Physics 2140, Fall '95 Homework #4

Due Wed, Sep 27

Reading for this homework: Boas Ch. 5, 6.10

Reminder: First midterm exam is Tues, Sept 26, 7:30 PM

1) Boas 6.8.15

2) Boas 6.8.16

Then (going backwards in Boas:)

3a) 6.6.17

3b) 6.6.18

4a) 6.7.1

4b) 6.7.18

The above questions cover material which is all fair game for the exam. (aind in fact those are all good review problems as well) I strongly suggest you try them before Monday 9/25, in case you have questions before the exam.

The following problems are optional , you do NOT need to turn them in, because they cover material which will not be on the 1st exam. However, in order not to get behind, I urge you to still do them. (They cover things we're doing in class today, 9/20 and Friday 9/22) If you really can't get to them before the exam, be sure to try them immediately after the exam, say by Fri Sep 29...

5a) A flat right-triangular plate ("lamina") has a mass density xy. The coordinates of the corners are (0,0), (1,0), and (1,2). Find the center of mass coordinate x(c.m.) (don't bother with y(c.m.)).

5b) Boas 5.4.2c (You may use the formula given in Boas 5.4.2a)

Hint: The position of the x component of the centroid should be "physically obvious" - so, if you see the answer, you do not have to "prove it" by doing the corresponding tedious integral

5c) Boas 5.5.3