Search This Blog

Sunday, May 21, 2017

Video analysis and the mass of the moon

We will investigate physics through the use of video analysis. The reasons for doing this includes a primary one of using Logger Pro software, which the school has from the Vernier electronic sensors, to do a video analysis. I want you to realize you can take any YouTube video, or any video (or digital photo) you take with your phone, and analyze any type of motion in any event you capture! This is a powerful tool that we all have access to in this day and age, and allows us to do so many more analyses. And with high-speed video options that more phones are providing, such as 120 frames per second (fps), 240 fps, and even 480 fps, or digital cameras that now provide 1000 fps or more, we can use video analysis software to look at finer details of motion than we ever could before in a high school lab. Keep in mind that a normal video is around 30 fps.

Watch this video for getting an introduction to using Logger Pro for video analysis.

One thing I recommend is to download a free piece of software called Tracker on a home computer (cannot do this with the Chromebooks, unfortunately), so you have the chance to check out details if you ever get the urge. This is an introductory video for using Tracker.

All you need is a few seconds of video to get into an analysis. For today we have as a goal to figure out the mass of the moon, perhaps using the original video footage of the first men on the moon in 1969! All you need is a bit of projectile motion to figure out the acceleration due to gravity, and the fact that the radius of the moon is 1079 miles. Work with a partner, and keep in mind you need to Google some conversions and get the mass of the moon in kilograms based on data from the video.You can use any moon landing video you want, including the moon buggy, dropping a hammer and falcon feather, or any other that involves some gravitational action you can use to figure this out. Also come up with a percent error compared to an accepted value of the moon mass.

Note that to import a video clip into Logger Pro or Tracker, you need to have the video file. To get this from your phone, of course you would need to just upload the video to your computer and then import into the software. For a YouTube video, you can make a screencast video file of the YouTube video, and save it to your computer. A quick, easy way to do this is to use Screencast-o-matic. Just select the brief scene you need to do the analysis, and capture it with the screencast! Here's a how to video for making a Screencast-o-matic video, which I suggest saving to your desktop or to your student My Documents folder. You will be able to Insert this video file into Logger Pro.


Monday, May 15, 2017

Video on the human eye

One video on the details of our eyes is here, or click on the embedded video below. An alternative is here.

Saturday, April 29, 2017

Funding site for the Kranti School in India

We were so fortunate for many students to meet Robin Chaurasiya, who stopped by ETHS while in Chicago. Her work in Mumbai, India, at the Kranti School, has gained her international attention, including a Top 10 Finalist rating in the 2016 Global Teacher Prize! She works with girls who have either been in or whose mothers were in the sex trade.

What needs to be known is Robin's school is a NGO (Non-Government Organization), and every penny to run the school and pay for some of the girls to study abroad and go to college has to be raised - there is no tax money or fixed revenue for such a school. If there is any interest in making any donation, whether small or large, one can check it out at this site. Through this site, 100% of the donations go to Kranti!

Wednesday, April 26, 2017

EM Work

For review, let's go into the AP Multiple Choice folder on your chromebook, and try the 2015 test (if this link does not work, go to the AP Exams folder and then into the Mult Choice folder). Remember you need to be logged into your account to access these folders. You'll need to scroll down in that file to get to the questions, and the answer key is towards the end of the file.

It is up to you if you want to start by yourself and then work with others on anything you missed, or if you want to talk through things with one or two others. If individually, also keep a sense of pace by timing yourself for some number of questions.

*The important thing is to find things that you have forgotten or have had some trouble with in the past. Turn in your answer sheet and score. Whatever time you have left, you can work on the review set from the other day. Come with questions Thursday!  😊

Wednesday, April 19, 2017

Visitor on Tuesday, April 25: Robin Chaurasiya

Check out a brief bio of Robin Chaurasiya, who will be in town and visiting ETHS on Tuesday, April 25, in room H322. Come by during lunch periods to meet her and hear some thoughts about what she does in India with her students. There is also a good video showing what the girls do in terms of performance at the Kranti School.

Tuesday, April 11, 2017

PhET simulation for EM induction

We will be trying the generator and transformer simulations for class. Check it out! The link is

Monday, April 10, 2017

Inductor Circuits!

We are moving into the final topic of high school physics: Inductors!

Check out a few videos if you need to review or double-check anything:

- series RL circuit
- Parallel RL circuit 
- LC circuit 

- Maxwell's displacement current, about how capacitors work and the final piece to Maxwell's equations
- Maxwell's equations (Mechanical Universe episode; good graphics of EM waves)

Tuesday, April 4, 2017

EM Induction Links

For Tuesday:

Check out the case emf = B dA/dt, where the circuit moves and the area changes. This is an example of a magnetic brake, where the loop will start to slow down due to the weird induction phenomena.

Then, a special example of this type of induction, where the circuit falls through a magnetic field (in other words, when there is a constant force trying to accelerate the circuit/loop. This is going to end up looking a lot like air friction on a skydiver, with a terminal velocity!

By the way, check this one out if you want to see a strange case of finding the magnetic flux through a circuit due to the magnetism from a long, straight wire next to the circuit.

On Wednesday, which you have off, check out a preview of the other case, where emf = A dB/dt. This is going to involve a circulating electric field! Weird, but welcome to the world of electromagnetism. Here is a video specifically on the circulating E-field that is created when there is dB/dt.    :-)

Tuesday, March 14, 2017

Links for the week

I hope the rest of the week is great for everyone!

For periods 1-2, 8-9:

Check out and take notes on a video about the parallel-axis theorem. This is a nice way of getting moments of inertia in certain instances.
Also, let's try to figure out rolling without slipping, and finding things like the friction and accelerations associated with rolling objects.

Today, let's try two other cases. The first is rolling without slipping, but then going up a frictionless incline. Then, the dreaded rolling WITH slipping!

Can watch the video "Runaway Universe," on DVD. Check out the methods used to figure out what the universe is doing. Have a good weekend!

Check out an introduction to angular momentum. We will pick up with this Tuesday.

For Period 3:
Here is a bit of a break from electricity. Let's watch the video "Runaway Universe," on DVD. Check out the methods used to figure out what the universe is doing; write down some techniques you see in the video.

Back to electricity. Today let's get an introduction into some basics of an electric circuit. Check out a Khan video about a circuit and Ohm's law. Then, check out some basics of materials we find in a circuit, with resistivity and conductivity.

There's an interesting documentary on electricity - check it out and take notes on different applications of electricity, and the main concept behind the applications. Have a good weekend!

Saturday, March 11, 2017

A good description of what schools SHOULD look like, but don't

Anyone who knows me is aware of my stance on what schools generally are doing to prepare students for the world, compared to what schools SHOULD be doing...I have been preaching for years that we are NOT running schools the way we should that would best benefit the students, but do to politics, we continue to think in terms of accountability and standardized test scores, and the traditional schedule and curricula. One model for what a high school could look like is here, and another model for a grade 9-10 science course can be found here. I've had these lying around for some number of years, and am always looking for thoughts and feedback, and a chance to try them!

Ted Dintersmith does a really nice job in this talk as he addresses this issue. He is responsible for the film "Most Likely to Succeed," and as someone who made his money as an innovator, he has firsthand experience of the qualities, skills, and topics schools should be getting to the next generation.

Monday, February 27, 2017

Links Useful to Tuesday, Feb. 28

Happy Tuesday, one and all!

For Periods 1-2, 5-6, 8-9:

It is time to start digesting Biot-Savart for magnetic fields, due to real wires. Unfortunately, real wires do have ends, and this means Ampere's law does not always give a good enough approximation for one's needs. Check out two videos that will take you through B-S for straight wires with ends, and one for a loop of wire with a current flowing (like the Helmholtz coil we used in the CRT lab last time).

Note that there is another video showing an example of B-S with multiple wires and currents, where we try to determine the B-field at some point from the two wires. If you need a review of B-S for moving point charges, there is a video for this here.

After watching the first two for wires, see if you can figure out the practice problems: Ch. 28 #59,60 for point charges (on page 7 of packet), and the collaboratives for wires on page 9 of the packet.

For Period 3:

Let's check out one video on defining the electric field some more. Take good notes on this since it will help with some of the problems we have coming up. Then, a second video will get into some examples of how to work with our formula for the electric field, E = kQ/r^2; you should take good notes on this one, too.

We will come back Wednesday and take a look at some examples of finding electric fields, and also electric potential, which is what we will call voltage.

We will try chapter 21, #66, 67, and 69; copies of these are in the packet you receive today.

Wednesday, February 15, 2017

Python Lesson for Wednesday

Hump Day!!!

Last week Fani was able to show us the importance and huge role of computer programming and simulations in science research. It is essential, and it is now a fact of life that if you do anything in STEM (and most other fields outside of STEM, as well), knowing even the very basics about what a program is, and how to manipulate existing code (not necessarily writing your programs from scratch) is invaluable and, frankly, expected.

We will do a bit of coding in Python throughout the semester, to expose you to this area of work.

The lesson for today is here.

First thing: In the computer lab, log into your student account and open the program Canopy. Do not click on it more than once - it will take several minutes for it to boot up. Canopy is something you can download for free on a home computer, and allows you to write and run your own Python scripts.

Tuesday, February 7, 2017

Earth's magnetic field articles

Check out a Scientific American article online, as well as a NASA article on reversals. Last but not least, a NASA article about the way the earth's magnetic field is constantly moving around and changing!

From your article notes and the video notes in class, summarize how scientists know all this, especially if there were no scientists around 800,000 years ago when the earth's field last reversed!!

Monday, February 6, 2017


We will try to bring back momentum, p = mv, from last year. Keep in mind two of the big things: it is a vector, and it is conserved.

To see WHY it is conserved, check out this video and take good notes.

Then, check out perfectly inelastic collisions that combine momentum with energy conservation, using something called a ballistic pendulum. Again, take good notes since it will help with some homework problems.

Tuesday, January 31, 2017

Ampere's law introduction

Check out an introductory video on something called Ampere's law, which has to do with the production of B-fields from 'long,' straight wires, long solenoids, and toroids. Ampere's law will be similar to Gauss's law for E-fields in the past.

Friday, January 27, 2017

For Today

Happy Friday, everyone.  :-) 

Periods 1-2, 5-6, and 8-9:

Check out magnetic forces on charged particles. A moving charged particle produces its own magnetism, which means magnets will make a force on that moving charged particle. This is where cross products start.

The magnetic force is F = qv x B.  Remember how to do the math for cross products (the 3x3 determinant thing), and that for A x B = C, the magnitude of C is C = ABsin(theta).

Check out two videos, one on the magnetic force on particles, and the second on an application called a mass spectrometer (along with a so-called velocity selector). Take good notes since you will need them for the practice set, which is the book problems and the first AP problem in the new packet you are receiving.

Period 3

We will be going into magnetism, so check out videos on this. First, watch and take good notes on an introduction to magnetism. A second video is on magnetic force. We will begin a lab with magnets on Monday, where you will get to begin (literally) feeling these forces, sometimes attractive and other times repulsive.

For practice and to begin thinking about magnetic fields, try the sheet you will receive. Use the side with diagrams to try and answer the questions.

Saturday, January 21, 2017

Scientists can watch an 'optical boom' with photons moving through material

For the first time, scientists can use high-speed videos (we are talking over one trillion frames per second...crazy short time intervals!) of a pulsed laser beam moving through a gaseous material to see the optical equivalent of a sonic boom. A sonic boom happens when a sound producing object like a plane moves faster through air than sound waves - we get a cone shaped structure of sound. The video in the link has a clear image of the cone-shaped pattern of light as the laser pulse moves at different speeds in a material compared to a gas layer that is also in the system. This is really cool!

Sunday, January 15, 2017

Here's Problem Solving/Engineering 21st Century Style - Agricultural MRI from Above

What a very cool application of high resolution photography, drones/airplanes/satellites, and computing - a UIUC professor has started a company that may be revolutionary for farmers to be able to identify issues in large farm fields (hundreds or thousands of acres). The company takes large numbers of photos of the farm fields, and then uses software it developed to identify even small areas within the field where there is an issue with disease, weather damage, lack of moisture, weed growth, and so on. In the past this has not been possible, and certain types of issues could spread to large sections of a crop before it was known - crop yields can only be improved using this technology and diagnostic technique. I personally love seeing creative, multidisciplinary solutions that can help make the world just a bit better!