Applied Maths Equations

I'm teaching myself applied maths, and the only part of it that's causing me any confusion is knowing what formulae I need to derive and which ones are ok to produce out of hat.

How do I know which ones have to be derived before use? I know the range and max height formulae for projectiles must be derived. But, what about equations for simple harmoic motion or centripetal acceleration etc. Is it ok to produce them without derivation, unless it specifically asks for the derivation? I've no teacher to ask as I'm teaching myself! If anyone could clarify things a tiny bit I'd appreciate it.

Thanks.

timmywex

i suggest you look up the sylabus, itd be on the ncca website, i though only the linear motion equations had to be derived, but sure im learning something here too! Chances are proofs wont be asked at hl anyways, if you are doing higher level

Thanks for the reply timmywex.

See, my problem isn't in learning derivations and proofs etc. It's knowing when you can produce an equation out of hat, as opposed to deriving it. For example, when doing a question on SHM or Circular Motion, and it doesn't say to derive the formulae before using them, can you just produce them off the top of your head? Or is it more like the Range and Max Height formulae in Projectiles, do you have to derive all formula before you use them?

That's where my confusion lies!

MathsManiac

I would say the best place to seek guidance is in the marking schemes at the SEC website. If you're not sure about a particular equation, find the last time a question appeared that required it, then look up the marking scheme. If the solution in the marking scheme pulls it out of thin air, then so can you.

Unless specifically asked to prove it, it would be safe to use any formula from the tables, but certain other ones are ok too, I think. My guess is that the SHM ones are ok, but I suggest you check the schemes.

Thanks for your reply MathsManiac. Yah, I guess that's the best thing to do. I'll have a look through them now to see. I guess it's not the biggest problem in the world, but, I just wouldn't like to lose marks over something so small!

On a kind of related question. In applied maths, are you limited in the methods you can use to solve problems or derive formulae? Do you have to use the methods that are shown in the text books? Or is it more like physics, in that you can use whatever method you know of, as long as it's a genuine method and it produces the correct answer? For example, would you be allowed to, say, use Euler's formula as a method to derive the SHM formula? Or are you confined to deriving it the way it's shown in the text book. If you get my drift.

Peleus

use any method you like as long as it get the right answer in the right way.

PurpleFistMixer

They'd get uppity if you pulled an obscure formula from nowhere and started proving things with it, I'd say. Like, you've probably derived the formula that gives the range of a projectile in terms of the angles etc., but you wouldn't be allowed to just use that out and out in the exam, you'd have to prove it first. So in that regard it'd seem like there's a set number of equations you're allowed to work with. However, they DO give out awards for the most elegant solutions, so that'd suggest a degree of freedom. : p You're not confined to the precise method in the book, anyway, hell we only used the book for questions in my class so I don't even know what method the book has in it... You could probably quite happily go about doing everything using calculus if you wanted (you will in college!)...