I think you should be fine. You go over very general physics stuff in this course so I am confident that either edition of the textbook will teach you the concepts just as well. If you're worried then you might as well borrow a friend's or something and compare the differences between the books, but I know many people in that class who regretted getting the textbook anyways so I think you'd be fine.

I also had the first edition textbook and Dr Nejat as my prof and he said both versions of the textbooks were fine although I found myself rarely using it. In reality we probably only go over like 1/3rd of it in the course and it is only helpful for understanding the biomechanic sections which were literally only 4 questions on the exam.