I’ve been studying for the SAT physics subject test this summer and went through all the PR chapters to cover the holes in my knowledge (pretty much all of the magnetism and optics stuff as well as modern physics). I was wondering if I had to memorize literally every formula including the special relativistic stuff. I searched this question and I’ve seen several conflicting answers. Some say advanced formulas are very rarely needed/used while others say it’s important to memorize all of these: chrome-extension://klbibkeccnjlkjkiokjodocebajanakg/suspended.html#uri=http://www.erikthered.com/tutor/facts-and-formulas-3-ref.pdf
Is it necessary? I can either way but I just don’t want to have to focus on constantly keeping any unnecessary formulas in my memory when I could be focusing on application of the concepts instead. I have pretty much all of the “typical” formulas memorized like the Big Five, the basic electricity ones, etc. But are all of those weird formulas and the E&M ones necessary to know too?
I would say you don’t need to completely memorise the formulae but you do need to know the relationships between the variables (e.g. is it an inverse square law, are they positively/negatively correlated?). Many questions will ask you what happens to one variable if you change another (e.g. what happens to gravitational force if you increase distance by a factor of 2), so knowing the relationships is important. With the special relativity stuff, I think this is a case of knowing whether something gets bigger/smaller, so know whether a length will appear shorter or longer in different situations, whether time will slow down or speed up in different situations etc. What you definitely do not need to know is the value of the constants (e.g. G) - these are provided if, on the off chance, you actually need them. Remember they can’t ask you to do particularly complicated calculations since you need to answer something like 85 questions in 60 minutes without a calculator. Also the curve in Physics is pretty sweet - so don’t worry about knowing exactly how to do every single question. Hope this helps! (For the record I got an 800 in the Physics Subject Test and I’m just speaking from personal experience.)