Honors: Two items

1) Permission slips and checks are due tomorrow for the field trip.

A reminder from an earlier post.
"The cost is $16 each payable by check made out to Ridge Student Activities Fund - Physics (or small unmarked bills in non sequential serial numbers). Bring or buy lunch at the lab. we could use another adult or two so see if one of your folks would be interested in going.

Here is the info from the lab. make sure you are in compliance.

" "Your tour of the Princeton Plasma Physics Laboratory (PPPL) for about 42 Ridge High School students is scheduled for Wednesday, April 7, 2010 at 9:30 a.m. Please send me a list of the students and others prior to arrival. Non-U.S. citizens must provide the following information: citizenship, date of birth, and place of birth on the list. Your group will dine in the Cafeteria following the tour.""

2) Here are the solutions for the cycles given as homework last week. Be prepared to do some cycle analysis and heat transfer work on the quiz tomorrow. You should know the meanings of the four types of processes and their implications with respect to Work, Qin, and DU. Also recognize that a real process can fit in between or outside the 4 main types. Also know about

efficiency = net work out/gross heat in.

See you folks tomorrow.

http://h1.ripway.com/DrCherdack/Cycles%203-23-10%20slns.xls

AP PreGriding

AP Section on i.e. second period class will do pregridding on in 506 during 2nd period on Wednesday so we will have the two periods together on Tuesday.

Honors Solutions to Chapt 14

Here are solutions to Chapt 14 prob 31, 39, 42, 65 both via link and included here ( but all symbols and exponents are messed up so use the link if you can)

http://h1.ripway.com/DrCherdack/Solutions%20to%20Giancoli%20Cha.doc



Solutions to Giancoli Chapter 14

31. Qin = ΔU Lf ΔM where Lf is the heat of fusion ( i.e. the energy it takes to melt one kg.) and DM is the mass melted.

DM = Qin/Lf but Qin = 0.50 x |ΔKE| = .50 Mvinitial 2/2 = 0.50 x 54 x6.42/2= 553 J and Lf = 3.34E5 so ΔM = 5.53E2/3.34E5 = 1.66 E-3 kg.

39. heat flow through the copper = heat flow through the copper = heat flow through the aluminum = total heat flow so
= ΔTcopper kthermal conductivity of copper A/L = ΔTaluminum kthermal conductivity of aluminum A/L
ΔTcopper = 250 –T and ΔTaluminum = T-0 the As and Ls cancel so we have

(250 –T)kthermal conductivity of copper = T kthermal conductivity of aluminum

gathering terms in T to the right side we have

250 kthermal conductivity of copper = T(kthermal conductivity of copper + kthermal conductivity of aluminum)

or T = 250 kthermal conductivity of copper / (kthermal conductivity of copper + kthermal conductivity of aluminum).

42. Using notes on thermal conductance I provided I have R equiv = R1 +R2.

ΔQ/Δt = (Thot-Tcool) xA x k/L = (Thot-Tcool)/R . However the book uses R differently from me and I should have warned you. The book uses R as resistance for a wall with an area of one unit of area. Clearly the heat conductance of a wall is proportional to the area ( bigger area wall has more heat flowing through it) and since resistance is simply 1/conductance, the resistance ( R as I use it) goes as 1/area. So the R-19 which is in US units needs to be divided by the 240 square feet to get the R as I use it.


Thus we have Rbook for brick is about 1 ( page 397) and for the insulation Rbook is about 19 for a total of 20. Dividing this by the area gives an RCherdack of 1/12 (deg F hr/Btu).

So ΔQ/Δt = 12F /(1/12) =144 Btu/hr or .27 J/s [1Btu = 1050 J; 1 sec =1/3600 hr].

65. Q = McΔT= 185 kg x4186x40; Δt = Q/Power, since power is energy /Δt

AP Lightwaves Schedule

Here is the unit 14A Schedule. Make sure to read the notes: Physical Optics Summary. They will help.

http://h1.ripway.com/DrCherdack/APUnit14Asched10.doc

http://h1.ripway.com/DrCherdack/PhysicalOpticsSummary08.doc

Honors Assignments

Your assignments come in 3 flavors
1 - worksheets and text assignments to prepare for thermo quiz on Thursday ( in school work and first text assignments)
2 - project oriented text assignments

3- start on your first project presentations ( which will be made next week).

Details are below

Honors Text Assignments:

1 - Thermo Quiz prep

All : Due 3/29 Reread all of Chapt 14 especially Sect 1,2,3 and 6.

Answer questions 17,21, do probs 21, 31, 37, 39, 42, 65 refer to your thermo schedule sheet for some of the equations you’ll need. For prob 42 see Heat Conductance Derivation (posted today)
http://h1.ripway.com/DrCherdack/HeatConductionDerivationr2.doc
and realize that

DQ/Dt = DT x conductance = DT / resistance and conductance = kA/L and resistance, R = (1/ conductance) = L/kA.

Study for thermodynamics quiz on heat transfer, processes, and cycles on 4/1

2- Project Text Assignments

Note you may have to read earlier chapters to understand the readings.

First Wall Groups:

Due 3/30 - Read Text Sect 9-5 Do Chapt 9 probs 38, 39,

Due 3/31 Read Sect 9-6 Do probs 49,51,45

Thermo groups:

Due 3/30 –Reread Text Chapt 15 Sect 1,2,4,. Do 1,3,5

Due 3/31 –Reread Text Chapt 15 Sect 5,6. Do problem 9,10, 17,23,35

Heating Group:

Due 3/30 Reread Chapt 16 Sect 1-10 don’t worry much about more than 1 direction ( i.e. 2D vectors).Do prob 5, 23 ,31,43.

Due 3/31 Reread Chapt 17 Sect 1 through 6 and 10. Do prob 1, 3, 65 ( find vy and use inverse tan to find theta.)

Magnet Groups:

Due 3/30 Reread Chapt 20 Sect 1 through 5. Do 1,7, 11,

Due 3/31 Reread Chapt 20 Sect 6 through 8 and 11, 12. Do49, 51 (really do it including explanations), 61

Generator Groups:

Due 3/30 Read Chapt 21 Sect 1 though 5. Do 1,5,11,16

Due 3/31 Read Chapt 21 Sect 7,9,10,11. Do 20, 25 ( read up on rms),39, 45.

Plasma Group:

Due 3/30 Read pg 872 –875 Read Chapt 10 Sect 1 through 3

Due 3/31 Read photocopied notes up through at least drifts.

Do following What is v drift for a deuterium nucleus with v perp = 3E6 m/s in a field of 5T into the page if the field strength changes by 1T per m to the left. Is it up or down? Find v drift for the same nucleus with v perp = 3E6 m/s if B = 4T into the page if there is an electric field of 20,000 V/m upward. Be prepared to discuss why we need a poloidal field.

3 Project Work

Due Thursday 4/1: An outline of your first presentation to be made the following week and six slides from your presentation. The slides should identify major system and phenomena and contain at least a few fundamental equations.

Honors Field Trip

We will be going to Princeton Plasma Physics Lab on Wednesday April 7. Permission slips will be available in the out folders. The cost is $16 each payable by check made out to Ridge Student Activities Fund - Physics (or small unmarked bills in non sequential serial numbers). Bring or buy lunch at the lab. we could use another adult or two so see if one of your folks would be interested in going.

Here is the info from the lab. make sure you are in compliance.

" Your tour of the Princeton Plasma Physics Laboratory (PPPL) for about 42 Ridge High School students is scheduled for Wednesday, April 7, 2010 at 9:30 a.m. Please send me a list of the students and others prior to arrival. Non-U.S. citizens must provide the following information: citizenship, date of birth, and place of birth on the list. Your group will dine in the Cafeteria following the tour.


Please be advised of the following for the tour:


l Cameras and tape recorders are permitted and encouraged.
However, no briefcases or packages are allowed on the tour.

l No high-heeled shoes, open-toed shoes, or sandals.


l Radiation monitoring may be performed of your group
as per Department of Energy (DOE) requirements.


l Hard hats will be provided if you enter areas where they are required.


l No children under the age of 12 will be permitted on the tour.


Additionally, as a federal facility, we are taking heightened security measures at PPPL. Upon arrival, all adult visitors must show a government-issued photo I.D. This could include a passport or a driver's license.
Non-U.S. citizens must show a photo I.D., plus give us the following information: citizenship, date of birth, and place of birth.
For the welfare of both our staff and visitors, PPPL security staff retains the right to inspect vehicles and personal packages such as briefcases, satchels, book bags, and purses.

Groups begin in our main office building - the Lyman Spitzer Building - and after an introductory presentation, walk to the experimental areas. This is about 1/3 of a mile round-trip and includes several stairs. If you will need special accommodations for getting from our main office building to the experimental site, please let me know ahead of time. We look forward to presenting our program on fusion and talking about the research being conducted here at the Princeton Plasma Physics Laboratory. Maps and directions to our Laboratory are available on the web at http://www.pppl.gov/visiting.cfm"

Thermo for Honors but great practice for AP too

Here are a couple of cycles to solve. Have them ready for class tomorrow if you can possibly can do them.


http://h1.ripway.com/DrCherdack/Cycles%203-23-10%20-1.doc

Take a look at this but don't sweat the detailed derivation of P x V^gamma =constant

http://h1.ripway.com/DrCherdack/Notes%20on%20Basic%20Gas%20Thermofor%20nmoles.doc

Labs, AP and Honors

Lab purposes are almost always to confirm some conclusion about physics we have reached based on observations and derivations, often expressed as an equation.

For example, for Archimedes' the purpose should have read something like: to confirm that FB = density of fluid x g x Volume of object submerged. We can confirm this by using the volume found from this equation to determine densities and find they are the same as the accepted values. Also to confirm that FB is the same as the rise in pressure(density of fluid x g x delta h) x area of beaker.

Conclusions must address purposes and if they were accomplished.
By the way, we did not use the apparent weight ( Mobject xg - FB) anywhere in this lab and those who brought it up in their reports were simply misquoting books without understanding what we did in the lab.

For the AP field plotting lab, many of you drew curve shapes you thought should be true with no regard for whether or not the values of V on your supposedly equi-potential curves were equal. This is the worst kind of misunderstanding. If you are going to make your conclusions fit your your preconceived notions and not the data, politics or sociology is for you, not physics.

Also on AP field labs; since V=E dot d where field is strongest V changes the most rapidly so if equipotential lines are say .5 V, apart they will be closest where E is greatest. E is greatest where the field lines concentrate ( the more line per area the stronger the field). So the field and equipotnetial lines are densest in the same region.

Electrostatics labs: protons don't move in solids, electrons move in conductors and semi conductors and a little on surfaces of insulators and between objects in contact.

For many labs many of you either think incoherently or can't be bothered to take the time to write coherently; either way it makes for bad lab reports. Please think carefully about both what the lab showed you and how you will write about it.

And finally: labs more than ten days late are zeroes from now on

AP Magnetics Schedule

Here are the Unit 13 materials: [Its R8 for Notes on Magnetics despite what schedule says]

http://h1.ripway.com/DrCherdack/AP%20Unit%2013%20Mag%20sched10.doc

http://h1.ripway.com/DrCherdack/Notes%20on%20magneticsR8.doc

http://h1.ripway.com/DrCherdack/Unit13Worksheet1.DOC

http://h1.ripway.com/DrCherdack/Unit13Worksheet2.doc


http://h1.ripway.com/DrCherdack/Unit13ProblemSheet.doc

AP Assignment,

Since the quiz is tomorrow, do the Currents Practice Problems tonight. Also group reports are due.

Hall Passes

Mr. Howlett has announced that hall passes are being stolen at an alarming rate. This is consistent with the rate of other thefts. Be advised that stealing passes is, and will be treated as, theft. I am hoping that this is irrelevant to all of you.

Optional Assignment Bio/Resume

This is usually a required assignment but I'll make it optional this year.

Write a short bio telling me about yourself, your interests, what you do in and out of school, your philosophy, how you help your friends, family, community, etc.

Due Friday

AP Resistance and Conductance

We spent most of today talking about conductance whereas resistance is what is used most of the time. Since currents are the desired product I believe it makes more sense to think in terms of what makes a current flow rather than what prevents it. Resistance is merely the inverse of conductance. Instead of I = delta V x Conductance it is usually written as I = delta V/Resistance or more commonly V/R.

Since conductances add when in parallel; inverses of resistance add in parallel
Rpar =1/(1/R1+1/R2). Since inverses of conductances add when in series; resistances add in series
R series = R1+R2.

Circuit problems are solved by finding equivalent resistances or conductances for the combined elements in the circuit. It is easiest to think of adding parallel conductances to get the equivalent conductances for those elements in parallel. Then take the inverse of those conductances and add to the other elements in series with them.

AP Capacitors in Circuits

Capacitors or any other elements in a circuit only see the full circuit voltage across themselves if each end is connected directly to the a side Different side for each end, of course) of the voltage source ( say a battery). If there is some other element between it and the voltage source on either end, then the voltage is split between the two or more elements and the respective partial voltages depend on the characteristics of the elements. For example two 10 uF capacitors in series will each have half the total voltage across them. A 1 uF in series with a 4 uF will have 4/5 of the total voltage across it, and the 4uF will have the remaining 1/5 of the voltage.

AP Currents Schedule (Unit 12)

Here it is. A lot of work in a short time. Next week will be similar. Then a slower week and then another sprint up to break.

http://h1.ripway.com/DrCherdack/AP%20Unit%2012Currents%20Sched10.doc

http://h1.ripway.com/DrCherdack/Unit12ProblemSheet.doc

http://h1.ripway.com/DrCherdack/Unit%2012%20Worksheet%201r1.doc

http://h1.ripway.com/DrCherdack/Unit12Worksheet2kirchhoff.doc

AP Field Lab

For your reports provide a purpose and a brief description of what you did to a) develop the point data; b) draw the equipotential lines, and c)draw the field lines. Use coherent adult length sentences. Make the drawings reasonably neatly.

Retake: information sheets

Bring in your equation and info sheets, same as for the original exams. Two hours starting at 2:45 or so.

Honors retake

Here is a brief list/summary of topics for the exam retake. It is very similar to the original. Stay tuned for possible updates to this list. Last 2 review session Tu and Thu PM.

http://h1.ripway.com/DrCherdack/Retake%20topics.doc

Derivation of sorts for PE =constant x 1/r

Here is a sort of pre calculus derivation of why with a force that is proportional to 1/ r squared the potential energy goes as 1/r:

http://h1.ripway.com/DrCherdack/Potential%20Energy%20for%20Gravity%20and%20Other%20Forces%20with%20F.doc

AP Thermo

AP students, particularly those taking retest, should look these over

http://h1.ripway.com/DrCherdack/Thermonotes-prob-basic%20.doc

AP Unit on Electric Potential

Here is the new Schedule


http://h1.ripway.com/DrCherdack/APUnit11EPotSched%2010.doc

http://h1.ripway.com/DrCherdack/Unit11Worksheet1.doc

http://h1.ripway.com/DrCherdack/Unit11worksheet2onCapacitors.doc

http://h1.ripway.com/DrCherdack/Notes%20on%20Currents.doc

Honors Unit on Thermodynamics Schedule Etc.

Here is the schedule for the new unit on Thermodynamics. Be sure to do all the readings or I'll have to resort to surprise quizzes. Read the notes on heat before doing the schedule assignment. Read both the notes on Thermo and thermo notes where the schedule says read Notes on Thermo. Make sure you bring the Thermo notes with you to school all through March.

http://h1.ripway.com/DrCherdack/Notes%20on%20Heat%20R3.doc

http://h1.ripway.com/DrCherdack/HonUnit10Thermo-10.doc

http://h1.ripway.com/DrCherdack/Gas%20and%20Plasma%20Problems%20%20.doc

http://h1.ripway.com/DrCherdack/NotesonKineticMoleculaR1.doc

http://h1.ripway.com/DrCherdack/Notes%20on%20FluidDynamic%203-10.doc

http://h1.ripway.com/DrCherdack/Heat%20and%20Energy%20Conversionr2.doc

http://h1.ripway.com/DrCherdack/NotesonThermoR6.doc

http://h1.ripway.com/DrCherdack/Thermonotes-prob-basic%20.doc

Honors problem

Due to HSPAs we didn't get to drift currents yet so you cannot do Practice #5 yet. Tomorrow will probably be spent on final pretest review so we'll do it Monday.

For tonight's homework identify any Unit 9 homework problem you could not do. Try it again and email me if you still can't get it.

AP and Honors Tests

Despite my enormous influence in Trenton my request for the cancellation of Thursday's HSPAs was ignored. Since I can't even count on you clowns even getting into your seats in 20 minutes let alone complete a quiz, the tests will be on Friday, but I'll make them twice as hard for spite.

Honors Magnetics Test.

Please return your tests of 2/12. I need to correct the grades on some of them