Monday, December 23, 2013

ETHS, Chem-Phys Make News in Korean Science Education Article

A few weeks ago a reporter from South Korea visited the period 7-8 class of juniors, and observed a class very different from what typically happens in South Korean high school science classes - we were doing a lab, where students were using measurements to develop an empirical mathematical relationship for the period of a pendulum.  In addition, they were using and evaluating four different measuring techniques to get the timing data (stop watch, video, electronic force sensor, and a computer simulation to test the effect of gravity on the period).  In South Korea, a huge percentage of students complain they do not enjoy science, nor will go into science, as their schools must focus on strict testing and science is largely reduced to memorizing facts for those tests.  Check out the article here.

Also, check out more links related to our work with NU in STEM education, and our Korean connection.

A Computational Thinking Challenge - Developing a Programming Mentality a Graphical Way

Check out the site https://blockly-demo.appspot.com/static/apps/maze/index.html?lang=en.  There is a set of 10 challenges, where you have to set up a set of instructions (i.e. an algorithm), to accomplish the task.  You effectively are writing a program to solve the task, without actually using a programming language.  It is graphics based, instead, but it helps develop a programming mentality and begins teaching how a real program is structured and setup.  Enjoy!  And let me know if you figure out the last challenge in articular - it is tough, and I have not yet figured out the correct algorithm!  :-)

Thursday, December 12, 2013

Anthill Art (and complexity)

I've never seen anything quite like this.  Thanks to Aly for sending the link.  Check out the complexity and intricacy of an anthill.

Wednesday, December 11, 2013

How We Use Del (MV Calculus) in Physics

For students who are in multivariable (MV) calculus, one of the main topics you study has to do with the vector differential operator called del (the upside down triangle).  Using this operator we can define gradient, divergence, and curl.  Another useful operator for waves, E&M, quantum mechanics, and other physics topics, is the laplacian (del-squared).

In physics, gradients can be used to describe vectors that are directed from high values of a scalar quantity to low values.  An example is the force of gravity, which is directed to move objects from high potential energy to low potential energy. We have electric fields flow from high electric potential (voltage) towards low electric potential.  We see heat flow from high temperature towards low temperature, or air masses flow from high pressure towards low pressure.  These can all be described by gradients.

Divergence is used for vector fields that radiate from a point source.  This could be light, sound, radiation, gravitational fields, or electric fields, all radiating from point sources.

Curl is used for vector fields that circulate around some vector source.  A prime example is the circulating magnetic fields that are found around electric currents, or circulating electric fields around a changing magnetic field.

Check out the video to see a few examples, and hopefully you will see how these strange mathematical operators are applied to real, physical phenomena.

Learn General Relativity!!

Here is a 2 hour lesson on general relativity, taught at a relatively 'basic' level.  You need to know geometry, algebra, and some calculus.  I have watched a bit of this, and what I saw is quite good and understandable.  Give it a try if you are interested in more details about what Einstein's great theory says and predicts, and some of the mathematical concepts of general relativity.

Monday, December 9, 2013

How to Handle Dielectrics in Capacitors

Capacitors are circuit components that store charge and energy.  There are two surfaces, which take the shapes of either two plates, two concentric spheres, or two concentric cylinders.  One surface is positive, and the other equally charged negative.  An electric field in between the two surfaces provides the mechanism for storing energy.

By definition, capacitance is the ratio of the charge on one of the surfaces, Q, divided by the voltage difference between the surfaces, V.  We have C = Q/C.  If you want to see how we do this for spheres and cylinders, check out this video.

A dielectric is an insulating material that fills the gap between the charged surfaces, and essentially all capacitors in your electronic gadgets have dielectrics.  Dielectrics will partially polarize, produce a small opposing electric field due to the polarization, and weaken the net E-field of the capacitor.  This reduces the voltage difference, which finally increases the capacitance.  C_new = KC_o.  K is a dielectric constant > 1.

Check out the video, which also shows how to calculate the new capacitance when the gaps are partially filled with dielectrics, at least for parallel plate capacitors.

Sunday, December 8, 2013

How to do Multi-Loop Resistor Circuits

In E&M, one of the circuits we try to understand is a multi-loop resistor circuit.  This is a circuit that has multiple batteries arranged in a way that takes away our ability to find the total resistance in the circuit.  Basically, the multiple batteries ruin pure parallel combinations of resistors in our circuit.  We cannot find the total resistance, and therefore cannot find a total current for the circuit.  We need a new method since the traditional, usual method we learn to do does not work.

The technique of this video involves using Ohm's law and Kirchhoff's series rule (i.e. voltage of the batteries = sum of the voltage losses of the components of the loop) to set up loop equations, and then solve the loop equations for the loop currents.  The math is algebra, specifically solving a system of equations for multiple unknown currents.  Check it out, and I hope the example helps.

Project Excite Overview

As students have heard about in class, we are beginning work with our 14th cohort of Project Excite 3rd grade students.  But what is Project Excite?  What are these young students doing when they come over to ETHS ten times for science and math related activities?  Does this effort pay off?

One of the primary goals for Project Excite is to prepare minority students for honors and AP level science and math classes by the time they are in the high school.  The model for doing this revolves around the notion that we must start young.  The academic achievement gap begins forming very early, and many years prior to high school.  We start with the 3rd grade, where there is already a significant academic achievement gap, at least as represented by a variety of testing measures and teacher experience.

By working consistently with about two dozen students per cohort, the achievement gap is eliminated by the 7th grade on average, again as measured by some tests (ISAT and EXPLORE).  On paper, these students tend to be as strong and as prepared for high school as white students.  One issue that we may be seeing (this is a hypothesis) is related to stereotype threat, where on paper a group should be able to perform as well as other groups, but in reality they underperform.  This can happen in many contexts when there is a social stereotype or expectation that a group is supposed to underperform.  But if one can take away that stereotype threat, then the same group performs at the same level as the 'dominant' group.

Whatever the reason, we are now working on figuring out what supports are needed at the high school level to ensure the Excite students do well in those honors and AP classes, and get into top-tier colleges so they have multiple options available for majors and careers.

Saturday, December 7, 2013

Rotational Motion Introduction

Honestly, for many students rotational motion is the least familiar, and therefore challenging, topic in mechanics.  To help make our studies of rotations as painless and as familiar as possible, we will compare basic quantities needed for rotations to old favorites from linear motion.  Basically, just about everything we did in linear motion will have the same mathematical relationship in rotations.  For example, constant acceleration, Newton's 2nd law, and kinetic energy will all have the same general concept and form in rotations, just with new rotational quantities.

It is these basic rotations quantities that are introduced in this video. They include angular displacement, angular velocity, angular acceleration, torque, angular momentum, and rotational KE.

Friday, November 22, 2013

Simple Harmonic Motion

For simple harmonic motion, which is periodic motion where there is a restoring force proportional to the displacement (like a spring, F = -kx), there are several videos.  These are for the basic derivation, small angle approximations, and how to solve initial conditions problems.  A fourth video is an application to a simple 1-D quantum mechanics problem, which shows where quantum numbers come from!  Have fun!

E&M - Circuit Analysis

In 4 Chem-Phys, we are looking at circuit analysis for resistor circuits.  We have our rules: Ohm's law, V = IR; Series and Parallel resistances (add in series, add reciprocals in parallel and flip over); and Kirchhoff's 2 rules (in series voltages add to that of the battery, in parallel the currents add to the total).  A video for applying all this is here.

Thursday, November 21, 2013

Clean Tech Competition

There is a contest sponsored by the Center for Science Teaching and Learning, called the Clean Tech Competition. This one seems really interesting, where a team can identify a pollution problem in their community, or in any location in the world, and develop a clean energy solution for the problem.  If you are a finalist team, they will give a stipend to actually build the device, and you present your work.  There is a \$15,000 prize.  Check out the site here.  Ms. Fitzpatrick will be the sponsor of a team if there is interest!!

Let Doc V know if you are interested.

Sunday, November 3, 2013

Open-Ended Problem/Contest Resources

Just wanted to re-post the link to the article with info and links to helpful resources regarding the technical writing involved with presenting solutions to open-ended problems, as classes are working on project papers and teams are working on the COMAP contest.

Sunday, October 27, 2013

The Bermuda Triangle of Triangle Problems

Here is a good puzzler: How many triangles can you get from this picture?  Something like 93% get it wrong! Have fun...

Wednesday, October 23, 2013

Gravitational energy the Right Way

Check out this video in class.  Take notes on it, and you will need it for the exercise that follows for a rocket launch to the moon.

Tuesday, October 15, 2013

Example of Excel Solver

Ms. Fitzpatrick has led us through an example of using Excel Solver to do optimization problems, and a set of instructions for this can be found here.  Note that I have a folder with a number of helpful resources for our open-ended project (the bus problem), as well as contests like COMAP and Moody's, in Shared Documents on my school website.

Here is another example via video on how to use Solver, in case it is helpful.

Monday, October 7, 2013

Nobel Prizes 2013

The Nobel Prizes for 2013 are being announced this week.  First up, two Americans and a German share the prize for medicine and physiology, for their work in understanding the transport system in cells.  Check out the press release from the Nobel committee.

The Nobel for physics is not much of a surprise, with Peter Higgs (UK) and Francois Englert (Belgium) winning for their work on symmetry breaking and the Higgs field/boson that was confirmed at CERN over the past year. Check out the press release from the Nobel committee.  This one is especially cool for me since many former colleagues and friends from Fermilab, and two former students, are on the experiments that discovered the Higgs boson!!

The Nobel for chemistry was given to Martin Karplus (Harvard), Michael Levitt (Stanford), and Arieh Warshel (UCLA) for their work in developing computer simulations of chemical reactions.  These powerful simulations allow scientists to not just see what the end products are, but also predict and understand at timy time steps what actually happens during chemical reactions.  This work includes both Newton's laws as well as quantum mechanics.  Check out the press release.

The Nobel Peace Prize for 2013 was given to the Organization for the Prohibition of Chemical Weapons. Most recently, this group is going to play a key role in Syria, as the U.S. is leading he charge to eliminate chemical weapons from their weapons stockpiles. See the press release from the Nobel committee.

Monday, September 30, 2013

PhET Simulation for the Pendulum Lab

We are unable to vary the strength of gravity in the lab, so the way we can do this is to use a computer simulation.  Check out the PhET Physics Simulations, and in particular the Pendulum simulation. When running the simulation, focus on the gravity portion, where you can vary it using earth, moon, Jupiter, and no gravity.  Use the measuring tools to measure the period for each gravity setting, and you will use these data points to plot period (y-axis) vs. g (x-axis) in Excel, to get a best fit function.  Click on the image below to launch the simulation from here.

Some useful data: Earth g = 9.8 m/s^2; Jupiter g = 24.8 m/s^2; Moon g = 1.6 m/s^2.

Thursday, September 19, 2013

Cutting-edge Nanoscale Research of Friction

Scientists have studied friction for centuries, and yet there is still so much we do not understand about it because the origin of friction is at the molecular level.  Check out this article for a summary of recent research done at the nanoscale, as scientists are learning about what happens with individual atoms involved with friction forces.

How Could I not Put This On?! Learn String Theory via Bohemian Rhapsody!

This is simply an amazing song and video - I have to think you will enjoy it!  Learn string theory from a Master's student, who puts it down via Queen's Bohemian Rhapsody.  Enjoy!

Wednesday, September 11, 2013

Checking Out Electric Charge and E-Fields

As we begin Electricity and Magnetism, we want to investigate properties of electric charges and the electric fields they create at all points in space around the charge.  Before we formally spell out the properties of charge and the standard interpretations of those properties, it is more fun and educational for you to 'discover' the properties on your own if at all possible.  We will try a PhET simulation for you to use, and you can perform computer experiments to try and figure out some features of charges and fields based on your observations.

When using the 'Electric Field of Dreams' simulation, you can add electric charges with the Add button, and with properties play with adding both negative and positive charges.  By clicking on the Electric Field option at the top of the simulation window, you can set the E-field discreteness, which adds more field arrows to help you easily see what the fields look like from each charge.  Try to observe so you can answer the following questions:
- In which direction do the electric field vectors point for a positive charge? For a negative charge?
- What direction does an External electric field push a negative charge?  A positive charge?
- What determines how strong the electric force is between two charged particles?

Record your observations and answers to the above questions in your lab book.  There is also an ActivPhysics simulation you should open and run.  It is about the electric fields from point charges (number 11.4, Electric Field: Point Charges).  Work through the lesson, using the simulations to make observations and to answer questions presented in the lesson.  Also take advantage of the Advisor option in ActivPhysics, so you can compare your thoughts with the correct responses. This will provide a nice 'second opinion' to the PhET simulation. Again, focus on observations of E-field and force vectors relative to positive and negative charges.  You want to try to convince yourself of how this all works based on your observations and not so much on Doc V in class!  :-)

Thursday, September 5, 2013

Open-Ended Problems Resources

We have a team challenge, involving the development of an environmentally friendly bus fleet for a school district. This is a real-world, open-ended problem with different approaches that can be taken, and no single 'right' answer!  Complex problems hound us in all fields in real life, so being able to attack such problems and develop reasonable solutions is a skill set that is necessary in the 21st century. You are going to have to collaborate, do research to find reliable resources of large data sets, use technology to assist the process, communicate your work, use more advanced thinking and problem solving skills (such as developing a mathematical model), make predictions that can be tested against a real world sample, develop creative solutions, and so on!

To assist you, here are various resources that will hopefully be helpful for you and your team:

Check out other open-ended, complex problems from the COMAP High School Mathematical Modeling Contest (HiMCM) and the Moody's Mega Math Challenge. The home pages are: HiMCM and Moody's.

Problems from past contests are: HiMCM and Moody's.

Exemplar papers from Moody's.  This includes an ETHS team paper that took 5th place nationally!!!  See what a good paper looks like.  See how teams took a problem and broke it down into simpler pieces, and what assumptions they made.  See how a mathematical model was developed, and what math techniques went into the model's development.  See how they explained their work.  See how they used the model to make predictions that could be tested against real data and other information. See how they determined and explained the weaknesses of the model.  Might as well learn from some others who did a good job with this process!

Judge's perspectives from Moody's can be found on this page, and for COMAP on this page (pages 17-35).  These are especially useful because they point out what makes for an average solution paper compared to an outstanding solution paper!  Are you doing these things for your solution paper?  If not, why not?  How can you re-adjust and make the solution better?  If you had more time, what would you focus on to try and improve your solution proposal?

Teams might consider drawing out a flow chart early on in the process that outlines key components and assumptions you want to make.  Get a visual picture of what this all looks like, and think about what is connected to what.  Do you expect direct or inverse relationships?  Linear or non-linear?  What factor or parameter, when changed, will have an effect on other parts of the model/solution?

We hope these all help you in this process.  Good luck, and have fun with it!

Effective Effort and Growth Mindset

Here is a video we will discuss, and I hope you will think about at least a little.  It addresses some thoughts and ideas, largely from the field of psychology and the work of Carol Dweck, called effective effort and mindset.  Dweck proposes the notion that there are two main mindsets (in her book entitled Mindset) that are really important in education: fixed versus growth mindsets.

Over the past decade or two, scientists have learned much about the brain and how we learn.  The brain is malleable, meaning it can change throughout life.  Even with age, the brain can still grow, change, and form new synapses.  One can get smarter.  Intelligence is NOT fixed at birth, and those who buy into this incorrect notion and feel they are restricted naturally from getting smarter or doing better in school are in a fixed mindset.  Those who understand they really can improve with effort, and that their brains can grow and their intelligence is not fixed are in the growth mindset.  Dweck has seen in her studies significant differences between the success of fixed and growth mindset students (of all ages, gender, races and ethnicities, etc.).

Think of a student in a fixed mindset.  If intelligence is fixed, and your potential and abilities are therefore limited in learning, then why would one want to expend extra effort and energy into trying to learn something a second or more times?  Why try if it is pointless?  Some students in this mindset also view extra effort as a sign of low intelligence, because you either have it or you don't, and it is dumb to try if you don't have the intelligence.

A student in a growth mindset takes the approach that additional effort is wonderful!  Working harder and taking on continuous intellectual challenges is cool!  The reason is no different than in something like basketball - if you want to get better at shooting free throws, what do you do?  You try more free throws.  You work on your strength so it is easier to shoot.  You train your muscles to do the task.  A growth mindset identifies how the brain really works - it is like a muscle, and you can train it, by mental exercise, to do the task you want!  That is really neat!!

Check this video out, and think about it.  More importantly, think about your own approach.  Check out some of the science behind the claim the brain can grow, that one can become smarter by training the brain.

Tuesday, September 3, 2013

SAT II Time!!

For those seniors who are planning on taking the SAT II Physics Subject Test, we will begin some lunch time reviews soon.  The lunch reviews will focus on some optics, magnetism and electromagnetism.  We will do this a few weeks before you take the October test, so you will also have a couple weeks to practice and ask questions.  We will discuss this in class when you come into physics.

However, in the mean time, there is a really nice site for the SAT II Physics on SparkNotes.  It has explanations/notes on each topic, practice questions, and solutions for all questions, as well as strategy and what to expect on the SAT II.  As with other tests, there will be a curve, with a top score of 800 possible.  More to come on this, but definitely start checking out the web site so you can be reviewing.

Tuesday, August 27, 2013

How to do Vector Multiplication: Dot and Cross Products

There are times when we will have to multiply two vectors together to define some third quantity.  The strange thing is, there are two ways we can multiply vectors - one where we get a scalar for an answer, and a second where we get a new vector for an answer.  These are called dot (or scalar) products and cross (or vector) products, respectively.

Dot products have two ways of being calculated, and choose the method that makes it easier based on the information given in the problem.  Cross products are a bit more involved and require a 3x3 determinant to figure out the x, y, and z components of the new vector.

Geometrically, dot products multiply the two parallel components of the two vectors.  The formula, if we know the magnitudes of the two vectors, is A dot B = ABcos(theta).  And cross products multiply the two perpendicular components of the two vectors, or A x B = ABsin(theta).  In these definitions, theta is the angle between vectors A and B.

Sunday, August 18, 2013

Electron Micrographs of MANY Things

This is a page of beautiful photos (over 1100) from electron microscopes.  It shows some fascinating structures, and also the beauty and complexities of Nature. Check it out at:
http://www.flickr.com/photos/fei_company/

Sunday, August 11, 2013

Pretty Cool Animation of how a Digital Camera Works

This is a short and sweet animation of a Nokia digital camera.  See if you can identify the various steps in the process.

Wednesday, July 31, 2013

How to Use Tracker Video Analysis software

Every do often, we may be doing data analysis of events recorded by video.  This might be a ball thrown through the air, a video game, a cool YouTube video you find, or anything that has motion involved.  The goal is to get your data from the video.  We will have three main ways of doing this.

One way is a scaling exercise.  Quite literally, you can measure the sizes and distances on the computer monitor.  If you know the actual size of on object in the video (perhaps a person or meterstick), you can scale lengths of any other object in the video to get its size, or to measure the distance the object moves.  The other quantity we need is time.  This will require either timing the event on the video, which could include just reading the time stamp of the video or timing with a stopwatch if the video is running in real time.

The other two methods are very similar, and use software.  Logger Pro, which is the software we use to run our Vernier sensors, and Tracker, a free online program, can have any video on your hard drive imported for analysis.  It is really cool stuff, and below is a video that explains how to use Tracker to get data from a video where a ball is tossed in the air.  Watch and learn, and then you will have chances to do this with any video we use during the year (or better yet, on your own when you are curious about something you capture on video).

Keep in mind, you can upload video from a camcorder or your cell phone onto your computer.  What about if you want to analyze an existing YouTube video, or if you want to analyze an online video game?  You will need to make a screencast video and save it on your computer, and then import that video file (recommend MP4 video) into Tracker or Logger Pro.  The easiest way to make a screencast video is Screencast-o-matic.

Friday, July 12, 2013

Former Chem-Phys Student Featured in Wired, for Skybox Start-up

Dan Berkenstock, a former ETHS student who came through Chem-Phys, is now a VP at Skybox, a start-up technology company in Silicon Valley.  Skybox is getting good press in Wired magazine, which describes the mission of Skybox here.  Skybox is building a satellite network that will be able to take high resolution photos all around the Earth, and use the vast amount of data in those photos to companies, governments, and so on.  With only about a dozen satellites currently able to do this, Skybox is going to, perhaps, corner this market.  There could be enormous financial rewards waiting if successful, so time will tell.  But keep in mind Dan used to sit in your seats, so this shows one path for your young, creative minds!

Saturday, June 29, 2013

A really cool demonstration of momentum and energy.  Try to understand this one!  Where can we get long bead chains like this?!?!?!  We must try this one in class.

Thursday, June 6, 2013

TED: Freeman Hrabowski and his 4 Pillars of College Success

A talk from the President of University of Maryland, Baltimore.  He marched with Dr. Martin Luther King as a boy, and now works on getting minorities, the poor, and other underrepresented groups into science and math.

Video for an Explosive Use of Capacitors and Conservation of Momentum, Watermellon style!

Courtesy of Louis S.:

The video I chose actually represents two aspects of physics in this class.  The set-up of the watermelon explosion is simply a large bank of capacitors wired together in series with an extremely high voltage. When one of the capacitors is discharged, there is an enormous current that runs through the watermelon, causing it to explode. This shows the relationship between capacitance, voltage, and current.  The other portion of this class can be seen with the high speed camera showing the watermelon explode.  When the watermelon is initially at rest, its momentum is zero.  Then, once it explodes, all of the little pieces of watermelon-shrapnel must fly off such that the components of their motion must equal zero.

Saturday, June 1, 2013

Congratulations to the Class of 2013!! You will be missed

Each year this is a bittersweet time for me.  I hate to see the senior class leave, but at the same time I am tremendously happy for and proud of the students.  You are about to enter a new phase of life, and also one of the great times in life.  You are all prepared for college on the academic side, and you will quickly learn and adapt to independence on the personal and social sides.  Enjoy the experience!

Here's to the Class of 2013!  A job very well done!!
- Doc V

Friday, May 17, 2013

Congrats on Surviving AP Season!!

AP exams are done today, so Congratulations!!!!!

Friday, April 26, 2013

Samsung Short Essay Contest on How Technology Helps Us Learn

Samsung is sponsoring a short essay contest for high school students.  You can write and submit a 300-word essay: An essay up to 300 words on what you think about technology advancements and how it will change the way we learn in the future. Is it for the better?

This could be fun.  This is also only about a single page essay on any technology you wish to address.  Give it a try.  Five scholarships of \$1000 will be given to those papers judged as being the best.  Just let me know if you have an interest, and the link above allows you to sign up for the contest.

Tuesday, April 16, 2013

Possible Hints of Dark Matter

Check out current results from two experiments, that show first hints of evidence for dark matter.  This is a proposed explanation for the observed motions and structures of galaxies, which cannot be explained by the amount of observable matter astronomers measure.  It will be an exciting story to follow over the coming months and years, as more data is collected and analyzed and scrutinized by physicists.

Possible Discrepancy in the Size of a Proton - IF Real, New Physics???

New measurements of the size of a proton, using a new method of muon interactions with protons rather than electron interactions for protons, reveals a ~4% discrepancy in the proton radius between the two methods.  Physicists are trying to figure out if this is due to some mistake being made with the muon experiment, or possibly some misunderstanding of systematic uncertainties in the experiment, or other 'boring' explanations for the difference.  The story can be found here.

However, if this result and difference hold after all the investigations are completed and are statistically significant, then this could be an indication of new physics beyond the current Standard Model theory, which is the foundational theory in particle physics for the past five decades.  Time will tell as the current experiments, as well as new experiments being designed and run to check these results, are completed over the next 5-10 years.

This is a wonderful example of how science works.  Experimental results are published in peer-reviewed journals, and are scrutinized by the scientific community.  When a discrepancy comes up with well established and well tested ideas over long periods of time, one needs to seriously and open-mindedly look at all possible explanations for the discrepancy. Results must be reproducible by independent groups.  Possible new explanations must be considered and tested and debated.  It is a slow process, but the goal is to uncover the truths in Nature, if at all possible, based on physical evidence.  This makes for the excitement that scientists encounter in their research programs!

Saturday, March 30, 2013

EM Induction Links We Are Using

We are first keeping a focus on examples of Faraday's law where induced emf = -B dA/dt.  This is when the wire loop or circuit is moving into or out of a region where there is a magnetic field.

1) The good news is that the math is always the same - the result is induced emf = -Blv.

2) Also, because the free, delocalized electrons of a moving conductor are actually moving, they feel a magnetic force F = qv x B...this is the force that starts the current in the wire loop!

3) Then, this induced current is in the external Bfield, and feels a force F = Il x B.  This magnetic force on the wire loop will be opposite the velocity, acting like a magnetic brake.

Check out these videos:
http://docvphysics.blogspot.com/2012/04/moving-conducting-rod-through-b-field.html
http://docvphysics.blogspot.com/2012/03/how-to-find-terminal-velocity-of.html
http://docvphysics.blogspot.com/2012/04/rotating-conducting-rod-in-b-field.html

Some good simulations that show applications of EM induction.  Play with these, change parameters, and observe what the effects are of things like rate of change of flux, how the flux changes, the number of coils, DC versus AC currents, and the area of the coils.
http://phet.colorado.edu/en/simulation/generator  Click on Run Now, and see the five different simulations that can be run, including generators and transformers and pick-up coils.  Also keep Lenz's law in mind to see if Nature is trying to stop the magnetic flux from changing.

Also, this one is on Faraday's law:
http://phet.colorado.edu/en/simulation/faradays-law Click on Run Now, and move the magnet like in our labs  to create an AC current.  Pay attention to Lenz's law, and see if it makes sense with what you observe in the simulation.

Saturday, March 16, 2013

The Higgs is Officially Discovered!

Watch and learn the history of physics from the ancient Greeks up to the newly discovered Higgs boson, in just 30 minutes!  One of the speakers in the video is Melissa Franklin, who I knew at Fermilab.  She is a physics professor at Harvard.

Saturday, March 2, 2013

Some thoughts about da Vinci and Education

Just some thoughts I have about one of the great minds in human history, Leonardo da Vinci, and education, including a progressive model of John Dewey.  Check it out here if interested.

Wednesday, February 20, 2013

Scientific vs Artistic Genius - Same or Different?

Courtesy Noah E.:

This is just an interesting clip from interviews of some scientists trying to address the differences and similarities between being a creative (artistic) genius and a scientific genius. This is interesting because probable the most fascinating parts of science are more abstract, so we definitely need those creative thinkers. Another thing they touch on is how "geniuses" come up with many of their ideas.

Tuesday, February 19, 2013

Quantum Levitation

Courtesy Caleb C.:

Some Quantum!

Courtesy of Joe Z.:

This video gives some history behind the origins of quantum mechanics. I enjoyed it because it was interesting, visually creative, and was able to explain a complex concept in relatable way.

How High Can Humans Build?

Courtesy of Nathan S.:

I've pasted the link to a vsauce video: "How High Can We Build". This topic was interesting to me for its relevancy, as Earth's ever expanding population will eventually force us to somehow use space more efficiently, building into the sky would certainly help in this endeavor. The topic also interested me as the reason we have a height limit is due to gravity which we study on a regular basis.

Monday, February 18, 2013

Tesla Coil Concert

Courtesy of Alex N.:

This video has a lot to do with E&M, and shows how well a Tesla coil can be used for other things than science experiments. Its a tad goofy, and the music it plays doesn't exactly sound right, however its cool to see and hear at the parts that are similar. It has to use an immense amount of power to just play that one song, however it seems to be well worth it. Plus its a good song.

Sunday, February 17, 2013

Use of Mosquitoes to Fight Disease?!

Courtesy of Taed C.:

Re-engineering mosquitoes to fight diseases!

Inner Life of a Cell

Courtesy Zach F.:

This is a video of the processes that occur within a cell that allow for some of the basic functions of cell groups within our body, such as sending and receiving signals through proteins and the specific method through which these proteins and bodily functions achieve their goals. Several individual organelles are shown too and their functions are conveyed through this three-dimensional animation. It demonstrates the immense volume of processes and it puts into perspective the complexity of our bodies and how much we understand about their functioning.

The Higgs

Courtesy of Rebecca P.:

Related to the Higgs Boson.

http://phys.org/news/2013-02-higgs-boson-scientists-quantum.html

Deflecting Asteroids

Very relevant to recent events, courtesy of Emma S.:

This is an article about a possible way of destroying asteroids that is being developed. Basically it talks about something called the Yarkovsky effect (how thermal radiation can create a force that can change the trajectory of an asteroid), and how painting asteroids (or, rather, spraying them with powder) can alter their course slightly.

Article at: http://www.wired.com/wiredscience/2013/02/painting-asteroids/

Long-term Data Storage Possibility

Courtesy Manny D.:

It's about information storage using thin slivers of quartz glass. These slivers have 4 layers where dots an imprinted on the quartz to store information in binary. These can work better than CD players or hard drives since they don't melt at temperatures up to 1,000 Fahrenheit. Also, even if they erode, they have 4 layers so the information is safe. This is important since we can save information without worrying about it being destroyed easily, like in CD's that can't be repaired.

How a Straw Works

Courtesy Lloyd S.:

This video shows, oddly enough, the physics of sucking a liquid from a straw. The straw deals with the pressure of the air and the pressure from within on your mouth. In this video they try to suck liquids from increasingly high heights. They calculate that the Max height possible is 10.3 m, yet when they attempt this height, they fail. I never realized how scientific drinking a coke could be.

Metronomes Becoming Synched!

This video portrays thirty two different metronomes, set at different initial positions, ultimately synchronizing into the same period. This occurs presumably as the table upon which the metronomes are situated is able to move with the metronomes and cause them to interact. It takes a surprisingly short amount of time for the metronomes to synchronize. Enjoy!

The Physics of Bubbles

Courtesy Henry M. and Nina D. - they both thought this is WAY COOL!:

I think it is really interesting how something that seems so simple as a bubble popping is actually more complicated than you may think. It was also really awesome at 2:38 when he shows how you can put your hand inside a bubble. While this video doesn't exactly discuss any concepts we are studying right now, it reminds me of how we take a seemingly simple process in class, and find that there are many different concepts of physics in play.

Strongest Magnet!

Courtesy Ben G.:

Check out the world's strongest magnet!

Deja Vu All Over Again...

Courtesy Olivia G.:

This video is about the study of Deja Vu and other similar phenomenon like Hypnogogic Jerk, Presque Vu, and Jamais Vu. The man in the video explains how these things happen and how they are related to our brains. This topic is worth sharing because the phenomenon discussed are things that happen to me often, and many other people as well. Since people know so little about the brain, it is important to keep studying it.

Courtesy Ben M.:

Here is a really cool article on an experiment done recently on some
lab rats at Duke University. They found they were able to literally
give these rats a sixth sense, the ability to sense infrared light
which is normally not visible. By implanting microelectrodes in their
brains, scientists were able to force a reaction to infrared light,
which after a time the rat began to understand. The significance of
this is that now in theory a human with a damaged visual cortex would
be able to regain sight through a device implanted in another part of
the brain.

Courtesy Nathan H.:

Talking about how black-holes form, what it would look like to go into one, dumb-holes, universe stuff.

We Are ALL Related!

Courtesy Tovah K.:

This video is really interesting because it is all shockingly true (I assume) and is pretty relevant to everyone on Earth.

How Qatar has Water, with No Natural Water Source

Courtesy of Quinn F.:

This talks about how to provide water to a nation(Qatar) which has no natural water source. It discusses Qatar's history, and why a lack of water has affected Qatar, and more importantly, solutions to the problem. While this method may not be useful to all of the world's population, it represents a large step in solving the global resource problem by turning a non-renewable resource into a renewable resource.

Couresy of Duncan L.:

In this TED talk, Erik Schlangen discusses a new form of porous asphalt formed from simple materials  that when cracked can be fixed using induction heating. This new material can potentially cut down on infrastructure costs, as paved roads made from traditional asphalt are much more expensive and difficult to repair. Schlangen hopes that his asphalt material will be put into widespread use in order to double the service life of roads.

A Person-made Black Hole at CERN?! A Rap!

Courtesy of Talia W.:

The Large Hadron Collider (LHC) at CERN has received a good deal of media attention due to the claim that it has the capacity to create microscopic black holes with the potential to destroy the earth (mostly before 2010, although a recent court case in Germany raised the supposed danger again). This video by Alpinekat, the (renowned) creator and performer of the "Large Hadron Rap," refutes the assertions that the earth could be drawn into an LHC-created black hole. She notes that if this were possible (which Stephen Hawking doesn't think it is), high-energy cosmic rays should have destroyed our planet long ago, and that if the LHC could create black holes, they would be too small to pull anything in and would quickly disintegrate. This video is significant in that it targets a major misconception; media attention for CERN and other scientific research is good – as long as it's the right kind.

Accelerating Ping Pong Balls

Courtesy of Tim R.:

Basically, this video utilizes the concept of pressure and vacuums to accelerate a ping pong ball to supersonic speeds, enough to send it straight through a paddle. Teh pinp pong ball is placed inside a vacuum tube, and pressurized air is shot extremely fast through it, pushing the ball at very high speeds, somewhere around Mach l.23, I believe. The actual event happens at around 5:48, with the time before it being explanation of the concepts. I thought it was pretty cool, so I hope I gave you everything you need to put it on the class blog.

A Water Repellant

Courtesy Ben B.:

Ultra-Ever-Dry is a super hydrophobic, and oleophobic, spray on coating. Anything it covers repels water completely. The uses for this product are many. It can be used to protect things from almost any type of liquid, which could reduce water damage in things like shoes, cars, floors, clothes, or any other product that needs water-proofing. Besides its practical uses, it also has a variety of fun/interesting possibilities. Imagine going swimming with a water proof body or pranking someone by spraying this on the inside of a cup. Probably one of the best things about Ultra-Ever-Dry is that it is a spray from a can, meaning it can be applied to almost anything. With this product, anything that might have a feasible need to be waterproofed can be waterproofed.

Physics Misconceptions

Courtesy of Violet L.:

This is video that compares the difference between the basics we have learned and what actually happens in physics. Examples include velocity and gravity.

Dark Energy in a Minute

Courtesy of Isabel A.:

his fascinating video by minutephysics goes into the basics of dark energy. It specifically unveils the complexity of the acceleration of the universe, a discovery that was awarded the Nobel Prize in Physics in 2011. The creators of this video are able to turn an extremely vast and unknown topic into something that anyone could understand. I thought that the idea of empty energy 'pushing' us away from distant galaxies was especially interesting.

6th Sense Technology

Courtesy of Dan L.:

This is a TED video on Pranav Mistry who talks about his "Sixth Sense" technology which helps link the physical and information worlds. The device is essentially a computer that displays information anywhere you are and allows you to interact with it without a keyboard. Besides the exciting implications of the technology, I was very impressed by how he documented his progression in creating it. It was fascinating to watch his curious tinkering turn into a jaw-dropping device.

Colonizing the Moon???

Courtesy of Troyer:

This video describes how we are planning to set up colonies on the moon. There are plans to use robots to build sturdy houses fit for space.

http://youtu.be/6MQCs2sVX5A

Friday, February 15, 2013

Strong Magnets

This comes courtesy Ben G.:

This video is about a lab in Florida that has the biggest magnet on the planet, so strong that it can levitate fruit!  It is explained in the video that the way that these electro-magnets are able to be made so strong is by the incredible density of its coils.  As well as the fact that a few of these coils are stacked within each other, amplifying the magnet.  I thought this was interesting because I had no idea that you could levitate non-metal objects with magnets.

Waves in Space

This comes courtesy of Luke S.:

This is an extremely cool video that demonstrates momentum and waves in space. It is almost like the physics land that we deal with so much in class. With an absence of a strong gravitational and friction force, most of the friction in these water droplet collisions is visibly conserved. It is also interesting to note the strength of the hydrogen bonds in keeping the water together.

Mandelbrot and Fractals

This comes courtesy of David D.:

The following is a TED talk by famous mathematician Benoit Mandelbrot  His work in explaining and giving patterns to the chaos of roughness is very interesting to me. Moreover, his understanding of fractals have deep practical benefits in various areas of science, as well as explaining the natural world:

This comes courtesy of Annik L.:

The brain is a huge contributing factor to the fascinating mystery that makes us human. It's interesting how one object can be both beneficial and malignant to us.  Scientists found that the same prions that trigger mad cow disease, and in humans the Creutzfeldt–Jakob Disease, are also involved in insulating nerves, maintaining the myelin sheath, and communicating between nerves.

Biomimetics in Engineering - Learn from Nature

This comes courtesy of Stephanie Y.:

This remains to be one of my favorite Ted Talks. It presents the concept of integrating solutions to world problems from nature in to present day building and engineering techniques. One example of this concept of biomickery was derived from the nubian beattle. Its shell is hydrophillic, meaning that it attracts water, and due to this property, the beattle is allowed to attract gaseous water in the air to its shell at night and from drinkable water. This technique can be applied to desert buildings in order to "cultivate" water from desert areas.

Flying bird robot!

This comes courtesy Danny K.:

This video was a TED talk that came out a bit over a year ago that shows how a research team was able to develop a robot that looks and acts like a bird. It flies by flapping its wings and is able to make relatively sharp turns. I feel like this video is so cool because it shows how we're getting close to being able to find out how birds can fly, glide, and turn so efficiently. If we can improve the technology, a new efficient form of air travel can be created, which I think is really cool.

Tuesday, February 12, 2013

Humans playing the role of host to many critters

This comes courtesy of Lewis H.:

This talks about the human Biome. It discusses how we are hosts to
millions of microbes that aren't the same as for every different
person. We know the bad microbes, pathogens, but we don't know about
the good ones. He is studying the effect of the good bacteria on the
human body. Watch for yourself to discover more.

Monday, February 11, 2013

Energy from Algae - Possible Future Energy Source

This comes courtesy of Aaron S.:

This is my contribution to the blog. In this Ted Talk, Jonathan Trent talks about his OMEGA (Offshore Membrane Enclosures for Growing Algae) project. The goal of this project is to farm micro-algae that would produce energy by feeding on the wastewater from cities. The process also utilizes the consumption of carbon dioxide and solar power. In today's world where there is a growing need for alternative energy, projects like Jonathan's are increasingly important.

Dreams!

This comes courtesy of Paul P:

The video discusses how to become a lucid dreamer and the science behind the properties of lucid dreams, a topic which has always interested me.

Regenerative Medicine

This comes courtesy of Clara L.:

Regenerative medicine has the capabilities to cure auto immune diseases. These diseases occur when the immune system of a person attacks healthy cells many time making an organ or function non functioning. As a type one diabetic which is an auto immune disease, regenerative medicine has the capabilities to cure me which is why I show such interest.

Sunday, February 10, 2013

Some Good Science Channels! Lots to check out!

This comes courtesy of Dalyan K.:

Here's a video that I think is relevant to the topic we studied in class and takes an interesting approach. There are a lot of good science videos on YouTube that you may or may not know about.

These are four channels that are my favorites in case you are interested.

Wing Suit Diving!

This comes courtesy Sam G.:

Wing suit diving encompasses the mechanical idea that, by increasing the body's surface area, you can slow down your rate of descent and increase your horizontal velocity.  These suits consists of three "webs": two covering the area between the right and left arms and the thigh and the third between the jumper's two legs.  Once the suits are fully opened, experienced wing suit divers can reach a glide ratio of almost 3 meters (meaning that for every meter fallen, three meters are traveled horizontally).  A typical skydiver's vertical terminal velocity is usually between 110-140 mph however experienced wing suit jumpers can bring their vertical velocity to less than 25 mph and their horizontal velocities above 150 mph.  In this video Jeb Corliss pilots his body in such a way that he is able to come down very close to a grassy field before flying into a large canyon.  Diver's can control their ratio of forward velocity to vertical velocity by changing the shape of their body at the torso, shoulders, and knees.  These different movements control the tension that is put on the suit from air friction and help to control the descent.

This comes courtesy of Olivia C.:

This is a video from Scientific American. It's a physicist and contributing editor to the magazine answering a series of insightful questions posted as comments by youtube users, which is cool because they're everyday people. All of the questions concern space or relativity.

Enjoy!

The Sound Around Us

This comes courtesy of Nick E.:

Here's the thing I think people would find cool - I think that we don't often thing about how we hear the sounds and noises all around us. And I just thought that it was really cool and that she does a really good job of describing this.

Friday, February 8, 2013

Why is the Night Sky Dark, and not Bright??

This comes courtesy of Josh L.:

This video is about why the night sky is dark. The sky is only blue during the day because sunlight scatters
off our Earth's atmosphere, so how about if we didn't have an atmosphere? We would think that because of all the stars in the galaxy, their light should brighten the sky, but this video explains what actually occurs.

I found this very interesting because it connected conceptual physics ideas that we have already learned about in the past (Universe Expanding, Doppler Effect) to explain a very intriguing question that I never really thought much about before this.

Hope you enjoy!

Fractal music!

This comes courtesy of Jack N.:

You may (or may not, if you are on the brink of sanity) enjoy the following video whose music, by renowned algorithmic composer RenÃ©-Louis Baron (recipient of the first patent in mathematical music composition), is constructed entirely with fractal pattern employment. For those of you not following, that means every single note was chosen as part of a larger, iterated mathematical pattern translated to music. The crux of fractal music is often what is referred to as the Cantor set-a recursively-defined pattern whose elements are represented by:

Asub(n)=Asub(n-1) \ U < iterated: k approaches infinity from k=0> [(1+3k)/3^n, (2+3k)/3^n]
or
C=∏Asub(n)

...obviously. I mean, Beethoven did it for his first Ecossaise. The essence of fractal music created with Cantor's pattern lies in its iterated, fractal sequences based on multiples of sixteen often in what are hierarchical, or architectonic patterns-musicologist jargon for chromatic fractal arrangement.
While the music may sound terrible, it's sadistically thrilling to think how much time one French guy wasted in composing it using Cantor's set and what sounds like the synthesizer from Super Mario 64.
Think while you listen.

Black Holes

This comes courtesy of Shai M:

This is a cool video about black holes.  Black holes are large stars that collapse under their own gravity into a very small volume of space, called a Schwartzschild radius.  This video has some nice graphics that show what a black hole would look like from outside, including the gravitational lensing effects a black hole would have on light coming from behind it.

Ferrofluid

This comes courtesy of Taylor S:

This is a video about ferrofluid. Ferrofluid is a liquid that becomes strongly magnetized when exposed to a magnetic fluid. Ferrofluid is composed of a ferromagnetic solute is dissolved in a solute. The spikey portions are where the electromagnetic field is the strongest. I love ferrofluid because of the really cool-looking and interesting shapes it makes when the electromagnetic field is turned on and off.

Sunday, January 20, 2013

Moodle is Still Down - Another Site to Access Some Old AP Problems and Solutions

The ETHS server housing Moodle has been down since Thursday, and is still not fixed.  We do not have access to AP exams and solutions.  Here is another site that has EM exams up to 2002, with solutions.  After 2002, there are only mechanics exams.

For 2002 to 2012, the College Board has the  free response problems and solution keys, as well.  Check here!

I hope this helps a bit.  Many thanks to Erin R. for finding it!!

Wednesday, January 16, 2013

National Climate Assessment Report

If interested, check out the National Climate Assessment report, which is still in draft form.  There are 30 chapters on numerous aspects of U.S. interests that may be affected by climate.  This is a report being reviewed by the National Academies of Science, and will eventually be passed along to the Federal Government for consideration when making policy.  Let's hope reasonable minds will allow for the science to be a major guide in this process, rather than personal, financial, or political motivations overrun facts and evidence.

Tuesday, January 8, 2013

"Hardest" Majors? Engineering and Physics Top of List

A study of college students and how much time they report studying and preparing for their classes shows that engineering and physics students need to spend the most time.  This suggests that these two majors are among the most, if not the most, challenging.  This ultimately is a subjective sort of topic which leads to good debates among students and graduates, but it is likely to be about right.  Speaking from my own experience, engineering and physics students spent more time in their studies when I was in school, with often long problem sets, technically challenging topics that simply require a large amount of time to mentally digest, for engineers spending what may seem like endless hours trying to get projects working, and for physicists spending many hours in labs and research.  This would also be true for just about any science major.

Most majors in college are going to be challenging and require hard work, but a student will know if it is the right major for them if the work is difficult and yet fun, because if it is something one truly enjoys and wants to do as a career, it will be quite rewarding as time goes on.

Sunday, January 6, 2013

Case Where BOTH Linear AND Angular Momenta are Conserved!

We are used to collisions where either linear momentum is conserved, such as two billiard balls colliding, or just angular momentum is conserved, such as when a kid jumps and lands on a merry-go-round on a playground.  We are not used to seeing cases where BOTH types of momentum are conserved.  But this can happen!

How??

When there are no net forces acting on a system, linear momentum is conserved for the system.
When there are no net torques acting on a system, angular momentum is conserved for the system.

This can happen for a rod lying on a sheet of ice or air table, where there is no friction and gravity does not affect the horizontal motion.  No part of the rod is nailed down, so the entire rod is free to move, and not just rotate.  If a particle comes flying in and sticks to the rod, then we would have both linear motion and rotational motion of the system!  And both momenta would be conserved.

A key thing to take away from this example is that there is a new center of mass of the system.  This is the key point in the problem since i) this is the point that will move along a straight line after the collision, and ii) it is the axis of rotation of the system after the collision!  Check out how to set this bugger up, and see if it makes sense.

How to do Conservation of Angular Momentum in Inelastic Collisions

This video goes through the setup for two examples of Inelastic collisions that involve rotations.  One is a sky diver landing on a spinning merry-go-round (disk) at some angle, and the sky diver 'sticks' to the platform.  If there is a component of the sky diver's motion that is perpendicular to the rotational motion of the disk, then the rotational motion will change.  Angular momentum is conserved for the system if there is no external torque acting on the system, which is the case here.  So we use the definition L = Iw for the disk since it is actually rotating, and L = mvrsin(angle between the line of motion and radius from axis of rotation).  Again, like torque, we are looking for the component of motion perpendicular to the radius line, since that is the component that can affect the rotation of the system.

The second example is a particle moving linearly running into and sticking to a stick that is nailed down at its center. After the collision, the system only spins, so we have both L = Iw and L = mvrsin(angle).  See if the setups make sense.