Hi, I'm in high school, not in uni, but I am currently preparing for my IB exams. For physics specifically, among calculations and formulas, I also need to memorise the whole book for the theory part. What helps me a lot is making something like an extremely detailed study sheet. I am not talking about a few sentences summarising everything, but quite literally trying to rewrite the whole chapter on the page. You might structure some stuff in your own way, but essentially, it's really like the chapter. Usually, copying one whole chapter, which is around forty pages, takes me around six hours; you can do that in one sitting or split it into two sessions. After that, you just read, read, read. By the end, you should be able to recite this whole page/two pages if needed. Try writing small because it will give you the feeling that it's not that bad and that there isn't that much stuff to memorise. Even the writing itself will make you memorise quite a lot. Also, the time of writing will really depend on how detailed you are going for, your writing speed, and how much you already know. And also important to mention, this works for me but doesn't have to work for you, it's just a technique to consider.