Grades

1) For Honors and AP, your quarter grade is the last entry in test and Quiz category. It is right next to your exam grade. At least I think it is, but since i can see your HAC I can't be sure.

2) For research, come see me if you want a pre report card preview

3) For AP only I updated the three categories to correct typos and to include latest stuff turned in. I did not update the honors grades since you saw a printout from my grade book on Friday. There have been changes to a couple of things since then but the bottom line is that quarter grade discussed above.

AP Oscillaltions

1) The total energy in an oscillator is the maximum PE (k xmax^2/2) [which occurs when x =+or-xmax] or the max KE which occurs as the oscillating mass passes through the equilibrium point (Mveq^2/2). These numbers are the same.

2) What makes a harmonic oscillator harmonic is the fact that the restoring force ( the force pulling the mass back to the equilibrium position) is proportional to the distance from the equilibrium, i.e. the displacement; so F=-k x. Then if this is true the acceleration toward the center is k x/m.

For the x direction of circular motion, the acceleration = omega^2 x and if we set this acceleration= kx/m we can use the x component of the circular motion equations as long as we set omega ^2 = the same constant i.e. omega ^2 = k/m or omega ^2 = (Frestoring/x)/m. Monday, I am hoping to show you that the same equation holds for a pendulum, as long as it swings through a small angle.

AP Unit 9 Worksheet 1

In case you got yhe wrong link earlier, it is now corrected, ut here it is again anyway

http://h1.ripway.com/DrCherdack/unit9worksheet1r1RNC.doc

AP Oscillations and Waves Sched

Here is your new schedule and materials. Note the wave speed notes are the last 2 links ALSO Read the notes on Waves through page 9 by Thursday regardless of schedule.

http://h1.ripway.com/DrCherdack/APUnit9OscWavessch10.doc
http://h1.ripway.com/DrCherdack/Notes%20on%20Waves4-09.doc
http://h1.ripway.com/DrCherdack/unit9problemsheetr1.doc

http://h1.ripway.com/DrCherdack/unit9worksheet1r1RNC.doc
http://h1.ripway.com/DrCherdack/unit9worksheet2.doc

http://h1.ripway.com/DrCherdack/MaterialPropertiesandLongr1.doc
http://h1.ripway.com/DrCherdack/NotesonTransverseWaveSpeedR1.doc

Jackets

There are three black jackets in 506 that weren't there a few weeks ago. Claim them or they will go to the main lost and found.

Honors Section 2

I have three review packages that I could not enter because they had no names. Let's take care of this tomorrow.

Mid Year Exam Grades

I posted unofficial exam grades , I still need to check a few on some, on HAC in the test and quiz category.

Honors Assignment

Reread Nuclear reactions rates ( Notes posted on 12/22/09) and do the problems once more. You seem to have forgotten most of this.

AP Harmonic Motion Assignment

Read and understand these notes and the lab. We may get to the lab tomorrow, be prepared. Read Homework and do 1 and 2.

http://h1.ripway.com/DrCherdack/NotesonCircHarmonic2-09.doc

http://h1.ripway.com/DrCherdack/Simple%20Harmonic%20Motion%20Lab-09.doc

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

AP AND Honors

1) Group reports get em in. See yesterday's post of a spreadsheet for each class, press the tab for your class.

2) Get your midyear review homeworks in. They are worth six assignments

Honors Mid Year Updated Defs and Eqns and answers

Please bring these definitions and equations you down loaded for use on the exam.

No additional information can be added to them ( i.e. not notes on them.)

The Part B corrections were posted earlier. I will post all this on my OnCourse website as well

http://h1.ripway.com/DrCherdack/midyr%20DefsEqns-09-10.doc

Group Reports Are REQUIRED

Group reports are required for each unit. I should have 6 for APs (two for energy) and 4 for Honors (two for unit 5 since we covered it with two assessments, really 3). I will take 5 for AP and 3 for Honors but they must be in by Thursday!! , I'll take em by email. Again full page: who, when (date), subject topic not just problem sheet,and where

Here is what my records show, which is sketchy because of the very poor descriptions of what and when in many of your reports. ["Study hall reviewed problems" doesn't tell me much.]

http://h1.ripway.com/DrCherdack/Grades%201-25-10Grp%20Rprts.xls

Revised Part B Solutions

Here are corrected solutions


http://h1.ripway.com/DrCherdack/HnrMidyrAddlslns09-10r1.xls

PART B Corrections Problems 10 and 18

All the answers to Part B Problem 10 need to be multiplied by 10. [For complete corrected Part B solutions see later post of 1/25]

(a) 400 N (b) 400N (c) 560 N [Mg +Ma] (d) 480 N ( a is upward F >Mg) (e) 320 N ( a is downward F < Mg) (f) 520 N (a is upward).

Problem 18 (a) 9.67 E-5 kg mass of fuel in reactor at any time.

Honors Part B Solutions Corrections

Thanks to Miranda's diligence and intelligence we have identified thee errors in the solutions to Part B. I do apologize, but I did warn you that there were no guarantees due to the hour at which I posted these. [For complete corrected Part B solutions see later post of 1/25]

22) I forgot to divide by 2 when answering part A therefore the correct answers are:

vLi = -1/6 vp = -.5E6; KEi = 8.7E-15 KEf = 6.49E-13; He4 has 3/4 v of He 3 so it has 3/7 of total KE so He4=sqrt(3/7 x 2x6.49E-13/(6.68E-27)) = 9.1 E6 m/s

24) I changed the problem and then compared the solution to the old problem instead of the new one ( it was very late at night) so here are the corrected answers:

it should be T ends up with vTy' = 2E6 m/s in y direction so for (a)
vDy'= -3E6m/s; vDx' = -1.5E6 m/s

(b)DpTx = +1E6(5E-27)=+5E-21 pods DpTy =-1E-20 pods

(c)J= (sqrt(DpTxsqrd+DpTysqrd)= 1.12 E-20 pods so F = J/E-10 = 1.12E-10 N; r = sqrt( kQTQD/F) = 1.42 E-9 m

26) 20 keV = 3.2 x10^ -15J v=sqrt(2x3.2x10^ -15/5x10^-27)=1.13x10^6; vperp 2/3 x v ; Mvperp^2/r =QvB cancel one vperp so QB = Mvperp/r so B = Mvperp/Qr = 5E-27x 7.5E5/(1.6E-19 x .02) =1.17 T

Honors Centripetal Force Lab

Some major errors and misconceptions here.

1) Use 9.8 m/s^2 for labs

2) A few are still using the mass of the washers x ac even though it is the stopper and not the washers that are accelerating.

3) A few of you have totally confused yourselves. Pay attention to this.

The stopper is not in equilibrium: IT IS ACCELERATING! [ After all, you just told me what ac is and it sure was not zero.]

FTension does NOT CANCEL Fc; IT IS Fc! and we are trying to see if FTension from Mwashers x g does indeed equal the Fc from Mstopper omega squared r. Again, FTension doesn't cancel Fc; FTension is providing Fc.

Labs

Lab reports are coming in with identical spread sheets and near identical text. You have been warned before. Being told to get data does not entitle you to copy calculations or text. Labs with this level of duplication get zeroes for all but the original authors.

AP Labs

Many of you missed some important points in the power and specific heat labs.

1) Power labs: the major reason for the increase in power in shorter times is not the increase in KE which has a relatively small effect since the work is till dominated by delta PE. Rather it is the decrease in the denominator in P =(delta PE+delta KE)/delta t.

2) Purpose was to show how power is affected by change in delta KE, delta PE and most particularly delta t.

2) Specific heat lab

a) Largest source of error is in Tf-Tw since this was between 5 and 10 deg C and error in reading is about 1/2 a deg so errors here alone are between 5 and 20 %.

b) most got it right that purpose was to prove conservation of thermal energy, that Q out of hot = Q into cold and some of you even discussed how the energy was exchanged via collisions.
c) many of you still do not write explicit equations. Every lab should have had an equation such as cblock = (Mw cw delta Tw + Mcan ccan delta T can [same as delta Tw])/(Mblock delta T block)

d) some of you think all silvery metals in room 506 are aluminum. If your block had a mass much more than 88 g it was not aluminum. Zinc or steel would have masses more like 250 g. These metals have cs near 390 and would give you reasonably small errors.

Email AGAIN

Its down again. I'll try to get in touch when it goes back up. See some of you tomorrow.

AP Thermo Cycle Problem

The solution on the solution set is for the original values which somehow got garbled in the editing when I moved the figure . The original values were 200 kPa at A and B 20 kPa at C; 40 m3 at A 80 m3 at B and C. Now the cycle makes a bit more sense with the temperature at A being 962 K, and n being 1000 moles.

Honors Review Solutions

I think they are mostly right but no guarantees at 4:30 AM. The document is for Part A and the spreadsheet for Part B. If the links give you trouble you can get them from my OnCourse website - see homework for yesterday, that is Thursday. For corrected Part B solutions see post of 1/25

http://h1.ripway.com/DrCherdack/Midyrrev09-10hnrssln.doc

Extra Help

If you plan to come for extra help and to travel other than during the passing time between exams, get a pass from me.

Mid Year Exams: cell phones and luggage

Do not have a cell phone on your person when you are taking an exam. Place them in your backpacks, hand bags, leave em in your locker, whatever, but do not have them in a pocket etc.

All baggage etc. will be placed in the front or back of the room during exams.

Room 506

I am missing a TI 83 calculator with red paint across the top edge. Pleas return it.

There are two black jackets laying in the back of 506

Some money was found in 506 late last week. If its yours, let me know what the amount and denominations are and you can get it back.

AP and Honors Group Reports

Reports will not be credited if they do not identify Topic and Unit, DATE, Who, Where.

ALSO, THEY MUST BE ON FULL PAGES

AP Review Solutions

Here are the answers

http://h1.ripway.com/DrCherdack/APMidyrRev09-10%20sln.xls

Grades

I have posted grades in the usual 3 categories, Labs, Tests, and Homework. Once again, the overall grade HAC computes IS NOT YOUR ACTUAL GRADE. If you have any questions about your grade, email me or see me outside of class time. A few of you should have received emails from me about some items I am missing in my records.

AP Review Problem 31

The collision between gliders in problem 31 is totally elastic.

AP Thermo Test

Many of you are still trying to get by without understanding things. Q = mc deltaT doesn't do much good if you don't recognize it as the flow of thermal energy into a body. If thermal energy is conserved then for a closed system the heat into the colder elements of the system must = the heat OUT of the hotter elements. In other words its Q into the cooler = -Qinto the hotter or more clearly:

mc delta of the cooler = -mc delta T of the hotter elements.

That minus sign is all important and leaving it out shows you don't understand what the conserving of a quantity means. Many of you managed to take 75 or 85 degree water add it to 25 degree water and geta final temperature of over 100 degrees. This indicates a total lack of understanding of the meaning and behavior of thermal energy.

An easier way to find Tf for a system reaching equilibrium is to take all the Us ( mcTs), add them together and then divide by the total heat capacity ( the sum of the mc for each element). This may become too complicated when there are phase changes

Some of you suddenly introduced atmospheres as a unit of pressure with predictably disastrous results. You do not need a non-standard alternate system of units to add to your difficulties. No KMT or thermodynamic equations should be expressed in such an accidental unit.

AP and Honors

For AP, Midyr review: For Monday to question 11. For Tuesday to question 38, For Wednesday up to question 55 For Thursday complete the review sheet

For Honors Midyear Review: for Monday up to question 35 for Tuesday, complete part A( question 50) and do part B questions 1,2,3,5,6 remember E = m csquared for number 5. For Wednesday do Part B 8 through 21, Complete Part B for Thursday

Updated AP Midyr Review

Hot off the press. Do up to 35 by Tuesday class time. Its crunch time.

http://h1.ripway.com/DrCherdack/APImidyrRev09-10.doc

Honors Assignment Reminder

Do through question 35 on the review package

Honors Review

If the link for the review packages posted yesterday doesn't work, the review package was also posted on my OnCourse website under homework for yesterday (Thursday).

AP Midyear Review Material

Here is what we will use to prepare for the mid year exam. An updated version will probably appear soon. In the meantime do the first 11 problems by Monday. If the link doesn't work, this is also posted on my OnCourse website as homework for yesterday (Thursday).

http://h1.ripway.com/DrCherdack/APImidyrRev09-10.doc

Honors Review material for Mid year exam

The title says it all. Homework for tonight do first 10 questions, you can us the equation sheet since the equation sheet will be given to you for use in the exam.

If the link doesn't work, the review package was posted on my OnCourse website under homework for yesterday (Thursday)

http://h1.ripway.com/DrCherdack/midyr%20DefsEqns-08-9.doc

http://h1.ripway.com/DrCherdack/Midyrrev09-10hnrs.doc

AP Carnot cycle

Study for the quiz. Do the carnot cycle on Thursday night.

http://h1.ripway.com/DrCherdack/Cycle%20Carnot%201-09r1.doc

AP Test

The test will include thermal expansion, conservation of energy with changes in Temp ( M c delta T=Qin) mixing problems like dumping a hot block into cold water ( don't forget the container), heat transfer by conduction and radiation. kinetic molecular theory ( including m(v^2) avg/2 = 3/2 kT) and PV=nRT . Remember things like latent heat of fusion, Lf ( melting or freezing) and latent heat of vaporization LV ( evaporating or condensing).

APUnit 8 problem sheet

The answer to #14 is 34.4; some one forgot to multiply by the 20 m^2.

Honors Students

1) Quiz will be tomorrow and will cover

angular description of motion: delta theta, omega, vtan, delta s ( distance or displacement along the perimeter)
circular motion including centripetal force in magnetic fields (including finding v , omega, and r), circles in vertical direction ( like Feris Wheels and loops and hilly roads, and circular motion in a horizontal plane ( vertical forces don't matter)

2) For tonight find v, F ,r and omega for deuterium with 50 keV of kinetic energy in a magnetic field of 7 T AND vperp = 1/3 v ( i.e. only part of the velocity is perpendicular to the direction of the magnetic field, a typical condition in a tokamak.)

Absence

Sorry I've been out guys. You probably all realize that I would have been there if I could. All I can say about my sore back is that I hope none of you ever feel what I have felt for the past two days, not even my chatterboxes in the honors classes or EVEN the whiners in AP.

I hope to be back tomorrow. You should keep up with the homework; the notes and text should enable you to do that. In any case, the tests scheduled for Thursday will be adjusted in scope [ or possibly postponed - but I don't like this idea] to reflect the fact that you have not had the full benefit of my extraordinary teaching talent.

Honors Research just keep going.

I am shooting to return tomorrow, Wednesday, but it is up to a bunch off neurons behaving themselves. Hard to believe, but a kind of miss you folks.

Updated Honors Unit 7 Schedule

Here are your materials for our unit on circular motion and magnetic fields. There will probably be some additional problems posted here.( I posted last year's at first... this is the correct one)
http://h1.ripway.com/DrCherdack/HonorsUnit7Rotsch9-10.doc

http://h1.ripway.com/DrCherdack/circularmotionproblemsWSR4.doc

http://h1.ripway.com/DrCherdack/ProblemSheetR-1rev1.doc

http://h1.ripway.com/DrCherdack/NotesonTorquerev12-30.doc

Honors Assignment

1) Find the radius for a tritium nucleus moving with a v perp of 6 x10^6 m/s in a magnetic field of B = 6 Tesla.

Note w = omega in what follows.

2) Given that mw^2r=qwrB write an expression for w in terms of qB and m and then find w for an electron, for a deuterium and for a helium 4 nucleus, all in a B=4T magnetic field.

3) Given that B = u0 I/(2 pi r), where u0 = 4 pi x10^-7. How much current, I, must a wire carry to produce a 4 T field 2 m away from the wire?

Specific heat lab

Lab sheets for this lab are in the outfolders, and I'll postpone the due date until Firday for Section 1.

Note that there is an error in the equation on the bottom of page 84 ( second page). it should be (Mw x cw x deltaTw) +(Mcontainer x ccontainer x deltaTcontainer)

delta T container does =delta T water

Honors Assignments on Rotational Motion, etc.

Read the definitions etc. and then really read the definitions etc. and then really read the definitions etc. and then read the notes on motion in magnetic fields twice and then reread the magnetic field notes posted on New Years eve, and then do 1 and 4 on Sheet R3A.

Note thatI have clarified the post on sigma v from yesterday so read that again.

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

http://h1.ripway.com/DrCherdack/Rotational%20Motion%20in%20Magn.doc

http://h1.ripway.com/DrCherdack/Problem%20Sheet%20R-3A.doc

AP Thermo Package

Someone printed out the AP Thermo package and left in a printer. These things show up in my mailbox once in a while, so if you are looking for it I've got it.

Break Package Solutions

You should have your break packages back, but in any case here are solutions:

http://h1.ripway.com/DrCherdack/AddlMechRevQuest08-9sln.doc

http://h1.ripway.com/DrCherdack/Free%20Resp%20solns%20breakpkg.pdf

All Students English Cliff notes

Someone left English Cliff Notes in room 506. If they are yours contact Sean Halverson.

Honors 2 Folders

1) Half the incoming homeworks were placed in the out folder rather than the in folder. Please be more careful.

2) Many of you left graded labs etc. in the out folder. This is stuff that I took time to grade during the break. It makes me feel my efforts are really worthwhile, right?

Honors Reaction Rates

The graph in your notes present the sigma v as a function of temperature in KeV. Unfortunately they label the "sigma v" as "reaction rates". It would be the reaction rate if n = n2 =1 but it is not the reaction rate in our cases with our much, much higher n s.

It is a log log graph so it can show and enormous range of information. Each little tick is an increase of 1 x the quantity listed below the tick. In other words the first tick above 10^-22 means the sigma v is 2 x10^-22. At 20 KeV ( one tick to the right of 10 KeV, the sigma v is about 7x10^-22.

Hope this helps.

AP Unit 8 Thermodynamics

Here are the multiple links for thermo.

Although they are missing from the schedule, read the notes on Kinetic Molecular theory, Preferably Monday night but no later than Tyesday night.

Also, some more text work amy be assigned so stay tuned.
http://h1.ripway.com/DrCherdack/APUnit8Thersched09-10.doc

http://h1.ripway.com/DrCherdack/Notes%20on%20Heat%20R3.doc
http://h1.ripway.com/DrCherdack/NotesonThermoR6.doc
http://h1.ripway.com/DrCherdack/NotesonKineticMoleculaR1.doc

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

Power Lab

Apparently some of you misunderstodd the power lab we did on Wednesday. It was not a makework time filler. You are to complete a report on it with data and discussing how you found work done (considering both the change in KE and in PE) and average power developed . You should compare the power generated at low and high speeds and with and without the backpack. The information you need was provided by the measurement of the height, the distance, the times. You also need the runner's mass and the backpack's mass (pick up the phone and call them if you need to). Remember 1 kg has a weight 2.205 pounds. You should also find the power in horsepower (hp). 1 hp = about 746 watts.


I'll be a softie, lets make it due Tuesday. [Honors Sect 2: we'll do the lab this week so the due date will be different for you]

AP Tests

AP should prepare for a test on mechanics ( everything so far but fluids) for Thursday. A schedule for our new topic, thermodynamics will be posted soon.

Grades

Your grades are posted. Most of the low lab grades are because see me s and resubmits are now scored as zeroes. This should get you to resolve them quickly. Any resubmit or see me must be resolved within 6 school days.