<p>can someone help me how to derive some formulas? im sure it will make memorizing easier</p>
<p>k<em>i^2=U</em>((i/2)^2*M)</p>
<p>therefore k=(U<em>((i/2)^2</em>M))/(i^2)</p>
<p>k stands for kinetic bullsh * t.</p>
<p>Learning how to derive formulas is a huge waste of time for the AP physics tests. Just understand WHY formulas work, and that will help you remember them.</p>
<p>^I agree, for MC you really only need to know basic equations mgh, and F=ma, etc. The FRQ gives you the formulas.</p>
<p>Just do a lot of problems. Then choosing the correct formula becomes second nature.</p>
<p>
[QUOTE=Latency]
Learning how to derive formulas is a huge waste of time for the AP physics tests.
[/quote]
</p>
<p>Uh huh. And what do you do when you come across something you’ve never seen before? The kid who knows how to derive has an infinitely valuable skill that is extremely versatile. The kid who just “remembers” the formulas… well, she/he is out of luck. </p>
<p>
[QUOTE=Latency]
Just understand WHY formulas work
[/quote]
</p>
<p>What better way to do that than by deriving them?</p>
<p>wewet234, people are studying for a test. most of them aren’t gonna become physicists and would be happy with a 4 or 5. you might like extra unnecessary effort, or you might want to be a physicist yourself, but please remember this is AP.</p>
<p>Wewet, we understand where you are coming from but you have to understand a few things</p>
<p>1) There is a large volume of material to be covered for any given AP. The teacher does not have time in class to go over all the derivations, etc.
2) Students are pressed for time with ECs and other commitments. I don’t know about you, but that extra hour of sleep looks a lot more tempting than doing extra (and optional) work.
3) Memorizing formulas is enough to pass the AP exam
4) AP courses are not designed to give you an “end all be all” understanding of a subject. These are first year courses and obviously only grace the surface of the subject material. If you truly want a good understanding of physics, then you will take physics in college where the emphasis is on critical thinking rather than learning to a test.</p>
<p>I agree with the above posters. Even if you want to be a physcist there is no point in learning the derivations now. Wait till college comes along and you really need. AP tests are meant to be broad and comprehensive. The questions themselves are not hard, but the expansive amount of material makes it hard to get a very high score. (Not 1,2,3,4 or 5) I mean like 100/100 on MC or perfect on FRQ. Its meant so that people will miss a bunch of questions.</p>
<p>
[QUOTE=jamesford]
- There is a large volume of material to be covered for any given AP. The teacher does not have time in class to go over all the derivations, etc.
- Students are pressed for time with ECs and other commitments. I don’t know about you, but that extra hour of sleep looks a lot more tempting than doing extra (and optional) work.
- Memorizing formulas is enough to pass the AP exam
- AP courses are not designed to give you an “end all be all” understanding of a subject. These are first year courses and obviously only grace the surface of the subject material. If you truly want a good understanding of physics, then you will take physics in college where the emphasis is on critical thinking rather than learning to a test.
[/quote]
</p>
<ol>
<li>That’s why you do it yourself. Getting spoonfed by teachers defeats the purpose. </li>
<li>Everything we CC overachievers do to get into top colleges is technically “optional.” There’s a nonunique. </li>
<li>Physics and math are unique in that they are the subjects that you don’t have to be that robotic freak of nature who regurgitates facts to excel in. You’re right because you proved that you’re right, not because you think you probably remembered that formula written on the chalkboard that one day in class when the teacher was ranting. (I’d even go as far as to argue that this certainty, if you will, is precisely what makes it easier.) As for your point, sure memorization can be “enough.” But I want to quote the OP here:
[QUOTE=jpl]
can someone help me how to derive some formulas? im sure it will make memorizing easier
[/quote]
Now, think about how many formulas you’re trying to remember here. What if you get a square mixed up with a cube and it gets stuck that way in your memory (which I’m sure you’ll admit is not infallible)? Derivation is a useful technique even for memorizing. </li>
<li>and it still works well even if you don’t want to be a physicist. Plus, I think the mindset of “I’m not going to use my brain until I’m in college” is pretty silly. </li>
</ol>
<p>Advice to anyone who cares: Take at least some physics (and math) in college. It seems like there’s this general trend across high schools classes to completely neglect everything that makes physics (and math) so wonderful. </p>
<p>@jpl: If you need help on something specific, you can PM me. I’ve already taken the exam, so I could probably be of some use.</p>
<p>The thing is, I believe that learning to derive the formulas, with the knowledge of physics that a high schooler will have, is memorization in itself. It takes a lot of background and experience with physics to be able to actually derive equations without memorizing HOW to derive them (as with most derivations, the steps are not obvious). Obviously, memorizing how to derive formulas not only defeats the purpose of deriving, but also sends you 3 steps backwards because it is harder to memorize and deriving actually takes time.</p>
<p>And, as far as my knowledge goes, half of the equations in physics B (the class I’m in), are created from experiments instead of derivations from first principles. Unlike in math, in physics, there isn’t one, small, solid foundation that everything else builds off of. There are many different starting points, and all those different equations aren’t even mathematically derived in the first place.</p>
<p>I was writing under the assumption that we are talking about physics c (calculus based). At that point, much of the derivations become mathematical in nature. Sure, there’s stuff that’s based on empirical results (although I think you’re overestimating here). </p>
<p>
[QUOTE=Latency]
It takes a lot of background and experience with physics to be able to actually derive equations without memorizing HOW to derive them (as with most derivations, the steps are not obvious).
[/quote]
</p>
<p>*How do you gain “background and experience”? *</p>
<p>To a large extent, yes, it requires a bit of intuition. I agree that the way to go is not only to be able to understand how to go from step n to step n+1, but rather to be able to follow the pattern of reasoning. IMO that difference is actually not as subtle as it may seem. </p>
<p>Yeah, we’re high school kids, and there are derivations that we probably wouldn’t have so easily thought of. It’s all about what you make of it. Do you (a) look at the answer and memorize the steps, or (b) come up with general approaches by which you can attack the problem and see how well that matches the line of reasoning in the solution? I agree that (a) sends you 3 (maybe 4 or 5) steps back. On the other hand, I’d argue that (b) is the technique by which we acquire the background and experience that is so valuable. Over time, you begin to see that even if you’re wrong, you are able to identify flaws in your logic and are not only able to correct them but also able to understand the solution a lot better. It’s also important to recognize that there are MANY ways to solve a given problem, so searching for alternative derivations can also be pretty fun. When you are looking at a solution, focus not only on understanding HOW to do the mathematical manipulations but WHY they are being done in that way. </p>
<p>I hope we’ve agreed on something here.</p>
<p>@ Latency: I definitely agree. The derivations (in science anyway) are rarely obvious and memorizing how to derive formulas is just as bad as just memorizing the formulas. No one’s going to argue that simply memorizing formulas gives you a good knowledge of the subject, but that’s the way our educational system is set up. Btw, you use E = Mc^2 in AP Chem. Good luck deriving that on your own.</p>
<p>@ Wewet: we’re talking memorizing formulas here, not problem solving steps. Memorizing problem solving steps obviously gets you nowhere.</p>
<p>I agree, in essence, with what you are saying, but it seems to apply more for general problem solving than this whole derivation conflict. As you say, coming up with general approaches, understanding the logic and reasoning, and understanding how problems work is paramount to being a good problem solver. This is especially prominent in math (not really school-based math such as calculus, but for the AMC and tests like those).</p>
<p>However, I’m not sure if this really applies to derivations. The background and experience I speak of is extensive exposure to physics. This can be achieved through learning the history of physics, solving many physics problems, and just having a deep comprehension of physics and what it really consists of. Only then can one truly understand derivations to the point of not having to memorize them. I don’t believe most high schoolers have achieved that status.</p>
<p>By the way, I imagine Physics C (which I have no experience with) is more “mathematical” and derivation-based than Physics B, so our arguments might be running on parallel lines…</p>
<p>sometimes if you don’t even know formula, know what the questions asking for, for example:</p>
<p>Power = Joules/sec
Volts = Joules/Coulomb
Electric Field = Newtons/Coulomb or Volts/meter</p>
<p>knowing that may just let you get numbers and divide/multiply to get into the right units for the answer.</p>
<p>I’ve been learning how to derive some lately and it appears I can understand physics a bit deeper now. I think differently and approach problems differently. It also automatically helps with the memorizing so I recommend it if your taking a physics test.</p>