Picking the right equation for the question,

[Philip Wong]

I'm going to have my exams in just over a weeks time. I'm honest that up to this point I don't know all my materials well enough (or know them at all) that I could automatically picked out the right equations to use for my up coming exams. and in exams situations and under extreme stress, there is no way I could check did I use the right equation for the right question (such that I gave a correct answer to give me maximum points), let alone I won't have a clue that did I start off using the right stuff at all...

Is there any tips for taking exams in physics and maths such that I could boost up my marks? (well except for doing more studies, of which I'm trying to do now...)

also does doing more practices (i.e. doing pass exams, and going over materials again) helped?

 

[fasterthanjoao]

also does doing more practices (i.e. doing pass exams, and going over materials again) helped?

Of course, doing more problems is the key to passing exams in physics. Reading the material from different sources is an option as well - as in, get yourself different textbooks on the same subject if you're struggling to understand the course notes.

Otherwise, when you start a question try to make sure the first thing you do is write down the information that the question tells you. Write the symbols and their values and, if possible, draw a diagram. Doing this can help jog your memory and even calm you down a little before you start panicking that you don't know what's going on.

 

[ATOMatt]

I always start by writing out all the quantities you are given in the question, even if it is obvious which equation to use, so that the examiner gets the feeling that you know what you are doing (even if you don't :P). If you really get stuck, look at the units of the quantities given and then at the units your answer is supposed to be in and hopefully it should become apparent which equation/equations you need to use. :)

Of course you should do a lot of practice problems leading up to your exam though, so good luck with that. :)

EDIT: Yeah I've basically just said the same as fasterthanjoao... nevermind

 

[Jack21222]

ATOMatt adds a good point about units. Dimensional analysis will take you further than you might expect.

 

[Count Iblis]

I know that many students think in terms of "how to pick the correct equation", but this is a flawed way of thinking. In fact, we do our best to make homework and exam questions in such a way that students who can only "pick the correct equations", without having a deep understanding of the topic, will fail.

You should really focus on understanding the theory from first principles. The only reason why you use an equation should be because it saves you time. It should always be the case that, had you been given enogh time, you could have derived that equation you are using yourself from first principles.

 

[Philip Wong]

I know that many students think in terms of "how to pick the correct equation", but this is a flawed way of thinking. In fact, we do our best to make homework and exam questions in such a way that students who can only "pick the correct equations", without having a deep understanding of the topic, will fail.

You should really focus on understanding the theory from first principles. The only reason why you use an equation should be because it saves you time. It should always be the case that, had you been given enough time, you could have derived that equation you are using yourself from first principles.

well in my own opinion, this really really depressing to hear...
but I couldn't argue with that, I understand what you meant and totally agree with it. well i haven't being doing physics since 6th form, and my degree in university is in psychology and applied statistics. of which in ways "neither" of them requires to work with formula much, and you can pretty much "smell" it out does your results work or not. I've only recently start taking year 1 physics again because is only until very recently (my last year of doing the degree, and 6 years since I've graduated from college) that I released I'm interested in doing engineering, and would like to take another undergraduate degree after I graduate from my current degree.

I can see from your angle, but the problem with modern education systems in all levels and almost all countries. Was they judge how much students had "learn via how many correct answer they are able to produce" under scar time. BUT NOT how much they really have actually learn and understood. I can pictured most of the stuff I've learn in class, but I'm having real difficult of putting down on paper in forms of formula (i.e. where the marks came from) and derives it to the state that it will give a so called "correct answer", from my experience I know this problems tends to eased out a bit as students advance into more technical papers (such that although things get harder, but is more specific and less board, such that in some sense it actually gets slightly easier, I don't know does it make sense to the people reading this thread).

This is why I'm posting this thread here, say when I talk to the lecturer over some topics I can effectively and efficiently relates to theories that was taught over class over the semester. But I'm having a hard time, when given a bunch of data and nothing more then a mere formula sheet and expected to come up with some sort of numerical solution. I'd be much happier if it was essay based examination, in relation to discussion of theories then making myself looks like a fool (and my mind half uncertain on what I've done). Hence the topic "picking the right equation for the question)

 

[Redbelly98]

Otherwise, when you start a question try to make sure the first thing you do is write down the information that the question tells you. Write the symbols and their values and, if possible, draw a diagram.

I always start by writing out all the quantities you are given in the question, even if it is obvious which equation to use, so that the examiner gets the feeling that you know what you are doing (even if you don't :P).

I'll echo that, and add: also write down what is being asked for, for example

v_final = ?​

With all the givens, plus the asked-for quantity, staring you in the face, that will hopefully be enough of a hint to pick the relevant equation.

Also, working out practice problems before the test is important.

The only reason why you use an equation should be because it saves you time. It should always be the case that, had you been given enogh time, you could have derived that equation you are using yourself from first principles.

Rather impractical statement in terms of passing exams, which have time limits. But I agree with the sentiment that one should have an understanding of what the equations mean.