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Friday, April 24, 2020

Quick links for Seniors, Week of April 27

Hope all is well!! Here are some quick links for convenience:
- For practice problems similar to this year's 2 AP exam problems
- For videos on just about any topic we do (focus on anything electricity related)
- For this week's review set, can be turned in (if hand written photos can be sent/shared)
- For old AP exams, solutions (logged in with eths202)
- For other review sets and solutions, quizzam solutions, can check any unit folders (logged in with eths202)
- For last lab

From College Board, for Students: Getting ready for exam day

Hope this helps!!

For this week, try at least 5 old AP problems on any electricity based topics you think are most beneficial for you - so think of the topics/problems that challenge you the most, and try them so we can be sure to figure out what's going on.  At least 2 of them should be lab-based. This is what will be put in HAC. Our sessions will focus on currents and circuits, so we'll be doing a lot of theory and examples together. 
We also have our last high school 'lab!' It is about charging objects by induction and conduction, and you figure out a way to do a demo/simulation for the task described in the lab. A 1-minute video explaining your method, by end of Sunday. You have 2 'phone a phriend' life-lines for this! 

Sunday, April 19, 2020

Seniors - 2020 AP Exam info & start of review

Here's the scoop, seniors.

All AP exams this year are 45 minutes in length, with 5 minutes needed to upload your work. For AP Physics C, both Mechanics and EM will have 2 free response problems (NO multiple choice). Go here to find more details on any AP exam you are taking. EM Exam at 1:00 PM on May 11. 

The first physics problem is 25 minutes and 60% of the score. It will almost certainly have multiple topics involved; it will be a bit more conceptual than just mathematical. While derivations are still fair game, it won't be completely math based. It is more difficult to BS one's way through conceptual questions than computational, so expect more writing than usual. Remember, they will likely want to have some calculus on the exam, and perhaps some derivation.

The second problem is 15 minutes and 40% of the score. It will be a lab-based problem. Perhaps you need to take a bunch of data and do an analysis. Or perhaps you will be given a list of available equipment and design an experiment to measure something specific. Keep in mind that a major piece of analysis is to have a mathematical model in mind, with a constant stuck in it, and you need to find the constant's value by using data - usually it involves linearizing a graph and using the slope to get the constant's value.

These exams are open book, open note! Go here to get advice about open book exams (these occur in college more frequently than in high school).

To find old AP problems that are similar to this year's problems, I will be putting the info here. You can find them in our AP Exam page on our school website. Any exam from the past decade will have lab based problems.

To me, it sounds like the AP Physics C problems this year will be more like AP Physics 1 problems. These tend to be more writing and explaining than hard-core calculations. The College Board gave as an example problem for the first problem, #3 from the 2017 Physics 1 examGo here to see past AP Physics 1 exams. Just focus on those problems that are on topics we study. The scoring solutions are available.

EM Topics for 2020: 
- Electrostatics: Point charges and E-fields, electric potential; F = qE, U = qV, Coulomb's law 
- E = -dV/dr, equipotentials, energy and work with charges
- Gauss & Non-Gauss
- Resistor circuits; R = pL/A (p = resistivity)
- Capacitor circuits; dielectrics
- RC circuits 

There is NO magnetism or EM induction this year!!

Review Set for the week of April 20:
- AP EM Review set I - Electrostatics to be completed by end of Friday, 4/24; solutions are on the 4 Chem/Phys page of our school site. Videos for all topics are here
- During our class Zoom sessions, we will take any and all questions, try some of the recommended problems together to best practice for this year. 
- Official class times: Mondays at 11 am; Wednesdays at 1:15 pm; Fridays at 10 am. 
- I've been doing 3 pm drop-ins on Tuesdays and Thursdays for juniors; will offer 2 pm drop-ins for seniors on Tuesdays and Thursdays as we get into review weeks! 
- Remember, using eths202 account you can access AP Exams and solutions

Saturday, April 18, 2020

Worth watching - Why social distancing and masks are effective

You should really watch at least the first minute or so of this video, showing experimental and simulated studies of what we all put out when we sneeze and talk. Droplets and micro-droplets, some smaller than 1 micron. It is really interesting technology to literally see the droplets, coming from work in Japan.


Micro droplets suspending in air from MixonK on Vimeo.

Friday, April 17, 2020

Happy Friday!!!!! Stay Positive!!

Remember, if you are reading this that means you woke up and are still kicking....it is a good day!!
Happy Friday!!


Tuesday, April 14, 2020

AP Exam 2020 Info and Resources

Here's the scoop, juniors.

All AP exams this year are 45 minutes in length, with 5 minutes needed to upload your work. For AP Physics C, both Mechanics and E&M will have 2 free response problems (NO multiple choice). Go here to find more details on any AP exam you are taking.

The first physics problem is 25 minutes and 60% of the score. It will almost certainly have multiple topics involved; it will be a bit more conceptual than just mathematical. While derivations are still fair game, it won't be completely math based. It is more difficult to BS one's way through conceptual questions than computational. Remember, they will likely want to have some calculus on the exam, and perhaps some derivation. Air friction tends to be the trickiest for most students. Go here to see some examples/reminders of where calculus comes in. Links to relevant videos are included.

The second problem is 15 minutes and 40% of the score. It will be a lab-based problem. Perhaps you need to take a bunch of data and do an analysis. Or perhaps you will be given a list of available equipment and design an experiment to measure something specific. Keep in mind that a major piece of analysis is to have a mathematical model in mind, with a constant stuck in it, and you need to find the constant's value by using data - usually it involves linearizing a graph and using the slope to get the constant's value.

These exams are open book, open note! Go here to get advice about open book exams (these occur in college more frequently than in high school).

To find old AP problems that are similar to this year's problems, I will be putting the info here. You can find them in our AP Exam page on our school website. Any exam from the past decade will have lab based problems.

To me, it sounds like the AP Physics C problems this year will be more like AP Physics 1 problems. These tend to be more writing and explaining than hard-core calculations. The College Board gave as an example problem for the first problem, #3 from the 2017 Physics 1 exam. Go here to see past AP Physics 1 exams. Just focus on those problems that are on topics we study. The scoring solutions are available.

Mechanics Topics: 
- Kinematics and 1-D, 2-D motion
- Newton's laws and circular motion
- Energy and work
- Momentum and impulse
- Rotations and angular momentum

There is NO simple harmonic motion or Gravity/orbital motion/flux this year!!

Sunday, April 12, 2020

3 Chem/Phys - Welcome back from Break!!! Finishing up

With hope you all had a fun, restful and healthy spring break, welcome back!!

What's new? What's been fun for you? What time have you been waking up the past week?

As we have at the very least a few more weeks of remote learning, 3 BIG reminders:
1. be checking in with attendance each day with the school; your teachers have no choice but to go by the official list we receive, regardless of whether we see you on Zoom or get emails from you on a given day
2. remember that counselors, social workers, and psychologists are all available if you need anything personally, for college, or any other school matters. 
3. there is the sharing Google Sheet, to give ideas of things to try

AP Details for Mechanics: 
- will be at 11:00 AM on May 11
- 2 problems: the first you will have 25 minutes to read and write your responses (60%), similar to #3 on this AP 1 exam; and a second one you will have 15 minutes (40%).
- you can use a calculator
- just free response, NO multiple choice
- a lot of conceptual understanding will be tested, some calculations/derivations possible. The second one will be to design and analyze a lab experiment on some topic.
- No simple harmonic motion/oscillations, gravity and orbital motions
- Once you submit the first problem you will not be able to go back to it.
- Go Here to get details of any AP exam for this year

Completing the Course:
To hopefully have something a little different and physical, try to do a few of the options in this at-home mini-lab for rotations. Depending what you have available at home, try at least 3 of the options in the lab by the end of Friday, April 17. These are just some fairly simple things to do. For instance, if you happen to have any hard boiled eggs, there is one quick option for those and raw eggs.

Even though it will not be on the AP exam, today just a brief introduction into simple harmonic motion (SHM). The standout example of SHM is something oscillating on a spring. The gist of this will be using F = ma = -kx to give us our one case of a second order differential equation (a is the 2nd derivative of position). Of course, this is different from things we've already done, such as with basic motion or air friction, which have all been first order differential equations that we can do an integral (antiderivative) to solve.

For our 2nd order DE, the solutions for functions of time will be sines and cosines. Hopefully this makes sense, if you want to describe a periodic motion mathematically, we should probably use periodic functions, and those happen to be the solutions to what Newton's 2nd law gives us for a spring.

Relevant Videos: 
Because we won't do all of SHM like we normally would, relevant videos are linked here for those who are interested. For those who have an interest in learning all of SHM, I can do some other examples on Tuesday's 3 pm Zoom session.
- simple harmonic motion, the basics
- SHM more details: initial conditions and phase angle
- simple pendulum and small-angle approximation
- more advanced: SHM for a stick oscillating due to a spring (rotating, oscillating stick)
- a 1-D example of the Schrodinger equation to see where quantum numbers (integers) come from!

Lab: PhET Simulated Experiment for SHM: if you want to vary parameters and see the effects on the oscillations.

There is a simple harmonic motion packet in our SHM folder of the 3 Chem/Phys school web site. There are some recommended practice problems for those who want to try any. These will not be 'assigned' since we won't need them for the AP exam. We will do a couple together as examples, so you can see what all this is about.

AP Review Materials: 
Review sets are all available on the 3 Chem/Phys site. There are three sets to get the basic ideas back for the material that is fair game for this year's AP exam:
AP Review Set I 
AP Review Set II
AP Review Set III 
Each has solutions files available, and we had some of these for the review for the 1st semester final.
All of my videos are here.

And then the AP Exam page. You need to be logged in to your eths202 account to access.

The College Board has online review sessions for all AP courses.



Tuesday, April 7, 2020

Iron rain....really, I'm serious!!

Nature never ceases to amaze, as humans look around more and more, there are ever more surprises. This one caught my eye - astronomers have found a planet called Wasp-76b, some 390 light years away (which is really close!). It is a "hot Jupiter" planet, meaning it is big, nearly twice as big as Jupiter, in an orbit really close to its star. The sunny side is over 4000 C, which is hot enough to melt and vaporize iron. Any iron in the atmosphere, such as iron dust, melts and actually can become an iron vapor! Now, as the planet rotates, on the dark side of the planet, it is cool enough for that iron vapor to condense and form droplets heavy enough to fall...this planet should have iron rain!! I don't know if anyone has ever come up with this idea in any science fiction, but now it looks like the strangeness and creativity of nature never lets up!

If someone is looking for something to do over spring break and our isolation, change the lyrics of "Purple Rain" (by Prince), and make a new song, "Iron Rain."  😉