For Physics, memorize formulas or derive them?

<p>For those who did well on Physics... as you were taking the test, were you regurgitating memorized formulas, or did you just derive the answer in your head if you already knew calculus?</p>

<p>Because the whole mechanics/kinematics section is basically calculus, aka Velocity=(Position)'; Acceleration=(Velocity)'</p>

<p>so seeing as you only have about 45 seconds per question, is it faster/more efficient to memorize the Big 5, or is that just a waste of time if you have an intuitive understanding of calculus?</p>

<p>calculus really helps
i just did what you said, derive some, but not all formulas on the spot
i got a 790 :/ but that was due to reading the question errors (several of them)</p>

<p>Just memorize them. I know how to derive them with calculus, and that knowledge will help, but not for solving certain types of problems.</p>

<p>I ran out of time for the last few (still got an 800), so time is of the essence!</p>

<p>Derive. Definitely. Memorization might get you a couple of answers faster, no doubt, but in the long run, derivations help a lot. What happens when you have to do something you've never seen before? The one who derives equations will be able to *figure it out <a href="physics=logic">/I</a>, whereas the one who memorizes will be stuck.</p>

<p>Knowing how to derive is helpful, but memorization is much faster in most cases.</p>

<p>Regarding lolcats's ideas on memorization: I agree with the above post. But I would still maintain that on a fundamental basis, derivation precludes memorization. While I have "memorized" certain formulas per se, it is only as a result of logical derivations. For example: vf = vo + at is one that I can spit out off the top of my head, but that's only because I recognize that it comes directly from the definition of acceleration, a = dv/dt. Another: integrate the previous one wrt time to get x = xo + vo<em>t + 1/2</em>at^2. This is a simple example, but the fact that these such direct links are readily apparent is the reason that "memorization" becomes more of an intuitive nature of understanding once the derivations have been done. Now my point would then go back to my original post: derive, not because it helps you memorize (although that will probably happen), but because it will help you understand and be able to come up with your own techniques when you come across the unfamiliar problems that are not like the rote examples that you have practiced.</p>

<p>Do they provide any formulas for the kids when sitting the test?</p>

<p>No they don't!</p>

<p>I think deriving or studying a derivation can be very useful in order to learn and understand the concepts (and as you get into more advanced physics there really isn't any other way). But, at the physics subject test level, I think you really do have to memorize some formulas, you just can't afford the time. For an extreme example, I think you'd rather just memorize the thin lens formula than derive it. A better example is: v<em>ave = 0.5 ( v</em>i + v_f ) ... you'll learn and understand a lot if you can derive this while you're studying, but for test day I think you should be able to write it down right away.</p>