I will post your final grades on blackboard - probably by Wednesday evening. I won’t officially post the grades until much later. This way you can catch a mistake in the rare chance that I make one.
done.

b
a

Here is another worked out problem.



If you have any requests for things you would like for me to show - send it to me.

http://scienceblogs.com/dotphysics/2009/07/playing-with-a-merry-go-round.php

http://scienceblogs.com/dotphysics/2009/06/awesome-merry-go-round.php

This one is not a merry go round, but still useful

http://scienceblogs.com/dotphysics/2010/03/could_cars_slow_down_the_earth.php

An example L and omega not in the same direction: http://scienceblogs.com/dotphysics/2008/12/cd-players-in-space-and-rotations-of-a-rigid-body.php

Here are some videos.

First, I should have shown this at the beginning of the semester.

http://www.youtube.com/watch?v=Um7SttlM8fI

Sorry, embedding was disabled for that video.

Second, here is a video that Durel found.



Next, this is a video of the power balance demo (in case you forgot)



And here is the demo I did in class

Hopefully this will inspire you.

http://www.wired.com/wiredscience/2011/04/the-physics-of-the-bullet-hitting-a-merry-go-round/

I made this for you. Because I care.

http://www.wired.com/wiredscience/2011/04/curling-collisions/

I really don’t know if this will help you. Well, at least I doubt it would hurt you. Anyway, this is the rough draft of a physics book that I wrote. My goal was to put together some stuff aimed at the algebra-based physics course, but it should still help you.

It is in the epub format which you can read on a kindle or the kindle app for the iphone, ipad, android or on your pc. Have fun with it.

Just Enough Physics - Rhett Allain

Here is another example.

Here is another example.



Do you find these things useful? Give me some feedback.

Career Paths the Physical Sciences

A program designed to provide high school and college students with  information on careers in physical sciences will be held on the Southeastern Louisiana University campus Friday, March 25.
            Career Paths in the Physical Sciences (CaPPS) is a half-day program that will feature several panel discussions by professionals from industry and government in physical science occupations, science professors and teachers from area institutions, and an overview on preparing for graduate school.
            Sponsored by the Southeastern Department of Chemistry and Physics, the free program will be held in the War Memorial Student Union, room 223 with registration beginning at 8 a.m. and concluding with an informal lunch.
            Debra Dolliver, associate professor of chemistry, said the program is intended primarily for college students interested in scientific careers, high school counselors and scientifically-inclined high school students.
            “We want to show students the wide range of professions and occupations they can consider with a degree in the physical sciences of chemistry or physics,” Dolliver said. “Opportunities extend far beyond a life in academics or in a scientific laboratory.”
            The program will include a lunch time exhibition with booths from institutions such as Southeastern and graduate schools at the University of New Orleans, Southern University, LSU, University of Southern Mississippi, and the University of Alabama, as well as potential employers in the region. Representatives of various Southeastern science student organizations will also be available.
            To register or for more information contact the Department of Chemistry and Physics at985-549-2160 or e-mail ddolliver@selu.edu.

Here is the worksheet for jumping.

http://www2.selu.edu/Academics/Faculty/rallain/allain/plab223/docs/JumpMinilab%20S2005.pdf

The textbook mentions photons. You might have noticed that I always referred to them as just light. So, what is the difference?

If you want some details, here are two posts for you.
Interaction between light and matter I
Interaction between light and matter II

Those are some pretty beefy posts with lots of math. Let me give you the super short version.

When ever light interacts with matter, the matter has quantized energy. This makes it LOOK like light is in bundles of energy just like a particle would be. However, the normal electromagnetic model of light can be used for almost of all of the things that you need. The deal is that because matter is quantized, light interacts in a quantizedish way.

So, the common model of the photon as a particle of light is not needed (also in many ways it is just plain wrong).

I didn’t talk about this in class, but this is some pretty cool stuff.

Development of the atomic model

Here is my answer to the question in class. The question was: how hot would the guy doing the Red Bull Stratos jump get?

http://www.wired.com/wiredscience/2010/05/how-hot-would-the-space-jumper-get/

Here is another “lecture”



So, let me know what you think about these videos. Can you see the equations well enough? Is the audio ok? Are these helpful?

Also, if there is some particular question you would like me to work on (as a video) - I do take requests.

I am going to try something. Instead of expecting you to read the book (which I still expect) and then working problems in class, I am going to have some lectures.

Here is what will be different. I will make the lectures ahead of time and put them online. You can watch them before class or you can read the text.

So, what will we do in class?

First. I will always ask for questions. If something isn’t clear - ask. We can talk about confusing things forever if you like. It seems that there are rarely questions at the beginning of class. After looking at the last test, I doubt this is because everyone already understand everything. I suspect it is because many students aren’t coming to class prepared.

Here is a picture for you

“This class stands on a knife’s edge. Stray but a little and it will fail”

Here is a video Lecture on Springs and Potential energy (from Chapter 7)

These are the equations through chapter 6.

Here is some extra stuff for you.

First, my explanation of work-energy. - http://scienceblogs.com/dotphysics/2008/10/basics-work-energy.php

And some examples
- http://www.wired.com/wiredscience/2010/12/pinewood-derby-physics/
- http://www.wired.com/wiredscience/2010/12/cooking-a-turkey-by-dropping-it/
- http://www.wired.com/wiredscience/2010/10/why-do-we-launch-rockets-from-cape-canaveral/
- http://www.wired.com/wiredscience/2010/01/xkcd-and-gravity-wells/

And some practice problems:
Launch speed of a rocket
Earth to Jupiter space probe
Speed of a roller coaster

I am going to use some of these in class.

- Motion of an airplane
- A centrifuge
- A girl sliding down a slide

Another problem.

Suppose you want to modify the exit ramp from I-55 North to I-12 West. Here is a picture of that intersection.


According to google maps, this off ramp has a diameter of about 117 meters.
a. If the average coefficient of static friction between tires and the road is 0.3, what is the maximum safe speed a car could navigate this ramp?
b. What if the ramp is banked at an angle of 15 degrees? How will this change your answer (or will it)\

Here are some practice questions for you. These are all from HighPoint University’s Matter and Interactions page.

- Change in momentum of the Earth during one day
- Impulse on a scattered alpha particle
- Change in momentum of the Earth after colliding with a ball
- Gravitational field and weight of an astronaut in space
- Gravitational force on a planet
- A 2D lattice of balls and springs

That should keep you busy.

Here is that example I was looking for with the center of mass

http://www.wired.com/wiredscience/2010/09/bolo-toss-an-example-of-center-of-mass-motion/

I apologize for the commercial in front of the video.

Also, speaking of the moon (like we did today) - you might like this short description of how the size of the moon was first determined.

http://scienceblogs.com/dotphysics/2009/12/rp_7_cool_things_the_greeks_di.php

These are the equations I will give you for chapter 1 and 2.

This was announced in class, but I am saying it again.

On the next test, there will be 5 questions, not 4. You will only be graded on the 4 you choose though. The 5th question will be one about numerical calculations in vpython (so you can consider it to be optional).

To get you started with vpython, first go to

http://vpython.org

And download both python and vpython.

Next, I would work on the vpython assignments in webassign.

Also, you could do these (essentially the same)

VPython Labs


And here is some more info on numerical calculations:
http://scienceblogs.com/dotphysics/2008/10/basics-numerical-calculations.php 

Here is something I wrote about vectors. Maybe you will find it useful.

Vectors and Vector Addition

I posted chapter 1 practice problem in blackboard.

This is for you. At the end of last semester, I had the PHYS 221 students write some things that they would thought would be helpful for you.

Check it out.

Student Advice to Future Students (but from the past)

There are a whole bunch of old announcements on this page. I am leaving them there. They are from the previous semester. Maybe you will find some of them useful.

Here you go.

This is one cross product applet I found

http://chair.pa.msu.edu/applets/vector/a.htm

Oh - and here is more stuff on the right hand rule:

http://scienceblogs.com/dotphysics/2010/07/right_hand_rule_dont_hurt_your.php

I know you can’t be away from physics for too long. Neither can I. We will just have to make do. Here are some things for you to look at:

- Could cars be used to slow down the rotation of the Earth?
- Here is the spinning wheel demo I did in class - with explanations
- If you did this on a merry-go-round, you would probably hurl (here ‘hurl’ means to vomit)
- Balancing sticks on your hand - use a longer stick to make it easier
- Torque balls in the game Fantastic Contraption

There you go. That should keep you busy.

You know I hate Blackboard, right? I told you that. I hate Blackboard and Blackboard hates me.

Despite that, I posted your test 4 grades on Blackboard. I did it because I care.

Here is a link to that video I mentioned today in class

http://scienceblogs.com/dotphysics/2010/02/an_example_of_two_collisions.php

Oh - it includes an explanation also.

As a bonus, here is a center of mass video (with explanation also)

http://scienceblogs.com/dotphysics/2009/02/friction-demo-with-a-meterstick.php

Due to popular demand, I put a couple of chapter 9 practice questions on blackboard. Ask me in class if you have any questions about them.

I will also give you some constants

Here is the worksheet we are using in class today

http://www2.selu.edu/Academics/Faculty/rallain/allain/plab223/docs/JumpMinilab%20S2005.pdf

I am assuming that chapter 9 will not be on the next test. If that is the case, then these are your equations.

Someone needs to calculate and see if this is correct.

Hopefully you have read chapter 6 and 7. Hopefully you have worked on the homework. If you have not used WebAssign, try doing Quiz 7 and 8 from http://acme.highpoint.edu/~atitus/phy221/quizzes/index.html (good stuff).

Also, I posted in Blackboard an extra problem. On Wednesday, I am going to start on Chapter 8 unless you have questions about this stuff. Hopefully, you will ask something or I will assume this material is too easy.

The grades for test 2 were not so great. I have posted them on Blackboard. Perhaps this graph tells the story:

I was wrong. The SPS meeting will be Monday (October 4) at 12:30 in SBA 233.

Just about every Friday, there is a Chemistry and Physics Department sponsored seminar at 2:00 in Pursley Hall 211.

This Friday, I will be giving the seminar with the title: R2-D2, Beacon of Gondor, Red Bull and Physics. I already showed you some of the R2-D2 stuff, but you might like the rest too.

Here is the full seminar schedule.

Do you know what the Society of Physics Students even is (SPS)? You should. They are having their first meeting on Monday October 4th in Pursley Hall room 105 at 12:30.

What do they do? Physics stuff, fun stuff. Do you have to be a physics major? No.

Here are some great quizzes (from someone else). These would be a great way to get some extra practice:

- http://acme.highpoint.edu/~atitus/phy221/quizzes/index.html

Here is some stuff I wrote some time ago that you might like if you want to consider the difference between centrifugal and centripetal forces:

- http://scienceblogs.com/dotphysics/2009/02/centripetal-force-centrifugal-force-whats-the-deal/
- http://scienceblogs.com/dotphysics/2008/10/fake-vs-real-forces/
- http://scienceblogs.com/dotphysics/2010/01/rp_11_when_the_centrifugal_for.php
- http://scienceblogs.com/dotphysics/2009/03/fake-forces-sometimes-they-are-fantastic/

There, that should keep you busy for a while.

Although we are mostly finished with Chapter 5, chapter 6 will not be on the test.

Norman Higginbotham ScholarshipJ. E. and Mattye Lou Martin Scholarship

The Department of Chemistry and Physics at Southeastern Louisiana University is pleased to announce that it is accepting applications for the Norman Higginbotham Scholarship in recognition of Dr. Norman Higginbotham, formerly Professor of Physics and Head of the Department of Chemistry and Physics and the J. E. and Mattye Lou Martin Scholarship in memory of Mr. J. E. Martin, formerly Associate Professor of Physics.  The scholarships will be awarded to degree-seeking physics majors.  The recipients of the scholarships will be chosen by a committee consisting of all tenured physics faculty. 
 
The scholarship shall be awarded to a degree-seeking physics major.
 
The minimum requirements are
i)              A cumulative GPA of 3.0(Higginbotham) and a GPA of 3.0 in all physics courses.
ii)             (Higginbotham) Completion of at least PHYS 221/222/223/224.
iii)            (Martin)  Good moral character
 
Other criteria that will be taken into account are
i)              Academic performance.
ii)             Interest in physics as a career.
iii)            Financial need.
iv)           Involvement in physics outside of the classroom.
 
All students who wish to be considered for the scholarship must submit an application.  The application shall consist of the following information:
i)              Personal information (Name, contact information, w#).
ii)             Academic information (overall GPA, physics GPA, copy of transcripts to date).
iii)            An essay that addresses the following points:  your career plans, why you are majoring in physics, what about physics interests you, why you feel that you deserve this scholarship, and (Martin) your moral character.
iv)           Information supporting financial need (if applicable).
 
Applications will be accepted until October 15, 2010, and a decision will be made by October 29, 2010.  Please submit your completed application to the Department office in Pursley Hall 210.

First, I posted those two problems on blackboard.

Second, here is the presentation from class (Prezi.com)

x12, p14, p15, p18, x22, x23, x25, x34, x40, p51, p56, p57, p56, p67

Here is a quick derivation of change in momentum with time due to circular moiton

http://scienceblogs.com/dotphysics/2009/07/basics-centripetal-acceleration.php

x22, x24, x25, x28, x29, x30, x41, p48, p49, p53, x57, x60, x76, p81, p83,x86

So, I posted some more vpython assignments on webassign. Also, I will post the pdf instructions in the documents section of blackboard. One more thing, there are some instructional videos at:

http://www.youtube.com/vpythonvideos

Like I said in class, happy g-day (or better Happy magnitude-of-the-local-earth-gravitational-field day). Don’t celebrate too much, you still have the test on Friday.

In case you didn’t get to see my demo, I have it online (with explanations).

http://scienceblogs.com/dotphysics/2010/09/happy_g_day.php

Chapter 3:

x31, p35, p36, x38, p43, p44, x47, p51, p63, p67, p72,

Since the test is coming up, I figured I would just go ahead and post the solution to the problem from Friday - that way we can spend more time in class on other stuff.

(oh - remember, I posted the actual question on blackboard)

First, here is my sketch of the path:



This is because the gravitational force on the spacecraft will be towards Mathilde - that will also be the direction of the change in momentum of the spacecraft.

b) To estimate the change in momentum, I need two things. I need an estimate for the gravitational force and an estimate for the time the force is applied. Both of these are estimates - the problem is that the gravitational force changes as the position with respect to the asteroid changes. I am going to assume that space craft is interacting with the asteroid for about 1200 km as it passes 1200 km away from it. Again - total estimate.

First the momentum - the initial momentum of the space craft will be (I will call the x-direction the direction of the initial momentum)


How long will it take to go pass the asteroid?



What is the gravitational force on the space craft? Well, it is going to be in the negative y direction. The magnitude will come from:


But I need to get the mass of Mathilde. The mass will be:



This gives a force of:


Now using the momentum principle, I can find the final momentum of:




For the deflection, let me just look at the y-direction. Also, let me assume the average y-velocity is the final velocity/2 (because the initial velocity was zero)



Note - I had to divide by 805 because I needed the velocity, not the momentum.

Now I can use the update position formula (just in the y-direction)



A final note. What if you assumed the interaction would last twice as long? You would still get an extremely small deflection.

These are the equations I will give you for chapter 3:

I posted the question from today’s class in the documents section of blackboard.

First, just to be clear: when I say “numerical calculations”, I mean calculating something by breaking it into small parts (like with VPython).

Second, here is some more useful tutorials on numerical calculations (you don’t just have to use python).

Numerical Calculations

Springs and Numerical Calculations (essentially what I did in class)

Actually, I wrote a whole bunch of other stuff. I don’t know if you will find it useful, but here is some of the topics I have written about so far.

Introductory Physics Topics

So, I did it. I put an assignment in WebAssign for VPython stuff. Consider this stuff optional but recommended. I will talk about this some more in class - because it’s awesome.

Here is some more info on python.

If you are interested, you can install all the python and visual stuff - instructions at http://vpython.org

Also, in the past, I have put numerical questions on the test (as optional questions). Not sure if I will do this - but there is a good chance I will. Basically, there will be 5 questions on the test instead of 4. You pick which 4 you want to answer. One of these will be a numerical question. A sample numerical question could:

- have you write a sample program to calculate something (I would grade it on ideas - not on syntax)
- predict the output of a sample program
- evaluate a sample program - (why won’t this program work)
- fill in the missing parts of a program

If you want to practice, I have sample vpython labs that you can do on your own (ask me if you need help).

This is just like (but different) from the demo program I showed in class on Monday.

Chapter 2 Suggested non-WebAssign problems:

x.27, x.32, x.33, x.35, p.38, p.41, x.44, x.46, x.53, x.54, p.57, p.58, p.60, p.63,

Here are some suggestions for homework if you are not on WebAssign.

Chapter 1:
x.68, x.70, x.74, x.79, p.89, x.93, p.97, x.102, x.114, x.115

So, I told you about this online version of the demo program I showed in class.

Motion game from PHET - to make it like the demo in class, set the simulator on "a" for acceleration. This is just like force.

Here is a similar game in scratch. -
Learn more about this project

If you are having problems with WebAssign regarding access codes - I am sorry, but I have no clue in this area.

Your best bet would be to look at the student support page for WebAssign:

http://webassign.net/user_support/student/

I mentioned that I am interested in doing something different - online speaking. Does anyone have any ideas about online office hours or maybe a class wiki or something? Just let me know.

Ok, I have uploaded homework for chapters 2 and 3 to webassign.

If you are planning on not paying for webassign, go ahead and download these assignments so you can do them later. Maybe this week I will post the equivalent homework questions here.

So, if you can’t get into WebAssign - make sure you go through BlackBoard. There should be a WebAssign link under tools or something. This will automatically log you into WebAssign.

Just to be clear - you should read chapter 1. If you are finished with that, start chapter 2.

I will put up the chapter 2 homework very soon. On Monday, we will finish up chapter 1.

A couple of things:

1. Webassign. Remember it is free for the first 2 weeks or something like that. You don’t have to buy it if you don’t like it. After 2 weeks, I will post some homework questions for those that aren’t using it.

2. You can get to webassign through blackboard (I think it is under “tools”)

3. Start reading the textbook.