So I have said that the homework is due at the end of the day formally, i.e., 11:59pm on the day in question. That is still true. There are 'grey areas,' however.
Less formally, it will not be considered "late" if I am still awake after that time. Tonight that means you have about another hour or maybe 90 minutes. In general, 1-2am is a reasonable bet. If you're staying up until 2am doing homework, that is hardcore, and I'll give you some leeway ;-)
Minimal points are taken off for submissions arriving before I begin grading the homework, usually a day or two after the due date. Things happen, you get busy. Don't make it a habit.
Submissions after I have already posted the solutions online are taken on a case-by-case basis, but will receive some credit for at least bothering to copy the solutions. Learning by osmosis can work sometimes.
The message here is again: always turn it it. It is never given zero credit.
Showing posts with label the-prof-is-daft. Show all posts
Showing posts with label the-prof-is-daft. Show all posts
Friday, March 27, 2009
Tuesday, March 24, 2009
Tuesday's class / Gravitation
For better or worse, there will be much mathness tomorrow. Two things that can help either before or after the fact:
In the end, you will not be responsible for the derivations, only the main results. You will see the derivations again in PH301 or PH302 (and possibly MA227). The hope is to show you that the main points of Ch. 13 can be derived with a bit more work, which will ideally help you appreciate them a bit better. Also, all that scary math at the beginning of the semester will pay off again, which is nice.
Once that is out of the way, we'll work on some of the homework problems. Thursday, we will make use of our shiny new results, and be able to show that the remainder of Ch. 13 is a bunch of special cases.
Anyway: tomorrow will be a lot of 'I derive stuff not in the book and you watch' than usual, but not without good reason.
- Skim Ch. 13 of your text (gravitation)
- Remind yourself about motion on generic curved paths.
In the end, you will not be responsible for the derivations, only the main results. You will see the derivations again in PH301 or PH302 (and possibly MA227). The hope is to show you that the main points of Ch. 13 can be derived with a bit more work, which will ideally help you appreciate them a bit better. Also, all that scary math at the beginning of the semester will pay off again, which is nice.
Once that is out of the way, we'll work on some of the homework problems. Thursday, we will make use of our shiny new results, and be able to show that the remainder of Ch. 13 is a bunch of special cases.
Anyway: tomorrow will be a lot of 'I derive stuff not in the book and you watch' than usual, but not without good reason.
Wednesday, March 4, 2009
Problem 10.42
Right .... so I screwed up a unit conversion myself.
The numerical answer to 10.42a should be 8.32e-6, not 8.32e-3.
(I missed that the mass was in mg, not g ... my bad.)
The numerical answer to 10.42a should be 8.32e-6, not 8.32e-3.
(I missed that the mass was in mg, not g ... my bad.)
Friday, February 27, 2009
Recent episodes of FAIL
So, here's how it is. Thanks to weather-related FAIL today, I'm stuck in Miami for another day. I had hoped to get back late tonight, go grab the exams tomorrow morning, and have them graded and back by Tuesday.
At the earliest, I'll now be back in town Saturday afternoon. If all goes well, I can still get the exams graded by Tuesday ... I will try. At the very least, I will get you solutions to the exam by Tuesday, one way or another. I really did choose all the problems there for a reason, and I want you to see how they are worked out while the ideas are still fresh in your mind.
At the earliest, I'll now be back in town Saturday afternoon. If all goes well, I can still get the exams graded by Tuesday ... I will try. At the very least, I will get you solutions to the exam by Tuesday, one way or another. I really did choose all the problems there for a reason, and I want you to see how they are worked out while the ideas are still fresh in your mind.
Sunday, February 22, 2009
HW 5 solutions
The solutions to Homework 5 are out.
Just for 'fun,' I included code snippets in various languages to solve the last problem, in which you needed to sum the harmonic series over 75 terms. Actually, I wrote quick versions in several languages, such was the depth of my procrastination. Represented are
(In particular, my postscript solution could be fancied up quite a bit for prettier output. The bash script is also a bit cheap and approximate, since one can only use integers.)
Just for 'fun,' I included code snippets in various languages to solve the last problem, in which you needed to sum the harmonic series over 75 terms. Actually, I wrote quick versions in several languages, such was the depth of my procrastination. Represented are
- C (iterative and recursive solutions)
- Pascal
- Perl
- LISP
- Python
- Java
- shell (bash) script
- Postscript
- Fortran
(In particular, my postscript solution could be fancied up quite a bit for prettier output. The bash script is also a bit cheap and approximate, since one can only use integers.)
Thursday, January 29, 2009
Why are there so many bastard problems?
So, I don't think this will make me seem like *less* of an ogre, but I thought I'd put down some of my reasoning behind your homework sets.
The homework is really, really difficult. I won't pretend otherwise. In fact, it is comparable to what physics majors at places like MIT would see - meaning if you are getting through it, or at least understanding the solutions after the fact, you are learning physics as well as anyone anywhere.
(Your exam problems will not be as hard. Not even close. I'll post some sample problems tomorrow to give you an idea.)
Out of every (say) three problems I give you, I usually expect one of them to be pretty easy or very similar to an example problem in the book or online. A second one usually has a painful but straightforward brute-force solution, and a more mathematically sophisticated but shorter solution. Then, there is usually the bastard problem, which is just going to suck.
So why the bastard problem? One, I can't really see how much you have learned, and whether you can apply it in unfamiliar situations, if you ace all the problems. In that regard, it is OK, and expected, if you don't complete the whole thing. On the toughest problems, you will be well-rewarded for just trying something sensible, I tend to grade the 'bastard problems' pretty leniently. If you don't get those problems, you are still going to end up just fine - you will not need to solve all of them to get an "A." With the partial credit scheme based on the homework template, even just setting up the bastard problem, without solving it completely, can get you 75% partial credit.
Two, it is still very valuable if you try the problem and get stumped. There is heavy partial credit for trying, but that is not entirely the point either. If I just solve the really tough problems in class for you, without you having tried them, they will either be hard to follow or seem deceptively easy. So the theory goes, at least.
Three, for most of you it is going to 'click' at some point, particularly once we learn some new techniques in the coming weeks. Most of this week's homework can be solved in a few lines with the benefit of hindsight we'll have at that point. It is just hard in the beginning, period.
Four, you are free to (and encouraged to) collaborate. This is not a justification for making the homework difficult, but a reminder that you should help each other get through it when you can ...
Finally, part of the point is that our students often get to 300 level physics classes and get creamed. I'd rather it be reversed, at least for honors students - by the time you get to PH301, you should manhandle it.
So how do I calibrate the homework? I solved all of this week's problems on Friday night and just made a second pass to double check. If I can't do the whole homework set in about an hour, using only the same things we covered in class, it is too much.
As an aside: part of this is about time management as well. Is it OK to spend time x and get 90% credit, or should you spend time 2x to get 95%? Multiply that by 4 or 5 courses and life outside classes ... don't spend three extra hours on physics for 5% more if you can spend it on calculus for 25% more.
The homework is really, really difficult. I won't pretend otherwise. In fact, it is comparable to what physics majors at places like MIT would see - meaning if you are getting through it, or at least understanding the solutions after the fact, you are learning physics as well as anyone anywhere.
(Your exam problems will not be as hard. Not even close. I'll post some sample problems tomorrow to give you an idea.)
Out of every (say) three problems I give you, I usually expect one of them to be pretty easy or very similar to an example problem in the book or online. A second one usually has a painful but straightforward brute-force solution, and a more mathematically sophisticated but shorter solution. Then, there is usually the bastard problem, which is just going to suck.
So why the bastard problem? One, I can't really see how much you have learned, and whether you can apply it in unfamiliar situations, if you ace all the problems. In that regard, it is OK, and expected, if you don't complete the whole thing. On the toughest problems, you will be well-rewarded for just trying something sensible, I tend to grade the 'bastard problems' pretty leniently. If you don't get those problems, you are still going to end up just fine - you will not need to solve all of them to get an "A." With the partial credit scheme based on the homework template, even just setting up the bastard problem, without solving it completely, can get you 75% partial credit.
Two, it is still very valuable if you try the problem and get stumped. There is heavy partial credit for trying, but that is not entirely the point either. If I just solve the really tough problems in class for you, without you having tried them, they will either be hard to follow or seem deceptively easy. So the theory goes, at least.
Three, for most of you it is going to 'click' at some point, particularly once we learn some new techniques in the coming weeks. Most of this week's homework can be solved in a few lines with the benefit of hindsight we'll have at that point. It is just hard in the beginning, period.
Four, you are free to (and encouraged to) collaborate. This is not a justification for making the homework difficult, but a reminder that you should help each other get through it when you can ...
Finally, part of the point is that our students often get to 300 level physics classes and get creamed. I'd rather it be reversed, at least for honors students - by the time you get to PH301, you should manhandle it.
So how do I calibrate the homework? I solved all of this week's problems on Friday night and just made a second pass to double check. If I can't do the whole homework set in about an hour, using only the same things we covered in class, it is too much.
As an aside: part of this is about time management as well. Is it OK to spend time x and get 90% credit, or should you spend time 2x to get 95%? Multiply that by 4 or 5 courses and life outside classes ... don't spend three extra hours on physics for 5% more if you can spend it on calculus for 25% more.
Tuesday, January 27, 2009
And on the lighter side of physics ...
Modeling the head on a glass of beer.
By the end of the semester, we should be able to do better. Of course, we will not have an associated laboratory experiment.
By the end of the semester, we should be able to do better. Of course, we will not have an associated laboratory experiment.
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