The listed required textbook for Ph 1b Prac is Serway & Jewett, Physics for Scientists and Engineers [with Modern Physics], Volume 2. If you buy it new, you'll probably be getting the 8th edition. And that is the edition to which the Ph 1b Prac homework assignments will refer. The biggest change from the 7th is that many of the problems have been written up a little more clearly. The numbering of the problems is different (because some new ones have been added), but the text is very similar to the 7th edition. The 6th edition text is perhaps even a little better.
While the homework problems listed on the Ph 1b Prac calendar are as they occur in the 8th edition, these SAME problems (albeit some worded slightly differently) are ALL in the 7th edition. A version of the Ph 1b Prac assignment calendar with the 7th edition problem numbers is here. I mention all this because used copies of the 7th edition are probably cheaper and easier to find than used copies of the 8th (which just came out last year).
Prof. Frautschi may have the problem number conversions to yet earlier editions. Note, though, that as you go back in history, there may be a few of this year's assigned problems that are not in in those yet earlier editions.
Yet another money-saving alternative that you may want to consider is that the publisher, Brooks/Cole/Cengage, offers a download and/or on-line version of the 8th edition at about half of the retail price of a new book. However, the download self-destructs and on-line access disappears after six months. (They have yet other similar offers, too.)