About Homework (Spring 2005)

Weekly homework assignments (See HWAssignments for details and due dates) are due in class on each Wednesday (or on Friday if Wednesday is an Exam day). They consist of ``Conceptual Questions'' (designated by CQ) and ``Exercises'' (designated by ``Ex'').

For Physics 117, HW is a necessary learning experience: in physics, the ability to quantify one’s knowledge in the form of computations is essential. The HW exercises quantify the physics you have learned. In addition, once the answer to a problem is obtained as an algebraic expression (as it should always be obtained before your insertion at the last stage of the relevant values of the numerical parameters to obtain your numerical result), it becomes a tool for generating physical intuition by considering how the result might change for other values of the parameters (and especially extremely large or extremely small values, where phenomena often exhibit especially clear and simple behavior), or by asking oneself “what if?” questions: What if x had been given and a, b, or c, required, instead of the other way around? Exploited in this way, HW problems can qualitatively enhance one’s physical intuition, which helps immensely in coping efficiently with the course exams.

Check Your Own Homework

We shall generally assign odd numbered HW problems, so that you can readily check your answers which the text provides in its Appendix A. (Be aware that textbook answers are wrong with surprising frequency. If you think an answer you obtained is correct and the text’s is wrong, check further….you may very well be right.)

We shall post the solutions to the HW problems on our 117 course website a week or more before the assignment is due . Go to <http://www.physics.umd.edu/Academics/Courses/Physics117(Griffin)>  and click on Check Recent Announcements. There you will find a lin to each HW solution set posted. You are encouraged to work ahead of the HW due dates: This allows you to identify sticking points early and clarify them when they arise in lecture. It also gives you the opportunity to set your work aside and then to return to it for a review before it has to be submitted.

If at first a problem baffles you, re-check the text to see what you missed. Then look at the full solution to see whether that helps to clarify things. If it does not, you need to talk to someone about it. Look for help. Other students are often the most immediately available (e.g. in the hall before lecture) source of help, but do not hesitate to ask the TA or the professor, and sooner rather than later. (Both announce and keep office hours specifically to invite questions and discussion of sticking points.) HW Confusion left unsettled undercuts the basis for the next stage of learning and generates more confusion. When you are finished your homework, check your solutions against those posted on the website to see whether any fine point eluded you.

HW Grading

The homework will be graded and returned each week. The grading, however, will be only partial, due to the limited TA time available for this task. Generally we shall grade one problem fully in each set (generally 10 problems) for 3 points and add an additional point for each of the other problems for which an apparent good faith effort at solution was made. Thus each 10 problem HW set will typically carry a maximum grade of 3+9*1=12. Note that the answer alone is not a good faith effort at a solution. That much is listed by the text book. Even if the problem seems trivial, show that you understand where the answer comes from.

The task of the HW is to learn how to do the problems, and you should use all of the means available to you to do so. But in the end, having learned what you needed to know, you should write your own HW solutions from your own knowledge. Clearly there is no way to prevent a student’s simply copying the HW solutions as posted and handing them in as his own. But we believe that is a self-destructive strategy, because the skills left unacquired thereby will drag down one’s test scores disproportionately.

On the due day, place your homework solutions in the trays at the front of the lecture room just before or just after class, -not during class time). Please staple the pages together (using the stapler in the pick-up trays, if necessary) and put your name and lab time (e.g. "Thu 4PM") on every page.

Homework not submitted in class will be considered on time if placed under the door to Physics Room 2109 on the due date, i.e. before 12:00 Midnight. (But note that delayed lab reports must be placed in the Physics 117 Lab Mail Slot in the wall near Physics Room 3316; please do not submit lab reports at any location other than the Lab Mail Slot.) Late homework will not be accepted. If you must be away on a homework due date, turn in your homework early. Missing one or two HW’s can be penalty-free under the 80% rule discussed below which is designed to allow you a miss or two for illness or other reasons, albeit with a corresponding reduction in your flexibility . But if some set of ongoing or recurring difficulties repeatedly prevents your submitting the HW on time, then the matter should be discussed with Dr Griffin.

Note that overall HW (and Lab) grades will be determined on the ``80% is Enough'' basis: everyone who gets 80% or more of the maximum possible total semester score will be given the same maximum raw grade of 100%. See the more detailed discussion under GRADING POLICY. This scheme reflects the fact that HW and LAB are learning processes where perfection is not to be expected. It can also allow for a missed HW. But note that ``80% is Enough'' places a heavy premium on achieving a full 80% on these items, since nearly everyone will do so, and those who do not may fall seriously below average after renormalization.

The assignments for the first part of the course are listed in HWAssignments.