I just did Physics I and II (trig based) in 8 weeks - finished a month ago. It's certainly possible, and I got A's. But I'm older, and the need to party and such is out of my system. So I'm able to focus and study a lot every day. Personally I put about 20 - 25 hours per week into studying (honest studying - not staring at my textbook daydreaming), on top of 20 hours per week of class. Studying consisted of outlining lectures, writing equations, and doing problems.
I cannot emphasize enough that the best way to succeed in Physics is to do problems - do them until your eyes bleed. Do problems until you you dream about physics. Then do some more. Every day. For hours.
I also used private tutors when needed (my school didn't have a learning center and my prof sucked at teaching). And I got a jump-start and spent about 30 hours doing problems from Schaum's Outlines series (which I highly recommend - they're self teaching books with solved solutions) BEFORE the class even started.
If you're like most people you'll find Newton's Laws problems and uniform accelerated motion problems to be the most conceptually difficult. They come at the beginning of most physics courses, so I wanted a head start - thus the 30 hours of work before the course began.
I broke my 4 - 6 hours of daily studying into chunks - an hour here, an hour there, throughout each 24 hour period. I also did more difficult problems than I knew would be on the exams, just so I could be sure I had mastered the concepts.
If you are allowed cheat sheets to write equations on for your exams, great. If not, then memorize the equations early - don't ever be in the position of needing to waste precious time the night before an exam on memorizing the equations instead of doing problems.
If you get points for doing homework and for labs - these are easy points. Make damn sure you don't miss any there so that you'll have a cushion for the exam grades. Also try to score as high as possible on the early exams, again so you have a cushion going into the final. Don't ever put yourself in a position of being forced to rock a final to save your grade.
Also if you're rusty on any of the trig or algebra - learn that before the class starts.
Physics is a largely a big test of analytical reasoning, not much memorization. If that's your strong point you'll be fine. If not you may struggle more.
I highly recommend going to the bookstore and buying Schaum's Outlines right now, and seeing if you can teach yourself to solve projectile motion problems and Newton's 2nd Law problems - this should give you an indication of whether doing this class in an accelerated pace will work for you.