlorine hydrate, in 1823.
Faraday took the sealed tube and heated the end containing the chlorine hydrate in hot water. He put the other end in an ice bath. Soon he noticed yellow chlorine gas being given off. Because the gas is being produced, pressure’s building up inside this glass tube!
When Faraday did the experiment, a visitor, Dr. Paris, came by to see what he was up to. Paris pointed out some oily matter in the bottom of the tube. Faraday was curious, and decided to break open the tube…. The explosion sent shards of glass flying. With the sudden release of pressure, the oily liquid vanished.
7. What did Faraday learn about heat, cold, gas and pressure, from this?
Tesla and wireless power transmission
Nikola Tesla is one of the great scientists of the 20th century. He patented close to 300 inventions in electrical and mechanical engineering.
Many of Nikola Tesla’s inventions actually work. However, there are many urban legends surrounding his work, some of which have become the basis of conspiracy theories. Perhaps the most widely known is related to Tesla’s discovery that electrical power can be transmitted wirelessly, through the air, from one device to another.
Tesla demonstrated that some power from a Tesla coil could effectively be used to power light bulbs tens or hundreds of feet away. He then envisioned extending the power and range of these devices: he wanted to build a remote power station which could wirelessly power entire cities and towns. However, Tesla never actually worked through the math to prove that this would be efficient or possible, nor did he even demonstrate this level of usefulness.
There is a belief that Tesla “proved” that these towers could wirelessly power cities, and that either the government, or power companies, conspired to keep the details of how this works secret. Electrical engineers and physicists, however, hold that not only is there no conspiracy, but that basic laws of physics show that Tesla’s proposal was unworkable in practice. Below you will find details on why it does not work for large geographical areas.
The information below has been excerpted & adapted from https://en.wikipedia.org/wiki/Wireless_power (1/29/16)
Also see “The Cult of Nikola Tesla”
Inventor Nikola Tesla performed the first experiments in wireless power transmission at the turn of the 20th century. He has done more to popularize the idea than any other individual. From 1891 to 1904 he experimented with transmitting power by inductive and capacitive coupling, using spark-excited radio frequency resonant transformers, now called Tesla coils, which generated high AC voltages. With these he was able to transmit power for short distances without wires.
He found he could increase the distance by using a receiving LC circuit tuned to resonance with the transmitter’s LC circuit, using resonant inductive coupling.
At his Colorado Springs laboratory during 1899–1900, by using voltages of the order of 10 mega-volts generated by an enormous coil, he was able to light three incandescent lamps at a distance of about one hundred feet.
The resonant inductive coupling which Tesla pioneered is now a familiar technology used throughout electronics and is currently being widely applied to short-range wireless power systems.
The inductive and capacitive coupling used in Tesla’s experiments is a “near-field” effect, so it is not able to transmit power long distances. However, Tesla was obsessed with developing a wireless power distribution system that could transmit power directly into homes and factories, as proposed in his visionary 1900 article in Century magazine.
He claimed to be able to transmit power on a worldwide scale, using a method that involved conduction through the Earth and atmosphere. Tesla believed that the entire Earth could act as an electrical resonator, and that by driving current pulses into the Earth at its resonant frequency from a grounded Tesla coil working against an elevated capacitance, the potential of the Earth could be made to oscillate, and this alternating current could be received with a similar capacitive antenna tuned to resonance with it at any point on Earth.
Another of his ideas was to use balloons to suspend transmitting and receiving electrodes in the air above 30,000 feet (9,100 m) in altitude, where the pressure is lower. At this altitude, Tesla claimed, an ionized layer would allow electricity to be sent at high voltages (millions of volts) over long distances.
In 1901, Tesla began construction of a large high-voltage wireless power station, now called the Wardenclyffe Tower, at Shoreham, New York. Although he promoted it to investors as a transatlantic radiotelegraphy station, he also intended it to transmit electric power as a prototype transmitter for a “World Wireless System” that was to broadcast both information and power worldwide.
By 1904 his investors had pulled out, and the facility was never completed. Although Tesla claimed his ideas were proven, he had a history of failing to confirm his ideas by experiment, and there seems to be no evidence that he ever transmitted significant power beyond the short-range demonstrations above.
The only report of long-distance transmission by Tesla is a claim – not found in reliable sources – that in 1899 he wirelessly lit 200 light bulbs at a distance of 26 miles (42 km). There is no independent confirmation of this putative demonstration; Tesla did not mention it, and it does not appear in his meticulous laboratory notes. It originated in 1944 from Tesla’s first biographer, John J. O’Neill, who said he pieced it together from “fragmentary material… in a number of publications”.
In the 110 years since Tesla’s experiments, efforts using similar equipment have failed to achieve long distance power transmission, and the scientific consensus is his World Wireless system would not have worked. Tesla’s world power transmission scheme remains today what it was in Tesla’s time, a fascinating dream.
Tesla’s Big Mistake. Amasci.com – William Beaty
The real science of non-Hertzian waves, By Paul Nicholson
Wireless Energy Transfer, By Yue Ma
Advanced materials
Wireless Power Transmission: From Far-Field to Near-Field
How Relativity Connects Electric and Magnetic Fields
By Professor Michael Fowler, University of Virginia
A Magnetic Puzzle…
Suppose we have an infinitely long straight wire, having a charge density of electrons of –λ coulombs per meter, all moving at speed v to the right (recall typical speeds are centimeters per minute) and a neutralizing fixed background of positive charge, also of course λ coulombs per meter.
The current in the wire has magnitude I = λv (and actually is flowing to the left, since the moving electrons carry negative charge).
Suppose also that a positive charge q is outside the wire, a distance r from the axis, and this outside charge is moving at the same exact velocity as the electrons in the wire.
So how does this lead to the effect we know as magnetism? Read on . . .
ow Relativity Connects Electric and Magnetic Fields
AP Physics Learning Objectives
Essential Knowledge 1.D.3: Properties of space and time cannot always be treated as absolute.
a. Relativistic mass–energy equivalence is a reconceptualization of matter and energy as two manifestations of the same underlying entity, fully interconvertible, thereby rendering invalid the classically separate laws of conservation of mass and conservation of energy. Students will not be expected to know apparent mass or rest mass.
b. Measurements of length and time depend on speed. (Qualitative treatment only.) physics
Learning Objective 1.D.3.1: The student is able to articulate the reasons that classical mechanics must be replaced by special relativity to describe the experimental results and theoretical predictions that show that the properties of space and time are not absolute.
[Students will be expected to recognize situations in which non-relativistic classical physics breaks down and to explain how relativity addresses that breakdown, but students will not be expected to know in which of two reference frames a given series of events corresponds to a greater or lesser time interval, or a greater or lesser spatial distance; they will just need to know that observers in the two reference frames can “disagree” about some time and distance intervals.]
New MA science standards
The Massachusetts Board of Elementary and Secondary Education is adopting revised science standards. They are based on the Next Generation Science Standards, which itself is based on A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012), from the National Research Council of the National Academies.
External link: Adoption of 2016 Science and Technology/Engineering Standards
The Board of Early Education and Care (EEC) is scheduled to vote to adopt the Pre-Kindergarten STE standards on February 9, 2016. …Assuming the Board of Elementary and Secondary Education votes to adopt the 2016 STE Standards, the Department will then copyedit the full 2016 Massachusetts Science and Technology/Engineering Curriculum Framework. The Framework includes the standards and a variety of additional guidance and supporting materials….
We expect to publish and post the completed 2016 STE Curriculum Framework in early spring 2016. At that point, the Department will distribute copies … to schools… for their use in improving curriculum, instruction, and assessment in science and technology/engineering starting in the 2016-17 school year….high school STE MCAS assessments will be revised later on a timetable that provides fair notice to students and schools with respect to the science testing component of the state’s Competency Determination (high school graduation) requirement.
Science, engineering, and technology permeate nearly every facet of modern life and hold the key to solving many of humanity’s most pressing current and future challenges. The United States’ position in the global economy is declining, in part because U.S. workers lack fundamental knowledge in these fields. To address the critical issues of U.S. competitiveness and to better prepare the workforce, A Framework for K-12 Science Education proposes a new approach to K-12 science education that will capture students’ interest and provide them with the necessary foundational knowledge in the field.
A Framework for K-12 Science Education outlines a broad set of expectations for students in science and engineering in grades K-12. These expectations will inform the development of new standards for K-12 science education and, subsequently, revisions to curriculum, instruction, assessment, and professional development for educators.
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The high school Introductory Physics standards build from middle school and allow grade 9 or 10 students to explain additional and more complex phenomena central to the physical world. The standards expect students to apply a variety of science and engineering practices to three core ideas of physics:
Motion and Stability: Forces and Interactions support students’ understanding of ideas related to why some objects move in certain ways, why objects change their motion, and why some materials are attracted to each other while others are not. This core idea helps students answer the question, “How can one explain and predict interactions between objects and within systems of objects?” Students are able to demonstrate their understanding by applying scientific and engineering ideas related to Newton’s Second Law, total momentum, conservation, system analysis, and gravitational and electrostatic forces.
A focus on Energy develops students’ understanding of energy at both the macroscopic and atomic scale that can be accounted for as either motions of particles or energy stored in fields. This core idea helps students answer the question, “How is energy transferred and conserved?” Energy is understood as quantitative property of a system that depends on the motion and interactions of matter and radiation within that system, and the total change of energy in any system is always equal to the total energy transferred into or out of the system. Students apply their understandings to explain situations that involve conservation of energy, energy transfer, and tracing the relationship between energy and forces.
Waves and Their Applications in Technologies for Information Transfer support students’ understanding of the physical principles used in a wide variety of existing and emerging technologies. As such, this core idea helps students answer the question, “How are waves used to transfer energy and send and store information?”
Students are able to apply understanding of how wave properties and the interactions of electromagnetic radiation with matter can transfer information across long distances, store information, and investigate nature on many scales. Models of electromagnetic radiation as either a wave of changing electric and magnetic fields or as particles are developed and used. Students understand that combining waves of different frequencies can make a wide variety of patterns and thereby encode and transmit information. Students can demonstrate their understanding by explaining how the principles of wave behavior and wave interactions with matter are used in technological devices to transmit and capture information and energy.
PS1. Matter and Its Interactions
HS-PS1-8. Develop a model to illustrate the energy released or absorbed during the processes of fission, fusion, and radioactive decay.
Clarification Statements:
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Examples of models include simple qualitative models, such as pictures or diagrams.
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Types of radioactive decays include alpha, beta, and gamma.
State Assessment Boundary:
-
Quantitative calculations of energy released or absorbed are not expected in state assessment.
[Note: HS-PS1-1, HS-PS1-2, HS-PS1-3, HS-PS1-4, HS-PS1-5, HS-PS1-6, and HS-PS1-7 are found in Chemistry.]
PS2. Motion and Stability: Forces and Interactions
HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion is a mathematical model describing change in motion (the acceleration) of objects when acted on by a net force.
Clarification Statements:
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Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, and a moving object being pulled by a constant force.
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Forces can include contact forces, including friction, and forces acting at a distance, such as gravity and magnetic forces.
State Assessment Boundary:
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Variable forces are not expected in state assessment.
HS-PS2-2. Use mathematical representations to show that the total momentum of a system of interacting objects is conserved when there is no net force on the system.
Clarification Statement:
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Emphasis is on the qualitative meaning of the conservation of momentum and the quantitative understanding of the conservation of linear momentum in interactions involving elastic and inelastic collisions between two objects in one dimension.
HS-PS2-3. Apply scientific principles of motion and momentum to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.*
Clarification Statement:
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Both qualitative evaluations and algebraic manipulations may be used.
HS-PS2-4. Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to both qualitatively and quantitatively describe and predict the effects of gravitational and electrostatic forces between objects.
Clarification Statement:
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Emphasis is on the relative changes when distance, mass or charge, or both are changed; as well as the relative strength comparison between the two forces.
State Assessment Boundaries:
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State assessment will be limited to systems with two objects.
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Permittivity of free space is not expected in state assessment.
HS-PS2-5. Provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.
Clarification Statement:
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Examples of evidence can include movement of a magnetic compass when placed in the vicinity of a current-carrying wire, and a magnet passing through a coil that turns on the light of a Faraday flashlight.
State Assessment Boundary:
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Explanations of motors or generators are not expected in state assessment.
HS-PS2-9(MA). Evaluate simple series and parallel circuits to predict changes to voltage, current, or resistance when simple changes are made to a circuit.
Clarification Statements:
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Predictions of changes can be represented numerically, graphically, or algebraically using Ohm’s Law.
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Simple changes to a circuit may include adding a component, changing the resistance of a load, and adding a parallel path, in circuits with batteries and common loads.
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Simple circuits can be represented in schematic diagrams.
State Assessment Boundary:
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Use of measurement devices and predictions of changes in power are not expected in state assessment.
HS-PS2-10(MA). Use free-body force diagrams, algebraic expressions, and Newton’s laws of motion to predict changes to velocity and acceleration for an object moving in one dimension in various situations.
Clarification Statement:
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Predictions of changes in motion can be made numerically, graphically, and algebraically using basic equations for velocity, constant acceleration, and Newton’s first and second laws.
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Forces can include contact forces, including friction, and forces acting at a distance, such as gravity and magnetic forces.
[Note: HS-PS2-6, HS-PS2-7(MA), and HS-PS2-8(MA) are found in Chemistry.]
PS3. Energy
HS-PS3-1. Use algebraic expressions and the principle of energy conservation to calculate the change in energy of one component of a system when the change in energy of the other component(s) of the system, as well as the total energy of the system including any energy entering or leaving the system, is known. Identify any transformations from one form of energy to another, including thermal, kinetic, gravitational, magnetic, or electrical energy, in the system.
Clarification Statement:
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Systems should be limited to two or three components; and to thermal energy, kinetic energy, or the energies in gravitational, magnetic, or electric fields.
HS-PS3-2. Develop and use a model to illustrate that energy at the macroscopic scale can be accounted for as either motions of particles and objects or energy stored in fields.
Clarification Statements:
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Examples of phenomena at the macroscopic scale could include evaporation and condensation, the conversion of kinetic energy to thermal energy, the gravitational potential energy stored due to position of an object above the Earth, and the energy stored (electrical potential) of a charged object’s position within an electrical field.
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Examples of models could include diagrams, drawings, descriptions, and computer simulations.
HS-PS3-3. Design and evaluate a device that works within given constraints to convert one form of energy into another form of energy.*
Clarification Statements:
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Emphasis is on both qualitative and quantitative evaluations of devices.
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Examples of devices could include Rube Goldberg devices, wind turbines, solar cells, solar ovens, and generators.
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Examples of constraints could include use of renewable energy forms and efficiency.
State Assessment Boundary:
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Quantitative evaluations will be limited to total output for a given input in state assessment.
HS-PS3-4a. Provide evidence that when two objects of different temperature are in thermal contact within a closed system, the transfer of thermal energy from higher temperature objects to lower temperature objects results in thermal equilibrium, or a more uniform energy distribution among the objects and that temperature changes necessary to achieve thermal equilibrium depend on the specific heat values of the two substances.
Clarification Statement:
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Energy changes should be described both quantitatively in a single phase (Q = mc∆T) and conceptually in either a single phase or during a phase change.
HS-PS3-5. Develop and use a model of magnetic or electric fields to illustrate the forces and changes in energy between two magnetically or electrically charged objects changing relative position in a magnetic or electric field, respectively.
Clarification Statements:
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Emphasis is on the change in force and energy as objects move relative to each other.
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Examples of models could include drawings, diagrams, and texts, such as drawings of what happens when two charges of opposite polarity are near each other.
[Note: HS-PS3-4b is found in Chemistry.]
PS4. Waves and Their Applications in Technologies for Information Transfer
HS-PS4-1. Use mathematical representations to support a claim regarding relationships among the frequency, wavelength, and speed of waves traveling within various media. Recognize that electromagnetic waves can travel through empty space (without a medium) as compared to mechanical waves that require a medium.
Clarification Statements:
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Emphasis is on relationships when waves travel within a medium, and comparisons when a wave travels in different media.
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Examples of situations to consider could include electromagnetic radiation traveling in a vacuum and glass, sound waves traveling through air and water, and seismic waves traveling through the Earth.
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Relationships include v = λf, T = 1/f, and the qualitative comparison of the speed of a transverse (including electromagnetic) or longitudinal mechanical wave in a solid, liquid, gas, or vacuum.
State Assessment Boundary:
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Transitions between two media are not expected in state assessment.
HS-PS4-3. Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations involving resonance, interference, diffraction, refraction, or the photoelectric effect, one model is more useful than the other.
Clarification Statement:
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Emphasis is on qualitative reasoning and comparisons of the two models.
State Assessment Boundary:
-
Calculations of energy levels or resonant frequencies are not expected in state assessment.
HS-PS4-5. Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.*
Clarification Statements:
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Emphasis is on qualitative information and descriptions.
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Examples of technological devices could include solar cells capturing light and converting it to electricity; medical imaging; and communications technology.
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Examples of principles of wave behavior include resonance, photoelectric effect, and constructive and destructive interference.
State Assessment Boundary:
-
Band theory is not expected in state assessment.
[Note: HS-PS4-2 and HS-PS4-4 from NGSS are not included.]
Also see: A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)
The only human being in existence not in this photo
Michael Collins is the only human being in the history of the world, living or dead, who is not contained in the frame of this picture.
Michael Collins (born October 31, 1930), Major General, USAF, Ret., is an American former astronaut and test pilot. …His first spaceflight was on Gemini 10, in which he and Command Pilot John Young performed two rendezvous with different spacecraft and Collins undertook two EVAs. His second spaceflight was as the Command Module Pilot for Apollo 11 [July 16-24, 1969]. While he stayed in orbit around the Moon, Neil Armstrong and Buzz Aldrin left in the Lunar Module to make the first manned landing on its surface. Collins is one of only 24 people to have flown to the Moon. Michael Collins (Wikipedia)
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