AP Momentum Lab

I would like to tie in the momentum lab with enrgy conservation during collisions. I had asked you find out how much KE was lost during the collisions. This takes writing about five equations and copying them for each run. I would like you to identify which runs had the greatest losses and see if you can explain why. Do this with a paragraph or two citing percent differences and characteristics e.g. both carts moving , lots of bars, or whatever is appropriate. Bring it in tomorrow.

Thanksgiving

One good way to give thanks is to help others, so put those cans next to your book bag now. This way you won't forget them on Monday. Oops, shouldn't mention Monday on a holiday weekend.

AP Ballistic Pendulum Lab

We did not complete the lab with the ballistic pendulum yet. We just found vsphere, but we haven't checked it yet. We will complete it Monday or tuesday and the lab will be due the second day after that.

AP and Honors

Just a reminder, work = F x displacement in direction of force. For most cases we deal with work = area under force vs displacement graph. More accurately, work is the area between the force curve and the F=0 axis because work is negative when force is in opposite direction of displacement which would show up as a curve under the F= 0 axis.

AP Retest

A retest will be available for all those who got a raw score of below 85 on the momentum test. It must be taken on Monday and you must let me know by email before Monday if you want to take it.

Thanksgiving

During this Thanksgiving break take a good look around you. I hope you see lots to be thankful for.

Take some time out to say thank you for all the good things. Say it quietly, inside where you feel it, and say out loud to those who should hear it from you.

While I am reminding people to be thankful, I will say thank you to you folks for trying to learn.

Grade Changes

I have put in some grade changes you might want to look at. In honor of the holiday I refrained from all those major reductions in grades I had planned on and I did raise a few.

Rockets Again!

Here is the link to the better but not great rocket data and calcs. I understand off course is off the rails once again.

http://h1.ripway.com/DrCherdack/Katelyn%20SrcktcalcR1.xls

Honors, AP and Topics

Now is the chance to show people that you are not all self centered, grade grubbing, egotistical, megalomaniacs. Now you can show people that you are caring, kindhearted, and supremely charitable to the less fortunate around you. In other words now is the time fool everybody. BRING IN THOSE CANS.

Calculators

Please check to make sure you are carrying around your own calculator as 506 students are missing a few. I know someone has David Shang's for instance. Please return them to the prpoer owner or me ASAP.

Opportunity in April

I received this from Ms. Van Der Stad, a 4th grade teacher at Oak Street. Please let me know ASAP if you are interested. We would start planning in march. Could be fun to build our own and see if we can beat 4th graders, oops, I mean assist 4 th graders. Also could be a nice way to wind down from the Jnauary physics olympics.

Thanks so much for being excited about an opportunity at Oak Street! We have four 4th grade classrooms. Basically, we are looking for two groups of 4 students (8) to come down to Oak Street (for a 2 hr. block) and do some sort of experiment and/or discuss the concepts of Motion and Design. Each group of 4 students would present the same information in two classrooms.

We will be starting this unit probably in April. So, any time during that month would be wonderful.
In the 4th grade Motion and Design Unit, students work with Kinnex to create cars. With the cars they do different tests to see how the change of shape or addition of other materials (sail, fan, thicker rubber band) change the speed of the car.
If any h.s. students would be willing to come down, our students would love it!

Any ideas of what the h.s. students could talk about/ show them would be great.

AP Section 1 Momentum lab Spreadsheet

I checked the file I tried to upload.It has values not equations. Apparently when our network uploaded the file it went to an earlier version saved somewhere on our servers. This also happens once in a while when I print something.

Revised Rocket Lab

Sorry guys but there was an error in the last spread sheet for the rocket lab. Here is a revised copy. The data is faulty and our assumption about a being constant during the burn is also faulty. The rocket acclerates more at first so it actually reaches close to vf soon after launch.This means that vf is closer to vavg. However, that's one thing a lab does. It let's us know where our assumptions are out line. Using ttop - tbo gives a height based on vbo. The column other gives a height based on vbo squared. Thus the discrepancy between the two Htop- hbo columns shows our vbos are probably too high.This explains our impulses and heights being higher than expected.

My best guess about the data is that for the first run someone forgot that hbo was measured from 2 m from the pole so hbo is the cm sighted on the meter stick x 30 (/ 100 to get m) not x60 . Lets say that the first hbo is thus 1/2 as great. Lets see what happens when we divide this hbo by 2. see row 17 on the spreadsheet. We get poor, but not incredibly bad, agreement. Other possibility is that hbo was confused with htop. In any case here its ( well soon, still can't upload from here). I will post it as tonight's homework on Off course.

Publish Post

Honors Ballistic Pendulum Lab

This lab is formal because it needs a procedure otherwise who will know what you did? Discussion should include the calculations you made to find v' ( right after the collision of the sphere with the catcher) from the PE final which equaled the KE right after the collision and then how you used conservation of momentum during a collision and the ratio of m' the (total catcher + sphere mass) to the sphere mass to find v sphere before it hit the catcher. Note that the effective mass of the catcher was 116 g so m' = 116 g + mass of sphere. There should be references to conservation of energy ( how you found KE from PE) and conservation of momentum ( how you found v from v'). Note you cannot say you proved anything since we have not measured v sphere to see if your calculated value for v sphere was correct. You can conclude something about how you can use conservation laws to find things out.

Section 2 lab is due Tuesday but I'll give an extra day since the rocket lab was so tough. Section 1 is still due Wednesday.

Rocket lab

As of this time, the only nearly complete set of data I received was from Katelyn Stover and her group, Kevin and Armon. I took their data and enhanced it a bit and calculated Js and free flight heights. The equations I used are in the cells. Take all this and create a report showing that you understand the calculations and repeating them in your reports. Add a sample problem where you specify mass and rocket engine J and burn time and calculate v bo Hbo and H free flight ( Htop - Hbo). Lab will be accepted until Wednesday end of school.

http://h1.ripway.com/DrCherdack/Katelyn%20Srcktcalcs.xls

AP Energy and Work Unit Schedule

Here are the goodies. Also try reading the notes on energy fundamentals tonight and reread the notes on torque when we get to rotational energy.

http://h1.ripway.com/DrCherdack/AP%20unit%206%20Energysched-09-10.doc

http://h1.ripway.com/DrCherdack/Notes%20%20Work%20and%20Energy%20R5.doc

http://h1.ripway.com/DrCherdack/NotesEnergyFundament9-09.doc

http://h1.ripway.com/DrCherdack/Unit6%2009-10Work%20ws1.doc

http://h1.ripway.com/DrCherdack/Unit6%2009-10WS2.doc

http://h1.ripway.com/DrCherdack/unit6-09-10EnergyProbSht.doc

David Shang

Are you in possesion of someone else's calculator? If so please email me.

Momentum Spreadsheets

each group for all classes should have sent me a spreadsheet with formulas in the v, p, etc cells. Only the mass and time cells should have simply numbers. I am still missing a few ( about 5 of 24)

Honors Project Reports

By Monday each group should turn in one project proggress report on what you have accomplished since 11/11.

Study Group reports

Unit 5 study group reports should be in for all AP and it would be a good idea for honors as well.

Honors Assignment

Las night's assignment should have been Chapt 7 not 5 . Sorry. Do the Chapt 7 work for Monday. Focus on getting good rocket data tonight.

Topics in Physics

An oldie but a goodie so please review this if you were in my AP or read the first 8 pages tomorrow
http://h1.ripway.com/DrCherdack/NotesonSpecialrel15A.doc

AP Sect 1 Momentum Lab

I found the error leading to the 800% error. The time was missing a zero after the decimal point. There are still at least two suspect pieces of data and these are noted on the spread sheet with red colored cells and comments below. One I am pretty sure of the other, I don't really know.

I tried to load the file onto to my usual server, but I can't do it from school sites detect viruses when I try to connect???) so I'll load it at home and send you the link then. in the mean time I'll try to put it on offcourse ( my school website) as yesterday's homework

Calculators

I would like to thank the two generous students who have contributed their calculators to the room 506 inventory. In the unlikely event that you choose to renege on these gifts, please see me. and [ I am adding this at the request of a student] I love BROWNIES!!

AP Test

You are not responsible for angular momentum. In fact as far as I know, the only thing you are really responsible for is making a mess in my room and keeping here to all hours. However responsible or not, angular momentum won't be on the test.

You are also not expected to know anything about KE, or much else for that matter, but at least KE won't be on the test.

AP Chapt 9 prob 61

Use kinematic equation Dy = (vyf^2-vyi^2)/2a to find vyi immediately after explosion. Note that of this vyi 20 m/s was due to pre explosion velocity so delta v due to explosion = vyi-20m/s = 80m/s.

impulse upward from explosion on lighter fragement = impulse downward on heavier fragment

Since other fragment was twice as massive its Dv due to the explosion is 1/2 as great so it's v right after explosion = 20 m/s( the pre-explosion v) -80/2 = -20 m/s

Honors homework help

for problem 1 note v1 ' = - 1.8 m/s and then use conservation of momentum to find v2' = 6.77 m/s. Then find KE -KE' suing v1 for initial KE and v1' and v2' to find KE'. KE' = Ke1' + Ke2' obviously.

problem 2 use the equation for v' for elastic collsions at end of unit schedule to v1' and v2'. Use KE2' goes to PE spring where PE spring = k/2 change in length squared.

Rocket lab due date

Rocket labs will be due Friday. Make preliminary calculations by Thursday so we can see which of the data is any good.They are informal. However you must show how you calculate the J of the rocket motor and see is the difference between h burnout and h top is consistent with the vburn out and free flight after burn out.

remember that gravity is supplying a negative impulse during the burn phase

you can use the vburn out to find the time from burnout to top of flight. see if this consistent with your measurements. You can use v burn out and vtop = 0 to find the average velocity during free flight and use this and time of free flight [ t top - tburn out] to see if htop- hburnout = expected delta h for free flight.

Make it interesting and informative, and make it right.

Canned Food

BRING IT !

After Collision

The prime or apostrophe ' means after the collision.

Rocket labs engine masses

Rocket masses are without engines and the engine masses are : B6-4 19 g; C6-[C6-3 or 5] 24 g; A8-3 16 g.

AP Homework help

1) extra problem sheet #11 ( apologies to Neel)

An 80 kg skater and a 40 kg skater face each other on slippery ice. Without digging in ( i.e. no friction) they push of each other. If the 80 kg skater has a velocity of 3 m/s north what is the 40 kg skater’s velocity?. If the 80 kg skater digs his skates in and pushes horizontally against the ice with a force of 100 to the north for 1.0 seconds while the second skater pushes against him exactly as she did in part (a) what will the 80 skater’s velocity be?

a) 40 kg skater has equla but opposite p so has a v= 6 m/s south

b) impulse from skater A on B = p' from part a= 80 x 3 north now the ice provides a J of 100N x 1 sec to the south so total J on B = 240 north =100 south = 140 pods north so v' in case b = 140/80 m/s = 1.75 m/s north

Honors Homework Help

I wnet through a couple of dozen homeworks from the last week or so.

General comments:

Chapter 16 #41 was done in class

Many of you don't recognize the nature of a problem yet. For example, Chapt 16 problems 44,45, wer Gauss Law problems and should be approached accordingly.

Some of you still think a cm is a meter. If I lend you a penny will you pay me back a dollar? Well cm vs m are the same thing pennies vs dollars a factor of 1/100.

Details:

Honors HW help 11/2 through 11/16
Miscellaneous errors some of you did QT + QS instead of QTxQS in the equation for force between charges

many of you still do not distinguish between cm and meters 1 m squared = 10,000 cm squared so this mistake makes your answers come out very wrong!


Giancoli Chapt 16

# 44 flux = field passing through area = 580 x pi x.18^2 when field is perpendicular to area and flux = 0 when field is parallel to area surface , no field passes through

#45 Use Gauss Law flux = 4 pi Qtotal enclosed
so flux for A1 = 1.13x10^11 x( -1x10^-6 –2x10^-6)

flux =0 for A2

Giancoli Ch 17 [D = delta here ]


Question 5: a point exactly in the middle between two equal positive charges will have zero field since the field from each charge will cancel the other here and only here. The potential is nowhere zero since work would have to be done to bring a positive charge from far away to anywhere near these charges. The zero field point is surrounded by outward pointing fields that you would have to work against to bring a positive charge into this point.

problem #21
DKE = -DPE
when they are very far away from each other PE = 0 KE i = 0 here so KEf = PEi
Mass = 1 mg = 10^-6kg
PEi = kxQsxQT/r = 9x10^9 x 9.5x10^-6 x 9.5x10^-6/ .035

so KEf = 9x10^9 x 9.5x10^-6 x 9.5x10^-6/ .035 = 2.32X10^1 J
v = sqrt( 2KE/Mass) = sqrt (23/10^-6) = 4800 m/s

#70

Ignore capacitance
DV = 35x10^6 Dx = 1500m, so

E = DV/Dx = 23,700 V/m from Gauss: E Area = 4 pi k Qs = 1.13 x10 ^11 xQs

so Qs = E Area /1.13 x10 ^11

Area = 110sq km x10^6 sq m per sq km = 1.11x10^8 m^2

so Qs = 23,700 x1.11x10^8/1.13x10^11 = about 23 Coulombs

Gauss’ Law #2
Flux = E x area = 4 pi kc xQ enclosed by flux surface so Qenclosed = flux/(4 pi x9x10^9) Flux = surface area of box x (-)450 V/meter = [ 2 faces x .2x.2 + 4 faces .4 x.2] = .4 m2 x (-)450 = 180 Q = 180/1.13x10^-11 = 1.59 x10^-9 Coulombs

Giancoli Chapt 7

#7 total p before = total p after

12600 kg car moving at 18 m/s has p (in the horizontal direction) of 12600x18 =226800 pods gravel has no horizontal momentum so p total = 226800 and after the collision the loaded car has a mass of 17950 kg and still a momentum of 226800 so v’ = 226800/mass = 226800/17950= 12.6 m/s

Honors Sect 1 Lab data

Here is the link to your data. See Saturday's post to see what to do with it.

http://h1.ripway.com/DrCherdack/Momentumval%20hnr1.xls

Nick Mak

Please check your email. I sent an important note to you

Honors Project Assignment for Tuesday

Each group has to turn in one summary of what they hope to accomplish on Wednesday during their project group meeting. It should cover how you are to make progress designing your system. Maybe its understand an equation or two, maybe its how to find one of your design quantities

Honors Sect 2 and a few from Section 1

Study Group Reports see blog for October 14. Section 2 must turn them in by this Thursday

All Students

Two items

1) Food Drive begins Wednesday, bring in canned food

2) Anyone interested in an engineering or science program over the summer, here's an announcement from Vanderbilt.

PAVE is a six-week summer course of study designed to strengthen the academic skills of students who are planning to enter a college engineering, pre-medical, science, or technology program. If you are an eleventh grader and planning to take advanced placement or honors mathematics and science courses, the pre-college PAVE program will fortify your senior year and potentially improve your ACT, AP, SAT and TOEFL test scores while increasing your chances for admission when you apply to college. If you are a graduating high school student and are planning to attend any institution, this program not only exposes you to campus life, but also provides you with the experience to overcome the rough spots you may encounter. For more info go to https://pave.vanderbilt.edu/ayindex.php

Email Down Again

Sorry guys, but email is down again so I can't hear you. I'll keep you posted.

Honors PMomentum ( Unit 5) Schedule

Here are your schedule and links for pMomentum in 1 dimension.

http://h1.ripway.com/DrCherdack/HonUnit5-1DMomSched09-10.doc

http://h1.ripway.com/DrCherdack/Unit5Worksheet1r1.doc

http://h1.ripway.com/DrCherdack/Unit5Worksheet2r1.doc

http://h1.ripway.com/DrCherdack/Unit5ProblemSheet.doc

http://h1.ripway.com/DrCherdack/Unit5extraproblemsr1.doc

http://h1.ripway.com/DrCherdack/Collision%20Worksheet%201.doc

http://h1.ripway.com/DrCherdack/Collision%20Worksheet2r1.doc

AP Sect 2 and Honors Sect 2 Lab Data

Here are links to lab data. Note that I have done all the calculations for Honors. AP calculations were done by the students but they still have to calulate percent errors. Note that in many cases percent error is similar for p before = p after and Delta p Wanda = -Detla p Dora, but for both carts having an initial velocity the delta p error is much more reflective of the accuracy of the trial.

Your job is to figure out all the equations used in each column after tb2 and write them out in your lab discussion. Your report is a formal one including error analysis and GOOD conclusions. In addtion, each group must email one spreadsheet to me with the values repaced by the formuale you figured out for the cells after tb2. Because of the extra work, the lab is due Thursday. I expect each group to meet before then.

Gate a is the window gate, gate b is the door side gate. Note that if Wanda is more massive than Dora then Wanda will go through gate b after the collision. If Dora is more massive than Wanda then Wanda should go back through gate a and her velocity' will be negative. In fact any nonzero ta2 reading from gate a will represent a negative v' for Wanda. Wanda may also go back if Dora is about as massive and is moving before the collision.

Also note that if ( and only if) Dora is moving before the collision .025 /tb1 gives her velocity and it is NEGATIVE! and tb2 will give v' for Dora and it is positive.

Also note if you are going to use a cell in a calculation it must be a number only, NO LETTERS.

AP:http://h1.ripway.com/DrCherdack/Momentumvalssect2.xls

Honors: http://h1.ripway.com/DrCherdack/Momentumvalshonsct2.xls

Honors and AP Momentum

Both Honors and AP should read this document and do the sample problems for Mnday

http://h1.ripway.com/DrCherdack/Notes%20on%20MomentumRev1.doc

Honors Assignment

Read Chapter 7 Sections 1,2, and 3. Answer question 1 and think about question 2. Do problems 1,3 and 7

AP Section 2

The scales are still out. What does it take guys?

Honors Assignment

Honors Physics Gauss’ Law Assignment

1. In a neutral beam injector a voltage difference of 500,000 V is created across a gap of .25 m between two large metal plates.

a) What is the field?

b) Assuming that the field is created by a layer of positive charge on a metal plate at one end of the .25m and a layer of negative charge on a similar plate at the other end, how much charge per square meter of plate is required to provide this field?

c) if the injector is designed to accelerate negative deuterium ions (deuterium nuclei being orbited by 2 electrons instead of the usual one) to the right, on which side is the plate with the positive charge?

2. A rectangular box .4 m high and .2 m wide and long has an average field of -450 V/m passing through it surfaces. How much (net) charge does it contain?

Physics/Science League

The schedule for the physics/science league team run by Mr. Gilmore is posted on the fornt baord near the hall door. If you like puzzles and problems, give the league a try.

Centripetal Force Lab

Several of you are making very sloppy assertions about the absence of net force in this lab. There is a net force on the stopper. It is accelerating. The net force is the horizontal component of FT.

There is no net force on the washers. At the washers FT = Mwashers g.

Honors Fusion Power Report

Here is the link AGAIN

http://www.ipp.mpg.de/ippcms/eng/presse/pi/02_06_pi.html

AP 2 lab cleanup

I found five scales out after your clean up efforts and 2 sets of brass weights. I also found weights all over the room and one ramp was carelessly balanced on a box instead of replaced on the rack. In addition, equipment is still being damaged. Therefore all of you who were not still working on the lab after class today have earned -15 points on the torque lab to start with.

We can stop doing labs and just adjust your grades downward by 17 to 20 points or you can learn to care for equipment.

Honors Assignment

Tomorrow is a group research day. Make sure you can use 40 minutes productively. Know enough to start work. Bring in downloads, articles, or books if you need to. Do the following tonight and write a couple of paragraphs about what you learned

1) Plasma group read the two pages on plasma in your text and read the portions that discuss plasma in the European fusion power plant report.
2) heating group go to ITER.org and print out and read the neutral beam injector writeups.
3) magnets read magnetics sections in your text
4) blanket and first wall read about thermal ( heat) conduction in your text and print out and read any blanket sections in European fusion power plant report.
5) thermo group read about thermal ( heat) conduction and thermodynamics in your text
6) electric generators ( dynamos) read about magnetics and Faraday induction in your text

All students: Canned Food Drive

Canned food is being collected in all first period class rooms. These means my AP 1 and topics classes. Other classes: if your first period room is not collecting bring the food to 506.

Show the world you care about other people, bring in plenty of food starting Wednesday Nov 18.

Honors Assignment

Your assignment is as follows,

1) make sure you can do everything on the last test really well ( no peeking if you haven't taken it yet)

2) Do all the flux problems assigned up to now.

3) use a spreadsheet program to prepare a data table for the 50 gram run on your a=F/m lab. If you are in section1, make a scatter chart of a vs 1/mass for the 50 g run and use the linear trendline to find your slope. Make sure you select the display equation option from the trendline dialog box. Compare the slope which = M a with the .49 N force on the system.

AP Labs

Two items Centripetal and Torque Labs

1) Centripetal force lab (5 sub items):

A) friction doesn't change the time reading or speed directly. It does affect what is going on in three possible ways. (1) friction between the string and the top of the tube can reduce the tension at the stopper since now the friction is "absorbing" some of the tension produced by the weight of the washers. (2) A tape rubbing on the top of the tube can produce the aforementioned affect in spades. (3) tape rubbing on the bottom edge of the tube will allow tension in the string above the tape to be higher since some of this tension will be "absorbed" by the friction before reaching the washers to hold them up; i.e. tension at washers is lower than at stopper. Effects 1 and 2 will cause Ms x ac to be lower than Mw x g . Effect 3 will cause the reverse.

B) Measuring radii incorrectly, letting washers swing or orbit, and miscounting rotations are also important sources of error, but can be nearly eliminated by using reasonable care.

C) Since we measure L not r, the vertical component of the string is not important directly. Since r = L cos theta horiz and FT horiz is FT cos theta horiz

FT = Ms omega^2 L cos theta horiz/cos theta horiz = Ms omega^2 L. The real reason for a near horizontal orbit is to reduce the importance of friction vis a vis the other forces by minimizing ratio of normal force between string and top of tube to tension.

D) Some of you have mentioned that Fg is zero. This very very wrong. I assume you meant Fnet on the washers is zero so Ft = Fg on the washers, but this error is so important it still calls for a rewrite. Also note Fg on the stopper in never zero so the tension on the stopper MUST have a vertical component! so that Fnet vertical on the stopper is zero.

E) Fnet on this system as whole is not zero. Part of the system is accelerating with respect to the system, but also with respect to the outside environment. Your hand holding the tube is supplying a net force on the system in the direction of the ac. Think about it. The string is pulling on the tube in the horizontal direction. You are providing a force opposing this. You, in effect are providing the centripetal force. (You are also holding the tube up allowing it to provide the vertical forces canceling the Fgs on the washers and the stopper, yielding no net vertical force on the system.)

2) Torque lab is just fill in but make sure you answer the last question even though it is marked Optional. Also with regard to the questions, we do not use triple beam balances in 506. They are convenient but not trustworthy, not durable. However, most of you still know how they work so answer the question if you can. Lab is due Tuesday.

Email

Email came back on line this afternoon

AP and Email

1) The Bernards BOE Email is still down so I can't "hear" you

2) Here is the Unit 5 Momentum schedule for AP

http://h1.ripway.com/DrCherdack/APUnit5MomntumSched09-10.doc

http://h1.ripway.com/DrCherdack/Unit5Worksheet2r1.doc

http://h1.ripway.com/DrCherdack/Unit5extraproblemsr1.doc

http://h1.ripway.com/DrCherdack/Unit5ProblemSheet.doc

AP and Honors Missing or resubmit Lab update

Two items

1) Here is the latest on labs either missing or requiring correction and resubmission

AP 1: Evan, got your parallel and perpendicular components lab and you did very well on it.

Jay very good work on centripetal force.

Four people still owe centripetal force labs

AP 2: Brian good work on resubmission of components

one centripetal force lab missing. You know who you are.

Honors 1:

Kurt we'll need to go over a=F/m

Sarah, ditto on Conservation of Energy

Missing Electrostatics lab from Amber and Miguel

Hi Carly, you should remember to enter date and period on all labs, just the way Ashley( hi, Ashley) does it.

Honors 2: Jen got your a=F/M and you are done but see my notes. By the way, nice notes on electrostatics.

Missing electrostatics labs from Tony, Maria, Armin, Eric, Dean. Monday is last day!

2) Late homework will receive some partial credit. Enjoy tomorrow but keep plugging and finish your assignments.

3) Cannot check email because I can't reach our server ( again.)

AP and Honors Labs and Assignments

Total of 6 items. Read all the way down to 6 (skip AP or Honors as appropriate)

1) ALL Labs: Here is a link to what labs my records show are overdue to be turned in or are t be resubmitted. If your lab has a grade you want to improve upon, other than what is shown here, I will try to get to it. If you have a lab that is listed as resubmit on it but you are satisfied with the current grade, turn it in anyway with the word STET written on it in large letters. ALL labs where data was complete on last Tuesday will be accepted only on MONDAY. Torque labs not yet completed are due Wednesday. All labs first received after their original due date receive reduced grades depending on how late they are, as do resubmissions that are received more than 6 school days after they were returned to you. However, low grades are still much better than zeroes.

http://h1.ripway.com/DrCherdack/Grades%2011-4-labs091st.xls

2)AP extra credit problems: Do this for homework

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

3) Honors Assignment: Review last test[ DO NOT DOWNLOAD THIS FILE IF YOU HAVE NOT TAKEN THE TEST YET] Here is a link to the test. You may NOT print this out and you must destroy the file after Monday. Your homework is to make sure you can do every problem on this test. Approach it as if you were to take it again on Monday and you need to get 100 on it. [No I did not say I was going to retest you, but act as if I did.] Work with your project/study groups and email me if you are really stuck.

http://h1.ripway.com/DrCherdack/Unit%204ElectrostHnrsquiz2%2009-10.doc

4)AP look for a new unit schedule mid day Sunday.

5) Honors : We will get to Gauss and flux Monday and Tuesday so try your best with the book and notes and homework.

6) See earlier post re bringing lab data for Spreadsheet lessons

AP and Honors

1) For labs next, week we will be working with spreadsheets . On Monday, Honors classes should bring in their a=F/M, acceleration, and Conservation of Energy labs. AP 1 bring in your Moving Cart, a=F/M and centripetal force labs on Tuesday and AP 2 do the same on Thursday.

2) All "see me" and resubmit labs must be in by next Monday. Remember, every lab has a purpose of testing an hypothesis, often expressed as an equation. How well the hypothesis was confirmed should be discussed in your conclusion. All data needed for me to check your results and calculations should be included in the report as well equations used, and preferably at least one sample calculation.

3) Test results were a lot closer to what I feared than to what I hoped.


4)Grade were posted in Home Accident. They do not include yesterday's escapades. Also, for many of you the lab grade was a guess because there are so many outstanding resubmits or missing labs. Many of you should be coming in to discuss your lab status.

AP Sheet R-2 Solutions

For the faint of heart, here are the solutions:

1)rboy =25 xg x1.5/( 33 xg) =1.13 m

2) M2 =24 x 1.5/1.25 = 28.8 kg

3)M2 g= (-20 g x 0.5+25 g x 1.0)/ 1.75 or M2 = 8 kg

4) take torque around east pier Fwest = (7.5x10^6 x100m + 5x10^6 x150m)/200m = 8.25x10^6N
Feast total weight - Fwest = 13.5x10^6 - 8.25x10^6N = 5.25x10^6

5) FT cos 30 = 500Nx.8m/1.6m =250 N FT = 250/cos30 = 288N

Honors Homework

Try to get Gauss' Law and flux homework in by Wednesday morning or after school Wednesday. Spend tonight studying. Make sure you know the ideas from last week's quiz and how to apply them. Know the difference and relations between fields and forces and voltage and PE.

AP Advanced Study assignment

Complete the advanced study assignment for the torque lab by Tuesday

AP Unit 3 retest

I f you scored below 78 on the Unit 3 test you can take a retest any time between after school on Tuesday and 3:30 on Wednesday ( that's the finish time not the start.)

All AP Components Labs

I have nearly finished grading the Section 2 labs and most of them are awful, however much of this applies to reports from both classes. Many have no data on the hanging mass used to find Fg// or the reading of FN using the scale. The purpose of the lab is to see if using Fg cos theta vertical for Fg// and Fg cos theta horiz for Fgperp works. How are you to compare your calculated values to the real values if you do not record or show the real values? Just because you did not receive a nice, pre-made data table which had blanks for you to fill in, doesn't mean you were not responsible for recording data.

Some of you continue to leave out the calculations you made to find values. You must include at least the equations you used and all the data used to arrive at your predicted or expected or ideal values and your value calculated from measurements. For example Fg// predicted = Mcartg x h/L and Fg// actual = Mhanging x g.

Many of you used the cos, h/L, to find the angle using cos^-1 on your calculator. You then found the cos from cos of the theta you found from the cos^-1. This shows a level of incomprehension that is alarming. You found the angle from the cos and then found the cos from this angle. I guess you have a lot of time to waste. [By the way, you should know that a^-1 x a = 1 ]. You didn't need to find the angles since h/L = cos theta vertical and b/L = cos theta horizontal [or use 1- (cos theta v) ^2 = (cos theta h) ^2]. Your depedence on your claulators for finding everything is scary.

Many of you talk about the spring scale not giving an accurate reading for Fg//. Well, we didn't use spring scales for Fg// did we? We used hanging masses and they gave very accurate readings as long as you counted the masses properly and didn't have anything jamming your pulleys.

You will have until next Monday, 11/9 to correct these disasters, but this will be the last lab for which I will allow this kind of resubmission. Many of you will have to re do the lab this week becuase of your failure to record the data.