It depends what physics you're testing out of. Are you testing out of regular high school physics, honors physics, AP physics B or AP physics C?
I recommend you take the physics AP exam (b or c depending on your studies) to demonstrate your knowledge in physics. IMO, "testing out" based on loose high school criteria doesn't say much about your aptitude in the area.
Regular high school physics. My school has prerequisites for taking science classes. I took regular biology freshman year and I'm in general chemistry as a sophomore. I wanted to test out of regular physics so I could get out of the prerequisite for a future AP Physics class.
Idk if it's a good or bad idea honesty (in relation to college apps) but just go to a used book store or Barnes and nobles and find a book you like and buy it for cheaper on eBay or amazon. Beginning concepts are pretty easy to understand (movement-air pressure so far), but I'm sure heat and water and electricity get tricky so I might seek some help with those subjects.
