Honors and Mathematics Weekend Homework

For this weekend , go over the sheets you did on Monday and Tuesday and make sure you have the correct method of solution. There will be a brief quiz on a couple of these Monday.

Most of what you need is written as introductions to the two worksheets. The problem sheet is a little tougher, but we went over the key problems in class. Do read the all the notes on work and energy posted onthe blog with the Unit 6 schedules on November 21.

Here are links:
WorkandEnergyWS-A.doc

PowerandEfficiencyWorksheet.doc

Hnrunit6ProblemSheet.doc

Conservation of Mechanical Energy Lab

For this lab, you obviously should compare the change in PE, from the point where the cylinder is released to the bottom of tis arc, with the gain in KE from the release point to the bottom. Since KE = 0 at the release point, the change in KE is simply the KE at the bottom. Therefore you should be finding out if Mg (hrelease- h bottom) = Mv(at bottom)squared/2.

We find v from diameter/t because the light is blocked for the time it takes the cylinder to travel one diameter as it passes through the photo gate. However, this is not quite accurate. The light is not completely blocked until the cylinder reaches the far edge of the bulb in the photogate head, and light starts to leak through once the back edge of the cylinder passes the near edge of the bulb. So in effect, the cylinder only has to travel its diameter - the bulb diameter, during the time the light is blocked. Even this is not quite right since the hole the light enters is much smaller than the bulb, so maybe the correct distance is cylinder diameter- hole diameter or something between the two. Think about it and you might use it to explain why your first calculation of KE may be greater than the initial PE.

Planets Work Sheet for AP

Here is the link. Use the sheet labeled Planet Data Form

PlanetsWS.xls

Correction to Honors and mathematical Unit 6 practice problem

The answer to the Unit 6 Practice problem 1 , how much fat you lose climbing the Empire State Building should be .062.

AP Momentum Lab of 11/20

Yes it is formal. You should include enough information to determine if the total momentum was conserved; i.e. ( treating momentum as a vector) see if the total momentum of the two carts is the same before and after each collisions. You should determine the percent error. You should also check to see if KE was conserved, i.e. was total KE the same before and after. Read the two posts on the blog for my Honors and Mathematical classes for the momentum lab for further details

AP Unit 6 Schedule Correction

I did it again somehow; another typo. For Tuesday night do Chapt 7 prob 21-24,26. For Wednesday do Prob sheet 1-6

Momentum Lab Take 2

For your lab reports percent error can be positive or negative depending on whether the final momentum is less than ( negative error) or more than( positive error) the original momentum.

For runs where both carts were originally moving, the percent error can appear to be unreasonably large. This is because to find the original momentum we add one large number positive number to a large negative number and finding relatively small difference between the momentum to the window and the momentum to the door. A small percentage error in the large numbers can cause a large precentage error in the relatively small difference between the doorward and windoward momentums . Then we do the same to find the final momentum and compare the two. If we take the initial total momentum ( total meaning taking windoward as positive and dorrward as negative for example) minus the final total momentum and divide by the intial total and multiply by 100we can get a very large percent error, because we are dividng by the difference between two large but similar numbers. In order to get a real sense of the percent error, try taking the final total from the initial total and then dividing by the sum of the magnitudes of the initial doorward and initial windowward momentums, (i.e treating both windoward and doorward momentum as positive in the denominator). Of course multiply by 100 to get the error in percent.

AP Rotational Motion and Gravity

Here are the links you/ve been waiting for. You didn't think I would abandon you over the holiday weekend, did you?

Do enjoy your holiday, remember to be thankful for all the good things you have.

APUnit6sched07.doc
Some useful notes on the subject. Do read them:

RotationalMotionDefnsetc.doc

NotesonTorque.doc
planetsorSatellitesinOrbit.doc
Sheets you need for homework
APUnit6ProblemSheet.doc
I think I called these WS R-1 and R-2 on your schedule. Whatever I called them, here they are:
ProblemSheetR-1.doc
ProblemSheetR-2.doc

Mathematical Honors Unit 6 Schedules and WorkSheet

Here are new links. Make sure you read the notes on Work and Energy
All:
NotesWorkandEnergyR3.doc

EnergyandWorkWorksheet1a.doc

Honors:

HonorsUnit6EWsch-07.doc

Mathematical:

CPMUnit6EWsch-07.doc

Momentum Lab using Carts

For the Momentum lab, we gathered data from several collisions. Ideally the total momentum of the two carts ( p1 and p2 added together) should be the same before and after the collsision.

For this lab, you should describe the procedure, carefully outlining which series of trials had M1 (or MA) greater than M2 (or MB); which series had M2 greater than M1 and which series had M2 as well as M1 moving before the collision.

You should have your original data tables. Use the time data to ind t1, t1', t2, and t2'. Be careul remember which times are from before the collsion and which are after. Remember to subtract where necessary and that t2 did not exist for many cases and t1' didn't exist for some.

For results discuss which cart moved which way after the collsions. Then find your v1,v1', v2 and v2' keeping track of which are positive ( toward the windows, as we did it) and which negative. Do the math for each trial to see if

m1v1 + m2v2=m1v1'+m2v2'

for each case. Find the percent error and see if momentum was approximately conserved. Discuss why differences may have occurred.

URGENT TO ALL

There has been a failure on the hosting site I use for documents. Please refer to my oncourse website homework events. There are important Unit 5 schedule revisions , Unit 5 worksheets posted 11/12 on the calendar and an AP derivation posted on 11/13

Honors and Mathematical Homework

You do not have to do Problem 11 on the Problem Sheet. We will cover this later

DuPont Science Essay Contest

There is a science essay contest sponsored by Du Pont with monetary rewards and a possible trip to NASA and Disney World.

Contact me if you are interested.

Momentum Worksheet for Honors and CPM

Here is the link to the momentum worksheet and the problem sheet. Both CPM and Honors should do these as described in your schedules. We will go over this in class

MomentumWorksheetM.doc

Unit5HnrsProblemSheet.doc

Rev 1 AP Unit 5 Momentum Work and Problem Sheets

Here are the links

Unit5Worksheet1.doc


Unit5Worksheet2.doc

Unit5ProblemSheet.doc
Unit5extraproblems.doc

Mathematical Important Homework and Test results

While most of you did improve on your first force test score, the test results were very disappointing except in 4 instances. Many of you still fail to grasp the basic concepts of force. You must realize that we are studying the real world, not some arbitrary nonesense. Physics explains what you see and feel every day. It will match your experiences if you observe them and interpret them intelligently.

For example, you all know that the force gravity exerts on an object depends on the mass of the object. The force of gravity on a car is not the same as that on a mouse. IT IS NOT 10! it IS Mass x 10N/kg.

Objects on the ground or on table tops or other surfaces do not fall through the ground, table top, or other surface. In addition to force of gravity, these objects experience a normal force upward and opposing gravity. In the absence of any other vertical forces this normal force is equal to and opposite gravity. These two forces together than add to zero force net perpendicular to the surface.

Gravity does not make things accelerate horizontally.

You know things sliding on ramps do not acclerate at the same rate falling objects do, and that the steeper the ramp the faster they accelerate. This is partly because of friction, but mostly because the force pulling down the ramp is only a component of gravity not the whole Mx10. You know it is easier to walk up a ramp then to climb a vertical ladder. This is why.

Some of you are still in the mode of taking whatever numbers are in front of you and putting them into the simplest equation at hand. For example, several students tried to find the force of tension in the rope between two masses on a horizontal surface by subtracting one mass from the other. Force cannot ever = Mass1 - Mass2 period. Force is not the same kind of quantity as mass. The correct answer is found by applying the fact that the rope is causing the second mass to accelerate. This relationship, F on the object =Mass of object x acceleration of object, is a keystone of classical physics, and something we have been studying through experiments, reports, demonstrations, class problems, and discussions for three weeks.

It seems that your observing demonstrations and experiments and reporting your results; my writing on the board; and our discussing things in class, is not sufficent for you to retain some basic facts Therefore you will turn in as homework the following.

Write clearly ten times each

1)Acceleration in a direction = the sum of the force components in that direction divided by the mass being accelerated

2) The component of a force in a direction is equal to the force x the cos of the angle between the force and the component

3) Force of gravity on an object (N) = Mass of object(kg) x 10 N/kg

4) The unknown force on an object in a direction = Mass of object x acceleration of the object in that direction - all the known force components in that direction, with the signs of the force components indicating whether they are positive or negative in that direction ( - means opposite of positive direction)

5) if the component is in the same direction as the force, then the component = the force


This is due Monday, and failure to turn it in will reduce your quarter grade by 5 points, spread the word.

There will be a retest on Tuesday. Note taking is now required and will be reviewed and graded for the forseeable future. Bring the equipment you need to take notes every day.

Unit 5 Schedules for All

Just so you don't have to suffer from withdrawal symptoms from your favorite activity, here are you Unit 5 schedules. In additon, Mathematical students can think of a physics question or topic for discussion

APUnit5MomentumSched07.doc

CPMUnit5MomentumSched07-8.doc

HonorsUnit5MomentumSched07-8.doc

Vector Lab for all classes

The vector lab required you to make two drawings one adding vector A to vector B and comparing the result, vector B+A, to vector C. This result points from the origin (the knot) to the end of the vector A that you stuck onto to vector B It should be a vector as long as C ( i.e. the same magnitude of force) pointed in the opposite direction, but don't fake it.

The next drawing required you to add vector B to vector A and then add vector C to the end of the vector B that you just placed on the end of vector A.

Note that vectors do not add as simple numbers. While vector A + vector B may add to - vector C it does not mean that magnitude of A + magnitude of B equal magnitude of C.

In your drawings you may think of magnitude as length although the length stands for force strength.

Honors Labs

Tomorrow is the last day for you to get your first quarter labs to me, including the one with two weights providing a net force.

AP Consrvation of Energy Lab with Ramps

I will need a complete description of what you did to evaluate your labs. Therefore it is a formal writeup this time. I'll make it due Wednesday to help reduce the pain.

Honors Fnet = Ma? with 2 weights Lab

Most of the period 2 labs and some of the period 4 labs missed the point again. You were supposed to find the ideal Fnet from M2 x 9.8 - M1 x 9.8 and then compare it with Mtotal x a measured to see if Fnet = Ma. Mtotal = total cart mass plus M1 and M2.

Any difference can be ascribed to friction.

A similar approach to the first a=F/M lab is described in posts of 10/21 and 10/24. Read them now, especially if you still have an a=F?M lab to submit or resubmit.

AP Lab Resubmittals

The resubmittals are very disappointing in many cases. Most of you did not fix the major problems with your lab and did not seem to even bother reading the extensive blog posts on the a=F/M lab(see posts on 10/21 and 10/24.) In the future, if you resubmit a lab with the same major errors, ignoring the comments I write on your paper AND on this blog, I will deduct points from your existing grade. I have enough to do without wasting time seeing the same errors a second or third time. How you can say your lab demonstrated F=Ma without your even knowing what F is, continues to amaze me, as does your thinking that a 100g mass produced 100 N of force. In future quarters, resubmittals will only be accepted where I specifically ask for them. Failure to resubmit will result in the original grade being entered in your quarter grade. Failure to respond to a see me will result in a ZERO for the lab.

If you do not know what you are doing, see or email me BEFORE submitting a faulty lab report.

To Parents and other HAC users

I have now posted most assessments for all classes on line and they should be accessible to the HAC. Do not pay any attention to the student averages. Eschool cannot calculate grades the way I do, adjusting for a students particular learning styles and abilities. If what you see causes any concern, please email me.

One area that you may want to pay particular attention to is the lab assessments. Please note that low grades on first quarter labs can be raised by resubmittals, but please know what was wrong and how to correct it before you create your resubmittal and ask me to grade it. While I am flexible about many things, grades will include a signicant lab component since about 20% of of the course credit is based on it being a lab course.

Grades of "other" mean that while the item was received, for one reason or another I did not award a grade for it. Students must see me about these items or they will become zeros at marking time.

The purpose of attending school is to learn, not to be judged, and a grading system is at its best when it encourages learning. Please use the information available to you help your student learn.

AP Unit 3 Retest

All students who received a score of less than 75 on the the Unit 3 test may take a retest on Monday or Tuesday outside of class hours. You must email me if you plan to take it.

If you take the test on Tuesday, it must be before 6th period. It is advisable that ytou get help before taking the test. The maximum grade you can receive will be equivlanet to having scored a 75 ( equivalent to a B-) on the orignal.

AP Unit 4 Problem Sheet

Just in time, I hope

unit4ProblemSheet.doc

AP proof of Pulley system a of center of mass=F/m

Here is a link to a brief proof that when you include all the forces acting on a weight / pulley system, the acceleration of the center of mass = Fnet on system/ mass of the system

Atwoodcomprf.doc