AP Boat Lab

Add a purpose and conclusion. Were we trying to demonstrate something? Did we succeed?

I think I've got it where I want it with respect to the calculations I'd like you to make. The extra lab credit is unusual in that it will be applied to your lab grade directly.

http://h1.ripway.com/DrCherdack/ferryman%209-10.doc

Torque on Honors Test

Since we have covered torque in class and especially in our labs, it is reasonable find out what you learned about it. If you can handle problems of the level of difficulty (not necessarily the same type) of question 6 on your torque lab, you should be okay.

There is a post discussing question 6 in you lab from last Sunday. It might help you.

Forces on Objects and Systems

Notes on Forces

A) Note that any single object, call it object A, is affected only by the forces acting directly on it including only contact forces (such as from ropes or table tops)and field forces( such as gravity. This means that only forces from objects in contact with object A or producing a field such as gravitational or electrostatic, which interacts with it, can directly cause object A to accelerate.

For example, without taking into account air resistance and other minor effects, the acceleration of an object hanging from a cable is affected by only two forces, the tension in the cable and gravity. Similarly, the tension in the cable where it is attached to the object can be found by considering only the acceleration of the object and the other force on the object and keeping in mind the respective directions of the forces and of the acceleration.

B) Objects in a system linked together in a way so that they all accelerate and move together can be treated in a sense as a single object with a single mass equal to the sum of the masses in the system and accelerated only by external forces. The forces internal to this system cancel each other as far as accelerating the total mass is concerned. This is because the force of one object in the system on a second object in the system is equal and opposite to the to the force of the second object on the first. Thus they make no contribution to the net force on the system as a whole.

However, once you have you used the external forces on the system and the total mass of the system to help you establish the acceleration of the entire system, and thus each object in the system, go back to Note A above to find the internal forces such as tensions in a cable connecting two objects in the system.

To those interested in medicine.

There is a program for doing something like internships with doctors over the summer. I don't know much about it other than some of my students in the past thought it worthwhile. It is expensive but some aid may be available. If you are interested let me know by email and put NYLF in the subject line.

Honors Assignment and Quiz

This assignment for tonight should reinforce what we accomplished in the last two days:

http://h1.ripway.com/DrCherdack/Worksheet%20F9-92-09.doc

Get all your force homework up to date. You should fix everything turned in so far, but you don't have turn it in again.

The quiz is this Thursday.

Honors Lab on a=F/M

1) It has been pointed out to me that I never defined mechanics. While this is an overstatement, I'll say here that mechanics is the study of forces and their effects, on bodies, and structures. Mechanics quantities include position, velocity, acceleration, force, mass, etc.

2) Item 9 in the lab sheet asks you to use your graphs to find out if the purpose of the lab has been accomplished. Ignore all the words in parenthesis, they are from an earlier version.

AP Relative Motion Sheet

Here is the revised Relative Motion WS. Use this tonight.

http://h1.ripway.com/DrCherdack/Relative%20Mot%20WS%20RM9-09.doc
Here is a key correction to problem 6 from this new version that corrects the error in the old work sheet


6. A ball is thrown from a car heading north at 20 m/s. From the car the ball appears to be heading forward at a 45 degree angle at 15 m/s. What are its vertical and horizontal velocity components wrt the car and wrt the earth?

AP Worksheet 3

Sorry guys. Here's the link
http://h1.ripway.com/DrCherdack/Unit_2_Worksheet_3.doc

Honors Secton2

I spend my weekends grading your labs and reviewing homework. You did not pick up material from the outfolder. Starting Wednesday labs will receive -5 points for every day left in the out folder.

AP Vector Lab

Purpose was to show graphical addition of vectors, i.e., tail to head method, worked and was commutative. We assumed, for now, that the three force vectors should cancel since there was no motion. When B+A = -C and A+B looked just like B+A and A+B+C =0 this seemed like a pretty good demonstration that tail to head worked and was commutative.

Many of you did not add vector C to vector (A+B) as requested in paragraph B. All you had to do to find A+B+C was transfer vector B so its tail lay at the head of vector A and then transfer vector C so the tail of C was at the the head of vector B, that is the vector B in its new location. The vector A+B+C was a vector starting at the origin and going to the head of vector C in its new location. It should have been very small or even zero in magnitude.

Some of you did not provide any sketches at all. You will have to do them to get a grade.

A few of you added vectors as if they were simple numbers. This is very wrong. A force of 3 N to the left plus 3 N to the right = 0N not 6 N. A force of 2 N to the northeast plus a force of 2 N to the northwest = 2.83 N to the north not 4 N north or anywhere else.

Honors Physics Topics Groups

By Tuesday have a name for your group. Something that you can start building some enthusiasm around. A simple example is the "The Magnetics" for the electricity and magnetism people, or the "The Surfers" for the ocean waves guys, or maybe this is more appropriate for the TV group. Also, start thinking about a logo. Last year two groups even made tee shirts with their logos.

Speaking of last year: Hi to Ashley, CaCarly, Amber and Neel.

Labs in General and Torque Lab

All of you should read all of this this because AP will do this lab soon.

With few if any exceptions, the purpose of a lab in our class is to test the truth of a theory or hypothesis or more than one hypotheses. It is NOT to gain experience in balancing, it is NOT to study the effects of moving a balance point , it is not to educate you or give you a feeling of accomplishment. It is to see if something, usually a pretty specific something, is true.

The reason for me requiring you to do a lab, or my purpose for you doing the lab is another matter, and may be something really sinister, such as getting a teenager to think. However this is not the purpose of the lab in itself. It is the purpose of the lab itself that you must put in your report, not any of my or your ulterior motives (which in your case may be simply to avoid getting yelled at by an irate physics teacher.)

Similarly, the conclusion must contain a direct answer as to whether or not the purpose was achieved, i.e was the truth of the hypothesis or hypotheses demonstrated. This should include a restatement of the hypothesis, hypotheses being tested.

For the torque lab, the two hypotheses being tested were

1. Given the definition that torque = Ftangential x distance from point of rotation, then if the clockwise torques = the counterclockwise torques rotational equilibrium is attained,
2. For calculating torque, the weight or force of gravity on an object can be taken as acting on the point which is the center of mass of that object.

Cases 1, 2 and 3 demonstrated the first hypothesis and case 5 demonstrated the first and second.

Question 1 on the torque lab asked about how the sum of the forces = 0. IT said nothing about torque. Many of you made the double mistake of saying the forces were equal on both sides of the pivot. First this was not true, the torques not the forces , were equal. Second the question was not about rotation and torques it was about force. All the weights were downward forces, why did the meter stick not accelerate downward; i.e. what was holding the meter stick up and with how much force?

Question 3 Triple beam; since you never got to use these in chem lab I'll have to explain it to most of you although congratulations to the few who did get this right.

Question 4: your answer should have had a calculation which showed the torque required from mass 3 had to be 4500 gram cm. You could then explain why this was a problem with

M3 = 50 grams and how you might solve it moving M1 or M2 or even the pivot point.

Question 6 should be answered. Write an expression for the ccw torque using 220 g and its distance from the pivot and an expression for the cw torque using 100 g and its distance from the pivot and the mass of the meter stick ( unknown so call it M3) and its distance from the pivot. Set ccw equal to cw and solve for M3. Remember distance is not position, i.e. d not equal x.

Also remember that x means position, not mass, not speed, not force, not torque.

Everyone Meetings

Physics Club ( the coolest club of all) meets at 7:05 in my room (506). Anyone with an interest in physics is welcome.

People who want to participate in Physics section of Science League should meet with Mr. Gilmore at 2:30 tomorrow ( Thursday) in Room 502.

Honors : Net Force

In doing the work sheets remember that we were a little sloppy in class. Its not F = Ma it's Fnet = Ma or a + Fnet/ M. For example, if I have a 2 kg mass being pushed by a 4 N force to the north and an 8 N force to the south, the net force on it is 4 N to the south and the acceleration is 4N / 2kg = 2 m/s/s to the south.

Remember the force of gravity, i.e. the weight, = Mg and is down and has to be taken into account when figuring out what the net force is.

Grades

I have just finished posting your grades so you should be able to see them in the High Anxiety Creator (HAC).

Note the following.

1) AP s: If you have no tests grade I expect you to be taking the retest on Wednesday. If you don't plan on doing that, let me know. If you do plan on taking the retest you need to have attended at least one extra help session between Thursday and Wednesday and you must have at least a 95 in homework on Tuesday

2) Honors projects: everyone got 100 so far if they turned in project choices. Three in Honors 3 got zeroes.

3) Homework see me if you take exception. We did lose some data last week. Lots of technical problems and a few human ones.

4) The overall grade posted by HAC IS NOT YOUr TRUE GRADE. Just look at the individual categories. HAC cannot provide customized weights as I do.

5) Focus on learning and understanding and doing the work and the grades will take care of themselves

E mail and Honors Topics

Our beloved email system will not send emails from me. I can only receive right now. I now have topics from all but D'Arcy, Lefler and Kauffman. I have assigned topics to everyone.

Honors Assignment Schedule

Here is your schedule for unit 2 forces and acceleration

Read the previous post. It also won't hurt for you to read Monday's assignment tonight.

http://h1.ripway.com/DrCherdack/HonorsUnit2Sched10-11Force.doc

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

http://h1.ripway.com/DrCherdack/Force%20Worksheet%202.doc

http://h1.ripway.com/DrCherdack/WorksheetF-2Hnr.doc

All students Rates of Change, Velocity, Acceleration

A rate of change is the amount a quantity changes divided by the the time it takes the change to occur. More formally this is the rate of change with respect to time.

For example, velocity is the rate of change of position. It equals change in position/time it took to move or

or v = change in position/change in t

One can take a rate of change and the time and use it to find the change in a quantity: change = rate of change * time it took

For example change in position = v * change in t [* means multiply]

Velocity is not constant if uncancelled forces are present (net force actually). The rate of change of velocity is called acceleration, a.

a = change in v/ change in t change in v = a * change in t.

An example of this is a book on a table, the table pushes up on the book as hard as gravity pulls down on it so the forces cancel. Take away the table and it falls, but not at a constant rate. It starts out with v initial = 0 and then falls with increasing velocity falling faster and faster until it hits the floor and the floor's upward force stops its motion and cancels gravity. Do you think the force on the book when it first hits the floor is much greater than when the book is at rest on the floor? Think about it. Did the floor create a very large change in the book's velocity at first. Would this require a large upward force?

AP Clarifications on Homework Schedule

Vector Worksheet2 is just Unit 2 Worksheet 2. The answer for problem 3a is 7.51 deg above the x axis. The MS Word document lost some formatting for symbols.

Honors Project Topics

I am still missing topics from several students in Honors 3 ( 7th pd.)


D'Arcy, Christopher Samuel
Harada, Kathryn Yuki
Kauffman, Erica Allison
Lefler, Joshua Patrick
Tobia, Jacqueline Grace
Trentesaux, Adrien, Damien
Tuohy, Shannon Simone

If I do not get email from you by noon Sunday (today), I will assign topics and deduct credit.

All students Location Assignment

I would like to know about where you live so I can organize project and study groups in each class. Please go to maps.google.com and look up Basking Ridge. Find your home and print out a map with your home on it. I don't need your exact location but get it within about 1/5 of a mile or so. Write your name neatly about where you live. Bring it in Monday. You don't have to use google if you have another source for the map.

If you think this is too invasive just send me a note and I'll try to assign you to a group some other way.

Labs

All labs should have your name; section number or period; date the lab work (not the report just the data taking part) was completed and the lab partners at the top, even if the lab sheet doesn't have a space for these things.

Again, ALL labs must have a purpose section and a conclusion section.

Honors labs on torque are due Tuesday.

AP Labs

1) Falling mass lab.
Its formal
Note that you cannot find the value of the last two columns for the first row because you do not know what v zero was ( it was already moving by the zeroth dot.)
Plot the cumulative distance (when I said plot the displacement , I meant the displacement from the origin which is the same as the position).

2) Vector lab. Section 5 due Tuesday, Section 4 due Wednesday

I did not show Section 5 how to move a vector from the origin to the head of another vector while maintaining its direction, so I'll try to explain it here. Let's say you want to add vector A to vector B. Thus you want to draw a line that is parallel to vector A, which starts at the head of vector B and is just as long as vector A. Take two rulers or other objects that have straight sides and ends at right angles between their sides and bottoms. Place the first ruler so its edge lines up on the vector you want to move, let's call it vector B. Place the second ruler so its edge lines up with and fits snugly against the bottom of the first ruler. Hold ruler two firmly so it doesn't change orientation. Now slide the first ruler keeping its bottom tightly against the second ruler's edge until the edge of the first ruler lines up with the head of vector B. Use this edge to draw a line which will be parallel to the original vector A. The new vector A will be on this line starting at the head of vector B and equal in length to the original vector A.

Every lab needs a purpose and a conclusion. The vector lab should have these plus two diagrams ( B+A and A+B+C), and answers to the questions directly on your lab sheet.

All labs should have your name, date the lab work was completed ( today in this case) and the lab partners at the top, even if the lab sheet doesn't have a space for these things.

Honors Project Topics

I need to have project topics from the following people, either you did not submit them or I missed noticing them amongst the other homework you turned in. E mail me your topics by Sunday morning so I can get your groups established. If I don't get an email from you, I will assign you to a group and you will also lose some credit. Please do not let this happen. Have a nice weekend

D'Arcy, Christopher Samuel
Harada, Kathryn Yuki
Kauffman, Erica Allison
Lefler, Joshua Patrick
Tobia, Jacqueline Grace
Trentesaux, Adrien, Damien
Tuohy, Shannon Simone

AP Section 5 Lab

You were asked to leave your setups and rulers in place , but told to return the scissors and string to their respective storage places. The string and both scissors were left out. Next time the offending group or groups who do not follow requests for cleanup will lose one letter from their lab grades.

AP Assignments

Here are corrections to the schedule for home work due Monday and Tuesday



For Monday 9/20 Read Section 3.7 Do problems

47, 20, 31, 63

For Tuesday 9/21 Do Unit 2 Worksheet 2 prob1 and 2; Chapt 3 prob 51, 68, 69, 75

For all about Labs

Using today's vocabulary, formal lab reports are the default. Formal labs are required unless you are supplied with a lab sheet from a manual or unless I explicitly tell you otherwise. Even with a manual sheet you need to supply a purpose and conclusion.

Just answering questions provided in my labs is not enough for analysis and discussion.

See the course guide for what is required.

Honors

Go through the lab. Make sure your errors are less than 2%. If not see me tomorrow.

Be ready to finish it quickly tomorrow, i.e. take much less than one period. Remember you need to do only through case 5c to complete the lab. For case 5 make sure you understand that one of the torques is provided by the meter stick itself. In case 5a we analyze it assuming that all the mass of the meter stick acts at the original balance point (very near 50 cm) . Does your analysis for 5a provide an acceptably small error?

(From now on we are assuming you are facing the meter stick with 0 on your left and 100 on your right)
For case b analyze it by treating the meter stick as two pieces but ignore the piece on the short i.e.left side (this is obviously a mistake so we should get a big error). The large piece has a mass = total stick mass x (100cm - the new pivot point)/100cm, i.e. that fraction to the right of the pivot. This mass acts as if it was all located at the middle of the piece of stick to the right of the new pivot point, ( this should be somewhere around the 65 cm mark or more precisely at: new pivot + 1/2 [100 -new pivot]). This will provide a clockwise torque. You will probably get a 20% or so error for 5b.

For 5c you start with 5b and then add the torque from left side of the meter stick in to the counter clockwise torque. The left side has a mass of total stick mass x (new pivot/100). The torque is as if all this mass were at the center of this piece of this part of the stick i.e., at new pivot /2. Adding this counterclockwise torque in should get you back to pretty low error.

Honors balancing WS Solutions

Here are the solutions to last Friday's work sheet. If you don't understand them come see me.


http://h1.ripway.com/DrCherdack/BalancingWS1slns.doc

Honors Assignment

Your assignment for tonight is twofold.

1) Write a clear purpose for the torque lab. Remember why perform labs ( experiments) in this in general.

2) I hope that many and perhaps most of you now understand a lot more about torque and balancing, so your assignment is to go back and do the problems you couldn't do before. You should be able to do all the problems from the in class worksheet (especially the last one with the off center meter stick), the book stack problems, and most of the book problems. Section 3 (7th period) should all be able to do the piano and beam problem from the book. Section 2 should try it again, and we'll go over it tomorrow.

I'll post the solutions for the in class problems soon

AP Quiz

For tomorrow's quiz expect to find the 3 equations relating displacement to vs, a and delta t given on the test. However, you must know the definitions of displacement, v, and a. You should also know how to find delta t if given delta x and v avg or if given delta v and a. You should be able to get expressions for v final or v initial or t using the delta x = (vf^2-vi^2) /2a as a starting point.

Honors Assignment

Read the Torque Lab and try your best to do the Advanced Study Assignment. We'll talk about forces tomorrow. Wednesday and Thursday wear closed shoes, we'll be using hanging weights.

AP Unit 2

Here is your new schedule and materials for 2 dimensional motion, vectors, and relative motion. Life is good, right?

For the lesson for 9/20 on your schedule, please change Constant y to Delta y =0.

http://h1.ripway.com/DrCherdack/APUnit2Sched10-11.doc


http://h1.ripway.com/DrCherdack/Unit_2_problem_sheet.doc


http://h1.ripway.com/DrCherdack/Unit_2_worksheet_1.doc

http://h1.ripway.com/DrCherdack/Relative%20Mot%20WS%20RM10-08.doc


http://h1.ripway.com/DrCherdack/Unit_2_Worksheet_2_.doc

AP Text Book Problems

Many of you did not get the purpose of the some of the Chapter 1 problems. The point was not to get numerical answers, but rather to develop a visual and intuitive understanding of motion. Perhaps you did not "get it" because I didn't really cover it in class.

For example, Problem 37 would show downward arrows of increasing length as the melon descends. The space between successively lower points would become larger. In problem 40 the problem with the wad sticking to the ceiling required you to show a series of vertical arrows depicting the motion of the wad as it rose toward the ceiling. Since the arrows indicate the velocity, each arrow should be vertical and smaller than the one below it since the wad is slowing down at the rate of 10 m/s for each second. Similarly the successively higher points would become closer together as the wad slows down.

If you can't resist the temptation to come up with numerical results take a look at these: For 37 we have vi and a and displacement so the answer is

square root (2 a displ+ vi^2) = sqrt(2(-10)(-10)+0) = 14.1 m/s

For 40 we have delta t = [+sqrt (2(-10)(3) +100)-10]/-10 = .37 sec or there abouts.

General Information on How to do Physics and other sciences.

I believe that the scientific method begins with intelligent observation of physical phenomena. For a hypothesis to be accepted as true it must be tested physically. Mathematical derivations, elegant logic, strong convictions are not enough. Nature has the final say.

Homework

Homework must be done on time. At this time in the Honors class homework needs to be turned in every day by everyone, just like AP only more so since we are still focusing on ideas and analysis. In addition, class work missed on Friday must be made up and turned in. The classwork material was posted on Friday's blog.

Physics and Science Research Club

I am sure you all know by now that all the really cool people in Ridge belong to the Physics Club. How do you qualify? By being interested in physics or by having read this blog. Pretty tough huh?

We meet every Thursday that is a normal school day at 7:05 AM in Room 506 ( that's my room in case you've forgotten.) We even have bagels most meetings.

Also

The Science Research Club

is having its first meeting,
this Thursday evening, (Sep. 16th)
in room 301,
6:30 - 7:30 pm.

For all students who may be interested in pursuing independent research and entering competitions.

This is an informational meeting, and all are welcome.
Ms. Kaltenbach and Ms. Eck

AP Homework

Since we did the free fall as a demo you do not have to complete any lab tonight....but I'll get you next time.

Honors Lab Sheets

Make sure you pick up the lab sheet for the torque lab from the small table at the door first thing tomorrow.

Honors Assignment and Last problem from Friday's worksheet

Your assignment is shown on your schedule. When I ask how far the first book can stick out, I mean the following: Assume the books project over the left edge of the table and each book projects to the left of the book below it. Tell me how far the left edge of the top book projects to the left from the table's left edge. This is simply the sum of x1 + x2+ x3 +x4...........etc. Assume all teh weight of the books above Book N is applied at the left edge of Book N.

You really should try hard to get this. I don't care so much that you get the right number, but I do want you to exercise those gray cells that have been sleeping for ten weeks ( or maybe 16 years).

Read through the notes again ( or for the first time) they will help.

To solve the last problem on the balance worksheet from Friday required that you realized that weight of the ruler can be assumed to act at the 50 com mark, i.e. the middle. Then apply our rule for balancing the weight of the 100g mass times its distance from balance point must = the weight of the 200 g ruler times its distance from the balance point. Thus the balance point must be twice as far from the 100 g mass as it is from the 50 cm mark. How do you divide the distance between two point so that one part is twice as large as the other. You divide it into thirds andthe larger part is 2/3 of the total and the smaller part is 1/3. This gives you a 2 to 1 ratio between the larger and smaller parts.

Since the the weight is at 30 cm, the balance point must 2/3 x (50 cm - 30 cm) from the 100g mass, and 1/3 x (50cm-30cm) from the 50 cm mark. Thus the balance point is at 6.7 cm from 50 or the 43.3cm mark.

AP Summer Assignment Solutions

Here are PDFs of my hand written solutions. There may be a careless error or two so be a bit careful.

http://h1.ripway.com/DrCherdack/AP%2009%20SummrSlns.PDF

Honors and AP Worksheets

If you missed school today here are the worksheets that should be done by Monday. Two for Honors ( Intro to physics and Balancing) and one on motion for AP.

Have a good weekend.


http://h1.ripway.com/DrCherdack/AP%201D%20WS1.doc

http://h1.ripway.com/DrCherdack/BalancingWS1.doc


http://h1.ripway.com/DrCherdack/Introduction%20to%20Physics%20WS%201.doc

Honors Books and Numbers

If you did not enter your text book number on a sheet for me today, remember to bring in your number, not the book, tomorrow. If you left your book in school, bring it to class, we can make some use of it tomorrow.

First Day

1) If you got this far then you know the address is drcphysics.blogspot.com; the s in physics was lost for part of the day. Please spread the word to your friends in my classes.

2) If you did not get a student information sheet to fill out, here is a link to it. You can use this, or pick up a hard copy tomorrow. It must be in by Monday but sooner, like tomorrow, would be much better.


http://h1.ripway.com/DrCherdack/Student%20Information%20Form%202010.doc

3) Hope you found your first day not too painful

4) AP guys (guys has no gender connotation in my classes) make sure bring in your summer assignment tomorrow. We will be moving quickly on this topic.

5) Reminder one - No lab this week

6) Reminder two - I will be out Friday ( what a break!....................... for you or for me?)

AP Welcome and Assignment

Welcome to my blog. This is how I will communicate with you outside of class for the most part. Please check this blog at least once a day. I will try to get things posted by 6 PM but sometimes postings will be later. In any case if it goes up by 6 you should make sure you know about it and act on it , if required, by class the next day. New assignments, corrections, discussions about labs, announcements about quizzes and tests, discussions about topics in physics, notices about grade postings, etc. will all be found here. Also, if you haven't checked the blog for a few days, go back and read earlier postings.

I have a feeling that this is going to be a really good year and that we will get a lot done and have a good time doing it.

Here is the current schedule and the course guide. Make sure you and your folks read the course guide and sign the last page. Bring the signed last page in and place in your class IN Folder.


http://h1.ripway.com/DrCherdack/APUnit1Sched10-11r1.doc

http://h1.ripway.com/DrCherdack/Course%20Guide%20AP%20I2010-11.doc

Honors Welcome

Welcome to my blog. This is how I will communicate with you outside of class for the most part. Please check this blog at least once a day. I will try to get things posted by 6 PM but sometimes postings will be later. In any case if it goes up by 6 you should make sure you know about it and act on it , if required, by class the next day. New assignments, corrections, announcements about quizzes and tests, discussions about labs and topics in physics, notices about grade postings, etc. will all be found here. Also, if you haven't checked the blog for a few days, go back and read earlier postings.

I am looking forward to working with you folks this year. We should get a lot done and you will have a lot to say about what we study. I think we can accomplish a lot and enjoy the year.

Here is the current schedule of assignments and the material you will need to complete them including the course guide. Make sure you and your folks read the course guide and sign the last page. Bring the signed last page in and place in your class In Folder.

http://h1.ripway.com/DrCherdack/HonorsUnit1Sched10-11R1.doc

http://h1.ripway.com/DrCherdack/Course%20Guide%20H%202010-11.doc

http://h1.ripway.com/DrCherdack/Introduction%20to%20physics.doc

http://h1.ripway.com/DrCherdack/Notes%20on%20BalancingA.doc Note that you don't have to complete the Balancing Notes until Tuesday, especially that last problems; but you must have read through most of them by Friday.