Definitely Kaplan's physics section was discouraging. But the real physics on the OAT was much more straight forward. Only good thing about the Kaplan one is that it over prepares you so it seems relatively easier on the actual OAT. I think I did do the ADA exam last but it's kind of difficult to try to simulate the timing and computer experience. I honestly just took each section one at a time without timing it just cause for me I thought it was tedious to try to simulate it. I just treated the ADA exam as more practice problems instead.
Also, don't get too caught up on what you get on Kaplan. Just focus on improving and you should be good on the real deal! If you're curious about what I got on the Kaplan vs Real OAT:
Kaplan 1&2: 320-TS, 310-AA
Real OAT: 360-TS, 340-AA
Think my ADA exam score was similar to what I actually got on the OAT