Darfur

Nice work guys. Today's collection was nearly $100. Congratulations but don't stop now.

To All Students: This Physics Club Meeting Addresses All you Need to Know About (AP) Physics

Come to tomorrow's Physics Club Meeting - Thursday 7AM room 506.

How about a 30 minute review of a year's of physics. Vanessa and Sandra can do it--- or so they say. Come on time if you can and see if they can really pull this off.

Honors Assignment

Quiz is Friday. For tonight, fill out this table

http://h1.ripway.com/DrCherdack/oscprobA4-09.xls

and this one

http://h1.ripway.com/DrCherdack/Pendulum%20problem1.xls

Cosmic Ray Class

Rutgers is holding a class on using cosmic ray detectors ( we have 4) on Saturday May 15. We will learn new ways to use the detector and how to join a network dedicated to detecting cosmic rays from hugely energetic events. Please contact me ASAP if you would like to attend.

Honors Pendulums

The maximum PE for a pendulum occurs at maximum displacement from the equilibrium, where equilibrium is the bottom of the arc. This PE is simply mg hmax where hmax is the height at the ends of the motion.

Read the notes in the link to see that PE max = E total = Mg x phimax^2 L
http://h1.ripway.com/DrCherdack/Pendulum%20Energy.doc

Honors Lab on Harmonic Motion

This lab can be informal but the discussions and conlcusion must be more than just answers to the questions. Also, make sure you do the post lab.

AP X rays

Electrons can produce x rays when they interact with matter consisting of atoms with large numbers of electrons. They give up their energy rapidly, emitting x rays comparable in energy to their own original KE.

Darfur Solar Cooker Collection

This fund raiser represents a chance to help both people and the planet. Solar cookers mean less damage to forests and less misery for the refugees. Our take today was only $24 mostly thanks to one generous soul who donated $10. We have collected only about $85 total and $50 of that came from just three donations.

Lets step it up. We should be averaging about $50 a day. That's only 50 cents per person per day.

T Shirts

It has come to my attention that many of you are making the serious mistake of only ordering one physics crew T Shirt. You are not taking advantage of our special 2 for $26 pricing or our even better 4 for $52. Order promptly so we can ensure delivery well before our trip to Six Flags.

More on Juniors Interested in Physics

It just gets better. Here is a little more info. It runs from 6/28 to 8/6

We'll likely start each morning at 9:00 and end at 3:00. I don't have a syllabus. Here is a brief description of what the students will be doing from Dr. Schnetzer.

"For the summer, you will be primarily working on developing cosmic ray detectors. This summer we plan to begin deploying a large array of counters for detecting very high energy cosmic rays. You'll also get some experience with our work on CMS which is one of the two large detector facilities built for the Large Hadron Collider (LHC) at CERN. The first data from the LHC is coming in and I'm hoping that the students this summer can get some experience looking at this data. We'll also have daily extended lunch discussions where we will go over a wide range of physics topics. Once a week there will be a guest presentation by someone in the Rutgers Physics Department. You will be working with seven other high school students. Two high school teachers will also be working in the program. Four Rutgers faculty members (Yuri Gershtein, Ron Ransome, Eva Halkiadakis and myself) will supervise the program."

Prom

It was most impressive to see how elegant and sophisticated you all looked at your prom. I hope you all had a great time. Mrs. Cherdack was also impressed by your appearance, but we were both even more impressed by your enthusiasm, behavior, and cheerful spirits, and the goodwill you show each other.

NHS

A few of you have asked me to write appeal letters about NHS. I need to know which categories my letter must address and information supporting your qualifications in those categories, particularly things outside the class. That optional bio assignment would come in handy now right. Send me all this ASAP!!!

AP Goals

Here is what the College Board has set for the goals for this course. You are expected to know the stuff in the column for B physics. Unfortunately, it pretty much tells you what equations and examples with which you should be familiar, rather than emphasizes understanding. The exams and the grading policy are somewhat better than this document in this regard. In any case, you should look this table over carefully and make sure you can handle the majority of this stuff pretty well.

http://h1.ripway.com/DrCherdack/ap05_phys_objectives.pdf

AP Students 3 items

1) I have been looking over some of the free response tests from the break package. We will be going over them in class. I hope many of you have gotten over whatever laziness and distractions (break and prom, for example) were interfering with your performance and are now ready to produce a real effort for the next two weeks. You will need to consolidate your knowledge and firm up your understanding by two weeks from tomorrow. You must show the maturity to put in the effort to accomplish this. Someone's paper complained of not being able to understand the questions, as if it were the questions' fault. The paper had no name on it.

2) Some of you did not bother writing the MC test # ( 2 or 4) on your scantrons. I will not score these. These were meant to be practice and were not graded as tests by me, but are a means to gauge where you are in your preparation. If you got someone else to provide answers to the questions you wasted everyone's time and diminished my opinion of you.

3) I asked students to email me with preferred afternoons and/or mornings for review sessions. So far one response. You folks certainly need more review than class time will afford, especially with AP exams in other subjects interfering next week. Unless I get a flood of emails by 2:30 Monday the schedule is Monday, Tuesday, and Friday afternoons and Tuesday mornings for the next two weeks.

All Juniors Really Interested in Physics Urgent

I have just learned of a fantastic opportunity for juniors interested in physics. Rutgers is holding a summer school, and here is the information I received from Dr. Schnetzer Friday.

"I learned this past week that Rutgers have been officially funded by QuarkNet to host a summer research program again this year. This will be a six week program in which the students will get hands on experience with cosmic ray detection and with our work in high energy physics. I know that you [ that means me] were interested in sending some students to this program last year but we were already full up so I wanted to give your students first priority this year. Please let me know if you know any who would be interested. We'll run from June 28 to August 6. Students receive a stipend of $1960 for the six week period. "

I need expressions of interest from you ASAP!!!

Honors Schedule

Ignore the oscillator problems A 4-9. That was replaced by some text problems. I'll have to check my notes in school tomorrow to find out which ones should have been in the schedule in addition to 1 and 3.

I hope this error didn't cause too much concern to students such as Ashley or Mel.

Honors Schedule for Oscillations ( Harmonic Motion)

Here it is

http://h1.ripway.com/DrCherdack/HonUnit11harmsched10A.doc

http://h1.ripway.com/DrCherdack/HmwrkonOscillsWaves2-08.doc

http://h1.ripway.com/DrCherdack/RevProbRotandHarmR2.doc

AP Optics Test

I have just finished grading your test and the results are somewhere between discouraging and disgraceful. They show the persistence of trying to memorize meaningless formulae without understanding and a lack of attention to what was done in class. I suppose I share the blame for this since while my notes emphasize the ray diagrams, they also analyze the situations using the 1/f =1/do + 1/di formula. I tried to rectify that in class, but I guess without much success.

The subject can be largely mastered by drawing three rays, and the use of two sets of similar triangles. It is a simple subject, at least to the depth required of you.

Many of you got correct answers by plugging into a formula which was completely unjustified based on your diagrams. No matter how many times I showed you the reason why images get larger or smaller only a few of you used the distance from the object to the focal point as the major consideration.

Many of you do not understand that images are formed where rays from a part of the object converge with other rays from the same part, or at least appear to do so. An unreasonably large number of you cannot identify the three rays we used and their paths.

An unacceptably large number of you didn't even locate an image although the questions specifically asked you to do so.

Many of you determined that the image height of 24 cm was diminished from an object height of 12 cm. Thinking that 24 is smaller than 12 is a new level of misunderstanding.

Most of you quoted another formula involving inverse sin rather than think that

ncrystal sin theta critical = nglass sin 90deg so ncrystal = nglass/ sin theta critical.

Too often, you are still answering examples instead of solving problems.

I have updated the notes and summary although they still use the formula too much. I urge you to use hi/ho = f/|do-f| for converging mirrors and lenses and hi/ho = f/|do+f| for diverging lens and mirrors. Many of you used f/|do+f| for converging which is wrong.

http://h1.ripway.com/DrCherdack/NotesonGeometricOptics4-10.doc
http://h1.ripway.com/DrCherdack/SummaryofGeoOpticsrev4-10.doc

Special Greeting

Hello to Miss Rosenberg who stopped by after class today, even if it was only because her game got canceled by lightning ( physics triumphs over sports) and she had to stay for forensics ( talk triumphs over all else around here).

AP Schedule

Here it is, the moment you've been waiting all your lives for (well maybe not, but here it is anyway) the Modern Physics Schedule!!!


http://h1.ripway.com/DrCherdack/AP%20Unit%2015%20ModPhys%20schd%2010A.doc

Honors Rotational Motion

We will begin our study of oscillations and waves with a review of rotational motion. Please review the following notes tonight and answer these questions by Thursday.

http://h1.ripway.com/DrCherdack/Rotational%20Motion%20Defns%20etc.doc

1) A wheel makes five rotations in every 3 seconds, what is its omega?

2) If the wheel in problem 1 is .25 m in radius, how fast is a point on its rim moving?

3) What is the change in angular position ( i.e. delta theta) for the wheel in 12 seconds ?

4) If a wheel is .35 m in radius and has an angular acceleration .35 radians/s^2, what is the tangential acceleration in m/s^2 of a point on the rim?

5) What is the displacement of a point on a blade on a turbine/generator with a radius of 1.2 m after five full rotations. What is the distance it traveled?

Physics T Shirts

The Physics Club is selling T shirts. Not only are they the latest fashion statement and a real bargain, but it is almost guaranteed to add 10 points to your score if you take a test while wearing one.

A bit more seriously, it would be pretty cool if all Ridge students wore these to Great Adventure.

In any case if you want one see the link:

http://h1.ripway.com/DrCherdack/Support%20Ridge%20PhysicsTshirtA.doc

everyone: Read the following and bring in the loot

Got this before the break and now is your chance to shine. Its a chance to redeem yourselves after the lackluster performance on the food drive. And don't be doing this just for the bagels.

The Save Darfur Club is running a fundraiser to buy Solar Cookers for women in Darfur. For those teachers that teach a first period class we would like to put a container in your classroom for donations. The class that is able to collect the most money at the end of 2 weeks will win a bagel party from the Save Darfur Club. This fundraiser will begin on April 19th and end April 30th. Thank you for your help. It is greatly appreciated.

AP Magnetics Lab

Many of you mistakenly invoked Faraday induction ( or the form of it known as Lenz Law) in this lab. This is very wrong. The current in the solenoid was produced by the voltage difference across the solenoid which in turn was caused by connecting it to a battery. The chemicals in the battery produce the voltage difference between the terminals which when connected to the solenoid cause the current to flow. Note that only one solenoid was connected. The second solenoid was used only as dead weight to come close to balancing the first solenoid.

Faraday induction and Lenz Law both involve changing magnetic fields, i.e. fields that vary with strength or direction as time goes by. A constant field produces no EMF and thus no current. The permanent magnet was being held relatively still and thus was not capable of inducing much current. Make sure you understand this!

AP Some Optics Derivations

Here are some derivations I skipped in class but you may have already gotten from the notes:

http://h1.ripway.com/DrCherdack/Derivoffforsphmirr.doc

http://h1.ripway.com/DrCherdack/Derivlenslawsphmirr.doc

Modern Physics for AP

Here are the links. Use both of them, not just the summary. It should help you with several of the AP test questions.

http://h1.ripway.com/DrCherdack/ModernPhysicsReview.doc

http://h1.ripway.com/DrCherdack/ModernPhysAPSummary08.doc

Honors Project Presentations

I decided to give you a break. Section 1 (S1)groups need only review all Sect 1 presentations except that each group has to review the same group's presentation in the other section. Same for Section 2: review only Section2 (S2) presentations except for your own area where you must review the section 1 presentation.
Your assignment now is: Each student is responsible for having learned the material taught by other groups in her/his sections and for his/her own area from the other section.
-write a summary each of the other group's work as presented

-meet at least once,
-make progress on at least two of the points you identified as needing further work, each student is to report that progress individually, i.e. describe what new stuff you learned. This will be graded so do a good job.

http://h1.ripway.com/DrCherdack/First_WallS1Pres1.ppt
http://h1.ripway.com/DrCherdack/FirstwallS2pres1.ppt
http://h1.ripway.com/DrCherdack/GeneratorsS1pres1B.ppt
http://h1.ripway.com/DrCherdack/generatorS2pres1.ppt
http://h1.ripway.com/DrCherdack/HeatingS1pres1B.ppt
http://h1.ripway.com/DrCherdack/HeatingS2%20Pres1Revised.ppt
http://h1.ripway.com/DrCherdack/HeatingS2%20Pres1Revised.ppt
http://h1.ripway.com/DrCherdack/magneticS1Pres1.ppt
http://h1.ripway.com/DrCherdack/magneticsS2pres1.ppt
http://h1.ripway.com/DrCherdack/PlasmaSect1Pres1MU(1).ppt
http://h1.ripway.com/DrCherdack/PlasmaS2Pres1.ppt
http://h1.ripway.com/DrCherdack/ThermoS1Pres1.ppt
http://h1.ripway.com/DrCherdack/ThermoS2Pres1.ppt

Grades, etc

Well I got my grade spreadsheet but I cannot download other files yet. Thus I cannot review or post your presentations your yet. Thy are having drive problems on ridgenet.

Everyone

Here is some info for now. Stay tuned during the break for further communications

1) Ridgenet is down so I cannot work on your grades . I'll let you know when I can get back in to my files/your grades.

2) Honors: I cannot post the honors presentations now, but when I do, go through them. Each student is responsible for having learned the material taught by other groups in both sections. Your assignment for the break is to

-meet at least once,

-make progress on at least two of the points you identified as needing further work, each student is to report that progress individually, i.e. describe what new stuff you learned. This will be graded so do a good job.

-write a summary each of the other group's work as presented.

3) AP do the tests and use MC 4 as part of the practice test. Do the problems and reading as called for in your schedules.

4) research: We will continue with solid state presentations when we first meet and then move into general relativity, the next meeting. Stay tuned as I may post some reading for you.

All students: Read the Following and Bring Cash

A chance to redeem yourselves after the lackluster performance on the food drive. And don't be doing this just for the bagels.

The Save Darfur Club is running a fundraiser to buy Solar Cookers for women in Darfur. For those teachers that teach a first period class we would like to put a container in your classroom for donations. The class that is able to collect the most money at the end of 2 weeks will win a bagel party from the Save Darfur Club. This fundraiser will begin on April 19th and end April 30th. Thank you for your help. It is greatly appreciated.

Study Group Reports

This is what my records show as of Tuesday. If you are in Honors 2 and turned in any reports on Monday or Tuesday they may not be in here yet, but otherwise they should be okay.

Make sure you are up to date by Friday and ALWAYS include the topic in your report.

http://h1.ripway.com/DrCherdack/Group%20Reports3rdqrtr4-1.xls

Field Trip

1) My records, i.e. overflowing pile of loose papers, show following of my honors students have decided not to play hookie, I mean engage in an intense learning experience at Princeton Plasma Physics Lab tomorrow: Kristie Wei, Kelly Scott, Julie Sandelovsky, Katie Twillman, Kathleen Kirk, Melissa McGurl. If you are one of these people and are planning to go contact me immediately. Otherwise be good during 6th and 8 th and do what you are told. Remember, my spies are everywhere. You can use the laptops if no one has pinched them.

2) AP kids, I 'm going to Princeton Plasma Physics Lab tomorrow and you can't come. So there. Behave yourselves, do the worksheets, see remark above re: spies.

3) Honors research you can use the laptops if no one has pinched them.
Please check to see all of them are shutdown.

Honors Fusion Reserch Web Site

Here is a web site that may help out some of you particularly first wall groups

http://www.ornl.gov/sci/vlt/index.shtml

AP Unit 14 A practice Problems Solutions

Not sure that better late than never applies here but here they are. They may even be correct ( I am pretty tired).

http://h1.ripway.com/DrCherdack/Unit14APractProbwsoln.doc

AP Optics Unit

Here is the schedule for Unit 14 B. Its probably mostly right.

http://h1.ripway.com/DrCherdack/APUnit14BLightsched-10.doc
http://h1.ripway.com/DrCherdack/NotesonGeometricalOptics.doc
http://h1.ripway.com/DrCherdack/SummaryofGeoOpticsrev3-07.DOC


http://h1.ripway.com/DrCherdack/Unit14problemsheetr1.doc

AP Problem Sheet

There seems to be an error in the third answer for problem 11. It should be 625 nm not 675. Courtesy of Tom Coto.

I may get to post answers to the practice Problems tonight, so you might want to check.

AP Period 1 and 2 No Gridding Tomorrow

Ms Shaddis has graciously consented to come to 506 on Wednesday to help you pre-grid so that we can spend tomorrow together for 2 periods. Iwill be out on Wednesday on a field trip.

Honors and AP Labs

See me s that have not been addressed and resubmitted will become 50 s. There are many zeros for labs right now. Labs are pulling down grades for almost 1/2 of the honors students and a handful of APs. Lab grades were supposed to help raise your grades from your test score level, not reduce them.

ALL HONORS AND APS

Study group reports are REQUIRED for each unit. Get them in by Thursday or suffer the consequences.

Honors Slides

I have reviewed all but one of the presentations you sent by email. Distribute them to your group members. You folks will be presenting Tuesday, Thursday, and Friday. Any volunteers for Tuesday? The earlier presentations will be graded more leniently.

Honors thermo Test

Results were generally significantly better. There was a big increase in the number who can find work done by a process represented by simple path, but a lot of the improvement came in the plugging and chugging.

Remember the primary goal of thermodynamics is to see how to convert thermal energy into work of a mechanical nature. Most of you showed you can find work for a simple case and many of you handled the tough adiabatic realtions between volume and pressure quite well. This is real progress and we have accomplished a lot.

Too many still cannot figure out what must happen to Q, W, and U for a given type of process (the first four questions).

Many of you had adiabatic expansions in problem 1 with rising temperatures and increased U. Where did this energy come from? How could an expanding gas do work ( as an expanding gas must) and gain energy rather than losewhen no heat was added?

Too often, you are still not thinking about energy conservation . You are just recording whatever results you get from hitting ( often the wrong) keys without understanding their meanings and implications.

Not enough of you showed that work out must come from loss of U in an adiabatic process, i.e. Wout = - delta U

Too few got the heat transfer problem right despite having the equation in front of you.

Some of you are still confusing R and k. Volume of 10^29 should be a tip off that you've made an error.

AP test on magnetics

Grades were pretty good but your papers still show more facility with plugging into formulae then with understanding ideas. Lots of errors in the figure MCs and lots of really wrong stuff in the problems. For example:

1) many of you used whatever linear dimension you could get your hands on in F= IL x B. The L is of course the length of the wire carrying the test current that is in the magnetic field produced by the source current.
2) Some of you used the source current in the above equation. Using the source current and the field from the source current is like trying to find the force of the current on itself.

3) In the extra credit, many of you tried to use the solenoid equation on the current produced by the beam to find the field that was need to ACT ON THE PROTONS in the beam. Those of you who made this mistake are using the test particles as if they were the source of the fields acting on them. It should be obvious that the current is not causing itself to turn in circles. The beam of protons is in a field created by much stronger currents and it is this field causing the protons to bend their path. The solution is found from equating M acentripetal ( i.e. M v^2/r) with the magnetic force QvB to get Mv/r = QB and solve for B

4) perhaps even worse was trying to use the Faraday induction FORMULA to find the voltage it took to accelerate the protons up to speed. This class is NOT THE FORMULA OF THE MONTH CLUB. First of all the constant magnetic field can only change direction not add speed, and if the field is not changing why would there be an EMF. Second of all you should know that delta KE =- delta PE and that PE is equal to QDeltaV or Mv^2/2=QDV so DV =(M/Q )(v^2/2)

5) In the equation for EMF you should know that N means how many windings or turns the coil consists of NOT how many rotations it makes while moving. When will you start thinking and stop memorizing jumbles of letters?

AP Unit 14 A problem Sheet

Here is the missing sheet. Looks like not many of you started doing your homework for tomorrow.

http://h1.ripway.com/DrCherdack/Unit%2014A%20probsheetR2.doc

AP Break Assignment

I will be distributing a large assignment for the April break. It will be the equivalent of one test and 6 homeworks on your grade. Make sure you see me if you plan to not be in class on Friday 4/9.

Honors Two More Items

1) Field Trip : I do not have slips/money from about a dozen students. Bring both in Monday.

2) Project Assignments. I am missing about half the outlines/6 slides that you were supposed to turn in on Thursday. Email me any files you have ASAP before Monday to get credit for them. While I hate to keep using grades as a motivator, if you have done a good job on your projects it will affect your grade by replacing some points that come from categories where you have done worse.

All students

For many years room 506 was a pretty safe haven for items whose value ranged from a few cents to several hundred dollars. This has come to an end. Calculators have disappeared and many other items. The latest two are a TI 89 left during 4th period early this week and a Tupperware container removed from its owners desk during 8 th period. Please return these items on Monday.

Lets try to keep 506 a source of good memories.