Hints on practice problems

I'm not sure why hints aren't working on the practice problems. Baffling.

If you're having trouble with any of them, I did work them all out this afternoon. Send me a message of some sort, and I will give you some hints of my own. Same goes for HW7 I suppose, if you're still having trouble.

Exam 3 hints

I sent one of you an email a little bit ago with exam suggestions. Here's what I said.

Draft of exam 3 formula sheet.

Here you go. Proofreading to do, and I'll check for any obvious omissions ...

You will be given any required numerical quantities (specific heats, densities, etc.) in the problems themselves.

Important announcement, re: textbooks

If you are not continuing on with PH102 this summer, I will need to get your textbooks back from you, as part of the agreement I had with the publisher.

It doesn't have to be this week - you can bring them to the exam tomorrow, give them to me later in the week, or leave them in the physics office for me (Gallalee 206). 

Grades

All grades (except the SHM lab from last week) should be up to date now. There is also a new column in Mastering Physics listing your overall grade as of right now, which includes dropping the lowest 2 homework sets and the lowest lab.

Keep in mind you have 1 homework and 1 lab yet to come, as well as one more exam.

Exam 3 practice problems / details

There are some exam 3 practice problems on Mastering Physics now. I have set it up so you can guess without penalty an unlimited number of times, and 'give up' to view the answer at any point. These are just for exam practice, they will not count toward your grade at all.

Additionally, exam 3 will have 5 problems, of which I will grade the best 4. You can bring in a formula sheet as before, and I will provide a basic formula sheet (which I will post Monday night so you can see it ahead of time, but it may be late before I get it done ...).

Monday's lab

Monday, we'll verify Boyle's law. The lab is relatively short, which will leave us time to do the post-assessment test (and still probably finish early).

Additionally, if you would, please fill out this survey from the textbook publisher. Small price to pay for free textbooks, right?

Exam 2 scores are up

Lab scores have not yet been revised, that will be done (and the last lab's scores added) later today. Tonight, I will have some practice problems for exam 3 up hopefully. The last HW set is good practice material for the exam ...

Exam 3

Exam 3 will cover:

11.2,3,5
12.6,7
13.2,3
14.4-7 (we didn't cover quite at all of 14.7 in class)
15.3

There should be practice problems later today, probably late tonight.

Also, exam 2 grades should be ready tonight sometime. It is taking longer than anticipated.

Last HW set

Your last homework set (#7) is now out, due Tuesday at midnight. It is a mix of harmonic motion, fluids, and thermodynamics/ideal gas problems. Most of it has been covered already, some of it we will just get to tomorrow. Monday we'll go over some of the harder problems in class.

Thursday's lab

Thursday, for our second-to-last lab, we'll investigate simple harmonic motion. Specifically, we will let little masses bounce on springs and measure bouncing as a function of time. If all goes well, the motion will match the theory we discussed earlier this week.

Exam 2

The exam you just took can be found here. There were two different forms, which differed really just in the ordering of problems and a few inconsequential numbers. I hope to have solutions & grades by Saturday, maybe Friday night if things go well enough ...

HW 6 SNAFU

I accidentally made the HW due at noon today instead of midnight ... stupid am and pm. As a result, I have just extended the deadline until noon tomorrow in case you need some more time.

Course Evaluations

It is nearly that time again. A message from SOI:

SOI course evaluations will be conducted for eligible Summer I session courses from June 22 - 28, 2011. Please ask your students to watch their student email account for an invitation message with complete instructions on Wednesday. Please encourage them to complete the surveys during the data collection period.

I do take evaluations seriously and try to use the feedback you provide to make things better the next time around. Completing the evaluation shouldn't take much time. Particularly since this is my first time teaching PH101, I'd appreciate the feedback - good or bad, both are useful.

I guess more to the point: my department chair and dean look at these things very carefully. I can't see them until well after final grades are submitted, and the evaluations are completely anonymous. So, whether you think good or ill of the course, you should do the evaluation and not hold back. The evaluations are one particular bit of student feedback that receives very close attention. These days, you can actually add comments on top of the numerical rankings, all the better for you to voice your opinions.

No need to do it right now - study for your exam, you have about a week, maybe this weekend you could spend 5 min on it ... but you're not wasting your time in filling out the form.

Grading update

A few more grades are in, as well as some updates.

• The problem solving competition grades are in. I grossly underestimated how seriously you would take this, so the class average was ~102% ... you win this round! In retrospect, I should have set the grading scale higher, but it was an experiment ...
• The collisions lab scores are in too.
• I updated almost all of the revised lab grades, except for a few of you, so most everything should be current now.
• Since the labs were entered as a % score (up to 100 points) and the homework as a number of points (9 to 11 points per homework set), I realized it is probably hard for you to gauge your current grade. I therefore multiplied all the homework scores by 10 to make them comparable to lab scores. Your lab average and homework average have equal weight, as do each of the exams. Keep in mind I drop the lowest 2 homeworks and the lowest single lab.
• To calculate your grade right now, drop the lowest 2 HW sets, and average the rest. Drop the lowest lab grade, average the rest. Take those two averages, and add in your exam 1 score. Divide by 3, and that's your current grade. After exam 2 scores are in, add your averages and both exam scores, and divide by 4 ... 
• If you'd rather I just tell you your grade, I have up-to-date overall grades, just ask or send me an email. So far as I can tell, MasteringPhysics does not let me put in an overall grade column to make this easier.
• Right now, the class average is a solid B. More than half of you have A's or B's at this moment. Very few of you are in any danger whatsoever of failing. After exam 2, nearly 75% of your graded work will be in.

And, to head this off ... I hope to have your second exam graded by Friday or Saturday, and will post grades as soon as they are done. 

Slides for Tuesday's lecture

Here are the slides I used during Tuesday's lecture on waves, which we'll finish up on Wednesday.

I will spell out what material related to waves will be on the last exam, but much of what we're covering is just for 'fun' because it is neat, very much a part of everyday life, and a lot of stuff you may not have noticed before. (Wait until we talk about whispering galleries.)

There is a huge tie-in with music/acoustics which we'll just touch on, and if you take PH102 later this summer we'll learn how audio electronics work. Turns out things like speakers, equalizers, and effects pedals are really not all that complicated in principle ... they are expensive for other reasons.

(Shameless plug: I had a few students construct their own amp + distortion pedal in my lab a while back. It was great fun, and they even learned something. Pictured with the guitar is Hunter Adams, who now does something completely different. You may have noticed.)

Practice problem bugfixes

There were an embarrassing number of typos in the solutions, so here are some fixes. I'm not saying I caught all of them, but a lot of the silly errors are gone at least.

It is embarrassing when I make little mistakes, since I'm supposed to know better. When you do it on the exam, it is just a point or two off since you're still learning :-)

I guess the lesson is that one should never stop practicing ... you never know it well enough that mistakes are not possible.

UPDATE: moments later, someone pointed out that on problem 4, 11 rad = 1.75 revolutions (not 5.1 rev). The linked file is fixed now.

Exam 2 formula sheet

Find a draft here. Same rules as list time - I'll provide something like this formula sheet, you can bring in one of your own with whatever you like on it.

Monday's lab

We'll investigate torque & angular acceleration, or 'rotational dynamics.'

HW6 is out

Due Wednesday before midnight. We will do a number of them in class tomorrow.

There will be two more homework sets: one due this coming Friday, one due the following Tuesday before midnight.

Tomorrow / Exam coverage

Tomorrow, we'll spend some more time on torque and cover angular momentum (Ch. 10). With what time remains, we'll start elasticity (Ch. 11). Based on the slightly-delayed schedule, I am leaving Ch. 11 material off of the upcoming exam. That means the following are fair game for exam 2:

Ch. 6.1,2

Ch. 7.2-7

Ch. 8.1-5

Ch. 9 all

Ch. 10.1-6

This also means that exam 3 will cover about the same number of sections as the previous two exams (Ch. 11-16).

Exam 2 practice problems

Some practice problems. The first few are missing solutions, I will add those later tonight. I may also add a few more problems tonight.

UPDATE: added a couple new problems, and there are now solutions to all problems. Same link above.

Practice problems for exam 2 on the way ... as well as HW6 later today.

Exam 1 solutions

Here you are.

Conceptual mechanics test

We haven't covered all the right material yet (e.g., torque, tomorrow), and some of it is actually in PH102, but here is a nice mechanical aptitude test. Some similarities to the one you took at the start of the term.

Grade revisions

I've posted the lab 5 (work-energy) grades on MasteringPhysics now, as well as changes to some earlier lab grades for those of you who asked me to have a look. Please have a careful look - be sure that your lab grade matches the one written on the report you got back, and that your grade is the same as your group mates'. Same goes for the exam grades, do check that everything seems to be correct.*

The scores from today's problem solving competition should be ready tomorrow (Thurs), and I'll post the scores by team number here for the curious. It was a bit more chaotic and slower than I had imagined (as always), but I liked that you were engaged and putting in a good effort. You can leave (anonymous) comments here if you have thoughts on the competition, particularly how to improve it or if you'd want to do it again (modulo improvements).

* I try to be very obsessive and careful, but already at this point there are 340 lab grades alone to manually enter, and typos happen. This is something you should do in all your classes, in my opinion - anyone can make a mistake, now and again, so you should keep track of your own grades as best you can to make sure nothing seems off. There is absolutely nothing wrong with asking a professor to explain their grading calculation, that level of transparency should be considered mandatory. I don't mind at all if you question my numbers, and will happily explain them, I don't want them incorrect any more than you do.**

** If you notice an error in your favor, it is your call to mention it or not. I consider it your lucky day, and a lesson that I should be more careful. I don't expect you to bring it up, and don't fault you for taking the 'bonus.' If your conscience is eating away at you, however, then by all means let me know ...***

*** As we're on the subject of grading: I will add a column to MasteringPhysics shortly listing your overall course grade. You can ask/email me at any point for a grade update, I have them already calculated at any given moment.

Lab for Wed 15 June

Here's the lab for tomorrow, verifying the equations we came up with for 1D elastic and inelastic collisions

Exam 2 is soon ...

For the next test, I'm planning to include most of the material after that covered by exam 1 up until Monday of next week. Specifically,

Ch. 6.1,2
Ch. 7.2-7
Ch. 8.1-5
Ch. 9 all
Ch. 10.1-6

The second exam will be much like the first in format. I'll try to have some practice problems out before the weekend, but doing the worked examples in the book is a very good place to start, as are the homework problems.

Wednesday's lab: problem solving 'competition'

Tomorrow, I thought we'd try a little problem solving competition. Here's a sketch of the idea. It worked pretty well when I tried it in the past.

Lab 5: work-kinetic energy

Here is the procedure; sorry for the delay. It uses the same half Atwood machine as last time, so the mechanics of the procedure are very similar.

Wednesday, we will have a team problem-solving competition, so there is no procedure you need to read. Just show up with a calculator, a notebook, and all of your cleverness.

Things

Exam 1 scores are now on Mastering Physics. The average was 81.7% with a standard deviation of 16.0%. I was pretty much happy with this ... you'll get the exams back on Wednesday.

Lab 3&4 scores are now on Mastering Physics. I have not yet adjusted scores on labs 1 & 2 for those of you that handed them back to me for regrading.

The HW4 deadline is extended through Tuesday, since I'm out of town anyway. HW5 will follow soon.

No lecture tomorrow (Mon) or Tues, but there is a lab as scheduled on Monday afternoon/evening.

Exam 1 for your reference

Here is the exam you took yesterday. I hope to have solutions & grades up this weekend. Have a good weekend!

Another tutoring possibility

This is from another undergrad physics major, Joe Murray, who is willing to do some tutoring.

FYI I'll be back in one week so any of your students who need me will be able to find me in the SPS room [next to my office] every day from probably around 10:00 onward...

More practice problems

Here are a few practice problems from another course, with solutions.

Lab grades, once more

A couple of quick notes about lab reports:

• I have asked the grader to be explicit about what he is taking off points for.
• If you are unhappy with your lab report grade(s), bring me the reports tomorrow or Friday, and I will review them myself. If I think you've been shortchanged, I'll give you some more points. 

After getting some feedback from the TAs, I think we can be a little more lenient for the first few labs, since I think a lot of you didn't realize that you had to answer any questions asked in the writeup (and we could have been much more clear about that).

From now on, though, read the writeups carefully. For example, if the writeup says something like "Plot velocity versus time, and from its slope determine the acceleration. How does it compare with the prediction of Eq. 1?" There are three graded items here: we're expecting a plot of velocity versus time, a number for the slope and a comment on how the data compare to Eq. 1.

I guess in short, if something in the writeup is phrased as a question, it is pretty much never rhetorical. This is probably confusing because textbooks do usually pose rhetorical questions.

Last thing, I will try to just make the questions in the writeups more obvious. That will not replace carefully reading the whole thing as your best ally, but it should help ... 

Exam 1 details

Exam 1 will take place this Thursday during your normally-scheduled lab period. You will have approximately 90 minutes for the exam, but we will not be really strict on the time. (more details after the fold)

Lab 1&2 grades

I've entered your lab 1 and 2 grades into the Mastering Physics gradebook for you to see. You should get those lab reports back today or tomorrow. A few thoughts:

• if the lab average is very low, I will scale it at the end of the term.
• if we ask a question in the lab writeup, it counts toward your grade
• if we ask for specific data or a plot to report, it counts toward your grade
• we do drop the lowest lab grade for the semester
• labs are worth 20% of your grade; while a merely low lab grade will not jeopardize your grade very easily, not going to the labs at all is a very bad thing.

I haven't seen the lab reports (I do not grade them myself), but I suspect some of the lower scores were due to handing in data but not answering the questions in the lab writeup. So, make sure you read the thing carefully and answer any questions asked at the beginning, along the way, or at the end ...

If you have questions about how the lab reports are graded, or feel like you lost points for something you shouldn't have, feel free to come see me. 

Circular motion

Among other things, we'll be covering circular motion tomorrow. Here's a nice applet demonstrating the relationship between velocity and acceleration in circular motion.

In fact, there are many nice simulations on PhET site, for instance, this one on circular motion. If you're having trouble with concepts, playing with some of these applets might be a good thing to try.

Exam 1 practice problem

A few practice problems. Short solutions are included at the end. A couple of them are much harder than anything I'd ask on the actual exam, but still very useful for studying ...

Draft of the exam 1 formula sheet

Here is a draft of the exam 1 formula sheet. I haven't proofread it yet, so if you find any mistakes please let me know (I will look it over tomorrow more carefully).

This sheet will be given with your exam; you are still allowed to bring in one sheet of 8.5x11in paper with your own markings of whatever sort you find useful.

UPDATE: I did not put any trig identities on the formula sheet, could be useful. I also tend to use subscript "i" and "o" interchangeably for initial quantities, but you've probably noticed that already. 

Tutoring

I've identified an undergrad physics major who is game for doing some tutoring over the summer if anyone is interested. Send me an email, and I'll forward his contact information. Don't want to put his email & phone numbers online for obvious reasons ...

HW3 problem #2

As one of you pointed out already, problem 2 on the current homework set is a bit ambiguous until you reveal the first hint. Or, as your classmate put it "[It] doesn't make sense unless you use the 1st hint. I thought it was in the air at 0.8m not on the water."

To clear up the ambiguity, I'll just give you the first hint on the problem:

Hint 1. How to approach the problem: This problem involves projectile motion. A drop of water is launched at a certain angle above the surface, and you need to calculate the initial speed required to hit the target. Note that the target is an insect floating over the surface of the water.

Today's lab ... revised

Due to a scheduling mix-up with the PH105 class, we'll do the friction lab today, and force on Wednesday.

Here is the friction lab writeup.

And you though physics was useless

... finally, putting projectile motion equations to some good use.

HW3 - projectile motion, force

Homework 3 is out. Since I was delayed in getting it assigned, it will not be due until Tuesday at midnight. It should be a bit shorter than the last one, and we will cover a number of the problems in class either Monday or Tuesday.

Monday and Tuesday we will finish our discussions on force. Monday will be finishing up Ch. 4 and starting Ch. 5, Tuesday will be finishing up Ch. 5.

Monday's lab is now ready

Here you go. I had originally posted the labs out of order; this lab for Monday is on analyzing the force in an "Atwood's machine," a simple device with two masses and a pulley. We'll go over the analysis in class as an example problem.

Monday's lab

Tomorrow, we'll do a lab on force. I hope to have the procedure posted in an hour or so, I'm afraid I'm a little behind. To make up for not having allowed much time to read it, I will go over the gist of it at the end of class tomorrow.

[Update: I had the labs out of order. We'll do friction on Wednesday, and a different lab on force on Monday.]

Don't freak out yet, it's still early ...

Some of you have been asking about how to get a little more help. Here's what I wrote to one of you, with some suggestions:

Lab 2 bugfixes

Same link as before.

I found one mistake in the introduction (equation 7 had some extra bits), and the experimental procedure is now much more detailed.

If you've already read the procedure as I posted it earlier, you may not notice anything different, since the major changes were in the step-by-step procedure that isn't relevant until you're actually in the lab anyway. So ... you don't need to re-read the whole thing, but you might want to look around Eq. 7 if that part didn't make sense before.

Intro to Lab 1 slides

Here are the slides I used in the introduction to the lab session for the afternoon session, if you'd like to review them. (I was not there for the evening session with Mr. Davidson, but his introduction was going to be very similar ...)

If we have a little time in tomorrow's lecture, I'll do a re-cap of the lab and what the main points were. Specifically, what sort of analysis techniques wil be useful later on.

Lab 2: falling objects

I've got a draft of the lab 2 procedure up now - we'll analyze the motion of a falling object and learn how to calculate best-fit trendlines (linear regression). I will probably make some minor adjustments before Thursday (complete by Wednesday evening), but the gist of it will remain the same.

If I do make any changes, the link above will remain the same - I'll just replace the file. Please have a read through at least the introduction/background before Thursday's lab session.

Also, here's a nice applet related to linear regression you might find useful in understanding the lab analysis.