For the physics, I literally just watched Chad's Videos and did the quizzes and at the same time read the Kaplan book and did the questions after watching Chad's videos. His videos for physics makes things much clearer which made reading and answering the Kaplan book doable. If you want questions that are pretty representative to the real OAT, then look at this link:
Physics
Create a free account and scroll all the way down pass the Physics Test portion and you'll have access to the free practice problems for each of the physics subjects that potentially will be tested. Doing these problems is what helped me the most. It's a lot, but it's very doable and similar to the real OAT. And the Kaplan physics is definitely harder than the real deal. The real OAT for physics it's straight forward and you're not doing like 3 -4 step calculations. Mostly 1-2 at the most and it's like main formulas like kinematics and such. Half conceptual and calculation based. Good luck!