AP Rotational Motion Updates

See Honors Post of today 12/30 for updated definitions and notes on angular quantities and rotational motion and torque.

Honors New Rotational Motion Schedule and Sheets

Here are new schedule and notes and problem sheet links . Lots of changes to schedule; changes to definitions and notes; changes to notes should make them easier for you to understand. R-3 hasn't changed from original post, just here for convenience. On the planet worksheet make sure you find and open the planet data form sheet

HonorsUnit7Rotsch07-8r1.doc

RotMotionDefseetc-07.doc

NotesonTorquerev12-30.doc

PlanetWS.xls

ProblemSheetR-1rev1.doc

ProblemSheetR-2.doc

ProblemSheetR-3.doc

Honors and Mathematical Quizzes

There will be brief quizzes tomorrow:

Honors on circular motion;

Mathematical on derivation of equation for finding vinitial

AP Fluids Solutions

Here is the link to my solutions to the text problems on fluids. Use a little a caution, I may be careless at times.

Solutionstotext.doc

Centripetal Force Lab

Centripetal Force Lab writeups can be informal

Urgent (well, sort of) AP Year End Schedule

Somehow our server managed to combine two  schedules and upload a garbled mess. ( I think there is a "buffer" that stores intermediate unsaved versions of documents and then when the occasional failure occurs substitutes the version stored in the buffer for the one that was supposed to be saved.) I have since uploaded the correct schedule. try the link now

Honors and Mathematical projects

Turn in your proposals for a project tomorrow or Wednesday the latest. A poster or a constructed object with explanation on some topic we have covered or will cover this semester.

Honors Schedule for Unit 7 Rotational Motion

Here are links for the new schedule and for the materials you will need now. Watch for future posts of additional material.

HonorsUnit7Rotsch07-8.doc

RotMotionDefseetc-07.doc
ProblemSheetR-3.doc

NotesonTorquerev12-30.doc

AP Fluids extra problems

Here are some extra problems for the gluttons amongst you.

Unit7ExtraProblems.doc

Honors Quiz

AP Fluids Practice problems #4

There is a typo in Problem 4 of the Fluids practice problems . In parentheses it should say:
1.013 E5 = 1 Pascal

AP New Schedule

Here is a new schedule to take you through the next two weeks. Do keep checking the blog, you never know what goodies may appear

APYearendsched07-8.doc

Honors Homework, new Fusion Fuel Calculation

Homework for Monday.

Use the blog if you can understand it, but the fact that this blog can't show exponents or subscripts makes it hard. Here is a link to the same information in a Word document.

DHe3problem.doc

which should be easy to follow.

Follow the process, and make sure you understand it, don’t just fill in the blanks blindly. There will be a quiz on this early this week.

The deuterium - helium 3 (D He3) reaction is perhaps the most desirable of all the easily achievable ones. The products are helium 4 and a proton. These particles are charged and can be confined by magnetic fields. They also do not interact with nuclei in the materials around them ( i.e., the reactor vessel) to make them radioactive.

Let’s investigate how many reactions per second and then how many fuel nuclei per m3 it would take for a D He 3 fueled power plant to put out 1 billion watts. Assume 40% efficiency so we need

10E9(J /sec )/.4 = ____ joules /sec of energy from the reactions.

Each reaction produces 18.4 MeV or ______J

The number of reactions per sec x the energy per reaction = energy per sec from the reactions.
Therefore the number of reactions we need per second is found from

________/_________ = _________ reactions per second

This reactor will have to be substantially larger than the deuterium tritium reactor we talked about Friday; lets say 250 m3 instead of 100 m3. The number of reactions we will need per m3 per sec is simply the number of reactions per sec / volume of reactor. So in this case the required reaction rate = _________ reactions per sec per m3.

Remembering that the reaction rate i.e. the number of reactions per m3 per sec is given by the number of “bullets” times their speed times the number of targets x the area per target, i.e. we have:

reaction rate [reactions/(m3s)] = nD vD nHe3 sigma; where n is the number of nuclei per m3 (number density), vD is the average speed of the deuterium nuclei and sigma is the target area per nucleus. Recall that for maximum reaction rate we set the two “n”s equal to each other and therefore each n = 1/2 the total fuel density or nD = nHe3= nfuel/2.

Lets look at the velocity. With the DHe3 reaction we have one nucleon with one proton and one neutron, the D: and one nucleon with two protons and one neutron, the He3. Therefore the potential energy when the two fuel nuclei approach each other is now given by PE = kcQ1Q2/r [kc = 9 billion or 9E9]

9E9x1.6E-19 x 2x1.6E-19/ r . If we approximate r as 2.E-14 [ this may be a poor estimate and we will discuss the details of this tomorrow] we get PE = ______J.

This PE of the nuclei as they reach this close distance, must be equal to the KE they started with, so we can use this KE and the fact that mD x vD2/2 = KE to find vD of the deuterons circulating in the reactor. Recall that the mass of a deuteron, which contains two nucleons, is 2 x 1.67E-27, and rewrite the definition for KE to find vD and get vD =____________m/s.

From the literature we find sigma is about 7E-29 m2.

Rewriting the reaction rate equation as (nfuel squared/4) x vD x sigma and then rewriting it again so we can find nfuel ,

we have nfuel2/4= required reaction rate [i.e. reactions per m3per sec]/( vD x sigma) Multiplying both sides by 4 and taking the square root of both sides we find nfuel = ______ fuel nucleons per m3.

Congratulations, you just completed your second fusion fuel density calculation, and two weeks ago you couldn’t even define fusion.

Honors Homework and Sample Fuel Use Calculation

For tomorrow, complete all the calculations posted for you starting last Thursday. Also review the derivation of the elastic collision posted on Decemeber 4.

Here is a sample fuel use calculation

A power plant produces 500,000,000 watts of power. It produces power with an efficiency of 40%? How much deuterium and tritium (DT) fuel does it use in 1 hour?

It produces 500,000,000 J/s x 3600 s/hr = 1.8E12 J/hr. [ E12 means x10 to the 12th] To do this at 40 % efficiency means it uses about 1.8E12J/.4 = 4.5E12 of fuel energy per hour.

Each reaction produces 17.5 Mev which equals 17.5 x1.6 E-13(J/Mev)= 2.8E-12J

Therefore plant needs 4.5E12(J/hr) divided by 2.8E-12 J/reaction = 1.6E24 reactions per hour.

Each reaction uses 2 nuclei, one containing two nucleons and one containing three nucleons, for a total of 5 nucleons per reaction. This comes out to 5 x 1.67 kg per reaction. You are now on your own to calculate kg of fuel used per hour.

Mathematical Physics Unit 7 Schedule

Here are your schedule and work sheets for Two Dimensional Motion, Unit 7.

AND Remember a lab report can save your life.

CPMUnit72Dsched-07-8.doc

Worksheet12DMotionCPM.doc

Worksheet2forCPM2Dr1.doc

CPM2DWorkSht2B.doc

CPM2DWorksheet3.doc

Honors Energy Assignment

For Tuesday asnwer the following:

A typical fusion reaction produces 17.5 MeV per reaction and requires a deuteron with atomic mass 2 and a tritium nucleus with atomic mass 3. In other words an Avogadro's number of the reactions requires 5 grams of fuel.

How much fuel must be consumed per hour in a power plant that produces 1 billion watts at an efficiency of 33%? .

How many kg of this fuel would be consumed to produce the 1E20 J we estimated the US uses per year?

AP Rotational Solutions

Here is the link. This does not include text problem 55
APRotationalSlns0001.pdf

Mathematical Homework Momentum review

We will spend the next two days reviewing momentum, culminating in a quiz. 

FOR MONDAY, redo or do the momentum worksheet and problem sheet links are listed below.) Skip 8 and 9 on the problem sheet. The problem sheet has answers at the end, and  the link for the M-1 worksheet solutions  is posted below but no peaking until you have really tried on your own.

Use 

p =p'  i.e. m1v1+m2v2 = m1v1'+m2v2' 

and delta p = Jexternal = Fnet from external forces x  delta t  as needed for each problem. 

 For space module problem: Note that the explosion between parts of a system is internal not external. The force does not change the total momentum of the system but the two parts can have different momentums from each other after they are separated by the explosion.

Unit5HnrsProblemSheet.doc

MomentumWorksheetM.doc

MomentumWorksheetMsln.doc

Honors Unit 6A Energy production

In this unit we will determine the energy used by the US. We will then relatethis to the amount of fuel of various types that are required. We will then explore the reactions resulting in energy production particularly fusion and the required collisions between nuclei.

For Monday review all the fusion notes and the notes on heat and energy conversion.

Also do the following:
If 1 W = 1J/s and 1kW = 1000W then find:
how many J in 1 kW hour.

How many J do you use in 1 year if your house uses an average of 2 kW ( 31.5 million sec/yr)

If power is generated with 33% efficiency how many J of fuel energy is required?

if 1 eV = 1.6 x10-19 J how many eV in a kWh?

Energy for Honors Physics

We will spend the next few days in the enrichment mode, exploring particle collisions, energy production and the relationship between mass and energy.

To begin with try this out.

The energy matter contains is equivalent to the mass of the matter multiplied by the square of the speed of light. The average household uses something like 3 kW of electric power. Assuming that it uses this much power around the clock for a year ( 31.5 million seconds), How much matter will have to be converted to electrical energy to power this house. Take into account that the generation of electricity is about 35 % efficient. Turn in a decent calculation tomorrow  for some extra credit, but wait until we discuss it in class.

AP Fluids (Unit 7)

Here are the Schedule and Practice problems; the problem sheet;  a review sheet containing some questions and some notes; and some notes and a lab on Archimedes. This last item is what is meant by read lab on your schedule. 
APUnit7Fluidsched-07.doc

Unit7APProbSh-05R1.doc

ReviewSheetFluid06.doc

NotesonArchimedes.doc

Solutions to Honors nad Mathematical Energy and Work

Here is the link for the solutions


EnergyandWorkWorksheet1asln.doc

All Classes - Groups

Since groups are going to be such an importnat part of this class, I will allow you to have some say ( not the final say) in their composition. Therefore, please email me with your preferences. This is worth 5 extra credits for mathematical and honors students.

For AP students, this email is required and worth 3 homeworks.

Urgent: Group Meetings

Every group must have at least one meeting outside class hours for each subject ( unit). This goes for AP, Honors, and Mathematical.

AP must in addition meet at least once every two weeks no matter how long a unit lasts.

Every student must hand a brief report for each meeting covering : who was there, when it occurred, where it took place, and what was discussed and what work was done. Please keep this to about 2 sentences. It should take less than 5 minutes to write the report.

THESE ARE REQUIRED.

Since I cannot give Incompletes so easily, not meeting this requirement will result in losing a grade!!!!!

Homework and Outfolder

Check your outfolder every day. Many labs and assignments are left moldering in the outfolder.

If you distribute material from the outfolder, please return the t students rather than leave it on desks or tables where it can be damagged or lost.

Elastic Collisions

Here is the derivation of the equations for finding the final velocity after an elastic collision.

ElatCollderiv.doc

Momentum Lab

Here is a spreadsheet which has my take on the data and calculations for Honors Section 2. Note that the only big errors are for the last three trials. Looking at the data for these trials I see that cart A is consistently much slower then cart B. I suspect that cart A was in or very near the gate when cart B struck it. If this was so, the time in the gate would be longer than just the transit time associated with the initial and final velocities. This would give over long times and lower velocities for cart A which would probably explain the errors. If we have time sometime soon, we will rerun theses trials with a wider distance between the gates and see what happens.

CollisionLab.xls

AP Revised Notes on Torque

Here are notes on torque and Moment of Inertia. I hope we get to these soon.

NotesonTorquerev12-2-07.doc

Honors and Mathematical Worksheet solutions

Here are selected solutions to the worksheets from your classes last Monday and Tuesday. Use these to correct your work. There will be quizzes and tests on these concepts and problems.

WorkandEnergyWS-Asln.doc

PowerandEfficiencySlns.doc

Hnrunit6ProbShtsln.doc

AP Planet worksheet.

The Workbook contains a sheet called planet data form which is what you must use for the assignment. You may have to click on the the arrow in the extreme lower left to see it. When you do see it, you may see a bunch of ###s in the mass column. Just highlight all those cells and go to format then  cells then number and then choose scientific and 2 decimal places. You will see the sun has a mass of 1.99 E30. 

Note that the mass column labeled earth masses means exactly that. The sun has a mass of 333,000 earths NOT 333,000 kg. The earth has a mass of 5.98 E24 kg. Yes, the sun does have considerably more mass than a small freight train.

Please do not tell me that you think the period of the earth's rotation is trillions of years.

Honors and Mathematical Classes Momentum Labs

Make sure you have your momentum Labs and data with you this week. We will be going over it in class and in the computer lab this week. Read the blog posts on this lab; there are three posts.