in other words, you're only good at the classes they pass you for simply showing up and dressing out?

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Do you have stairs in your house?

With mathematics it is really all down to the teacher, probably moreso than English or Art or other 'creative' subjects. The key to mathematics is simply to understand it. A lot of people tend to just try to memorise a certain process or certain keywords and then remember what to do from there, but really if you just understand it, there's nothing you need to remember. This is what irritated me about History and to a lesser extent Sociology. In both of those, you had to write a short essay on something or rather, and refer to names and dates. Dates wasn't that hard, as I'm fairly good at remembering numbers, but remembering names annoyed me. I tended to just understand the concept or perspective and learn how to apply it. It is totally irrelevant to me who said it, but rather it is what was that that is important. (it's the same on this forum, actually. I never bother reading the 'name' column).

There isn't always that clear-cut divide between the 'numerical' type subjects (Mathematics, Chemistry, Physics) and the 'creative' type subjects (English, Art, History). I don't know about your exams, but the hardest part of any Mathematics question here is to work out what exactly the question is asking you to do. Do you have to integrate an equation to find the area under it, do you have to factorise the polynomial, do you have to find the discriminant? You have to really analyse the question, understand the question, and understand the mathematical concepts. You can't do that just by memorising things. The question might be really very abstract and you have to think creatively, and use several concepts together. That thinking is not dissimilar to when analysing a Shakespeare text or when writing for a particular purpose to a particular audience.
Similarly, when studying English grammar you have to have a very structural approach, looking at a word and deciding whether it is a noun, verb, adjective, adverb, noun phrase, preposition, determiner, based on a set of rules about each type of word.
Just focussing on one type of thinking isn't helpful, and you should exercise your brain in the area that you are weakest. Having a decent all-round education is very beneficial.

This is why I chose at AS-level to study Maths, Physics, English and Sociology. I'm certainly a lot stronger in the first two, but I'm still quite competent in the last two too.

I don't have a worst subject.

Best: English, sad as it is.

Worst: ALL math, but ESPECIALLY physics. I took AP physics and I couldn't even tell you how long it would take a penny to fall 10 feet. It makes no sense. Second worst is science. Not really all science, mainly Bio and Chem. I actually like earth science / geography / geology.

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Have a good one,
Freelancer

Exactly. Why do endless math to find out about the penny when it would be easier to do it in real life and get a result that you know is accurate?



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Old aunts used to come up to me at weddings, poking me in the ribs and cackling, telling me, "You're next." They stopped after I started doing the same thing to them at funerals.

How exactly do you 'know' that is accurate?
Using a precise mathematical model to calculate the result is far more accurate than simply carrying out the experiment where there will be a whole heap of random and systematic errors that will affect the result.
I certainly hope you're not suggesting that mathematics is 'useless' or any such argument, as without mathematics you wouldn't have your computer, you wouldn't have this forum, you wouldn't have the chair you're sitting on or the house you're living in (unless you're sitting on a box and living in a cave).

Some people just don't realize that the problems you do in books and in school are there simply to TEACH you the application. They're not real world problems - they don't have scientists that sit around all day in lab coats performing experiments and calculations to find out how far a penny will shoot... they already know that. That's why they're using it to teach you the basics to Physics.

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Do you have stairs in your house?

Mort-Hog, you think doing math to figure it out is more accurate than, just, dropping the penny and timing it? Heh.. Okay...

P.S. Maybe if you're the one doing the math, not me.

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Have a good one,
Freelancer

You have a penny and you want to work out...how long it takes to reach the floor if I drop it from a height of 5 metres.

s = 5 m
u = 0
a = 9.81 ms^-2

s = ut + 1/2 at^2
s = 1/2 at^2
(2s / a)^(1/2) = t

(10 / 9.81)^(1/2) = t
t = 1.01s

So, it will take 1.01 seconds for a penny to fall 5 metres from rest (at 5 metres air resistance is negligeble).
I didn't have to get out my chair, I didn't have to find a penny, I didn't have to find a stopwatch. There was no error in me pressing the button at the wrong time, there was no error in the electronics of the stopwatch, there was no error in me accidentally throwing the penny rather than dropping it.

[This message has been edited by Mort-Hog (edited June 04, 2004).]

Yeah, most of the purpose behind the calculations are to avoid human error anyway...
besides, what if you were doing something that counted on the penny falling for a certain ammount of time? Wouldn't it be better to calculate how high to place it instead of trial and error?

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Do you have stairs in your house?

[This message has been edited by Correction (edited June 04, 2004).]

Okay, so you're saying, you want to find out...say...
How far a penny will fall from rest in 4 seconds?

t = 10 s
u = 0
a = 9.81 ms^-2

s = ut + 1/2at^2
s = 1/2 * 9.81 * 16
s = 78.5 m

If a penny fell for 4 seconds it would travel 78.5 metres.

I look at that equationm, and I have very little idea what any of it means.



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Old aunts used to come up to me at weddings, poking me in the ribs and cackling, telling me, "You're next." They stopped after I started doing the same thing to them at funerals.

the SUVAT equations are very elementary

s = displacement (distance)
u = initial velocity
v = final velocity
a = acceleration
t = time

Then there are 5 easy to learn equations (which can all be derived from first principles). Basically, the idea is that you can work out anything about the system knowing only 3 of those values (I think).

Calculus allows you to take into account things like air-resistance, simple harmonic motion, damped harmonic motion etc.

The whole point of doing this rather than just doing it by experimentation is that you'll always get a far more accurate result. The best accuracy you could get from using a stopwatch and dropping a coin 5m is that it would take "about a second".

As for best subjects, either maths or anything purely conceptual (rather than factual). I got good grads on all my A-Levels with just a few hours revision because I understood things and it didn't matter what particular name things had been given.

I just had an exam where I did worse than I should have because although I understand just about everything, a significant portion of the marks were for things like "explain what the L2CAP does"

Best: Physics (A+) Worst: French (B)



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No signature for you.

What subject was that?

English is my best and worst subject. My teachers were all like "Wee! He can write!", which quickly morphed to "Why doesn't he write for me anymore? I am suck at teaching!" which was finally replaced with "Ah! He writes only occasionally, when several unrelated deadlines reach some critical conjunction and the moon is full. I will give him a D. I am at peace."

Yep.

[This message has been edited by Ictus (edited June 04, 2004).]

Except your assuming that the Gravitational constant of 9.81 m/s^2 is constant everywhere. It's actually an average. The actual acceleration due to gravity varies depending on altitude your at (from sea level).

We actually used a far more accurate means to calculate the acceleration due to gravity in my General Physics class in college. It involved using a computer, electrical sensing plates, a release mechanism, and a metal ball. For our location, the acceleration due to gravity was ~9.792

And no, at 5 meters air resistance isn't neglagible. If it was, then at the 1 metere we were at, we would of got the same result every time we did the experiment. The above value is the average of the closest 3 out of 5 (the other 2 were too far off to include).

You see, what your calling "Errors" I call "unforseen varibles". Thus why you should always experiment in the real world.

But again, as mentioned above, these are just simple exercises. Just remember that you should always test your stuff in the rear world.

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Try not, do; or do not.

Best: History

Worst: Math or Science.

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"This thread is still alive? Someone should kill it."

Yes but there are many cases when it would be impossible to try such things out in the real world (the penny dropping is a simple exercise and therefore you would be able to test it in real life) However its the build up to more complicated stuff which you would have to use mathematical models for because you cannot experiment with it real life.



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/fluffle

Friend14, I think Mort-Hog is perfectly aware that the SUVAT equations don't give perfect answers, it wasn't really necessary for you to state the obvious. The point is that the SUVAT equations give you far more accurate answers than someone with a stopwatch can get. The inacccuracies are at least consistant if you do it mathematically, whereas human error results in a different answer every time you do it.

If the time it takes a penny to drop 5 metres was of some critical importance, you'd use a better set of equations with more accurate values for gravity and air resistance.

Best: Math (and English, at one point)
Worst: Everything else (especially history).

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Genesis 22:2-5 - And God said unto Abraham "You must kill your son, Isaac." And Abraham said "What? I can't hear you! You'll have to speak into the microphone." And God said "Check, check, check, check. Jerry, can you pull the high end out. I'm getting some hiss up here."
Valuable Life Lesson: Frog + Potato Gun = Blindness
Catalog of Electronic Components - Complete IC data sheets
National Electrical Code® (NEC®) Online - Legal requirements for wiring projects.

[This message has been edited by DogSRoOL (edited June 06, 2004).]

I've actually never seen u and v used to represent those things. It was always V with subscripts, both in high school and college. That was something that was always confusing while taking electronics & physics at the same time. Dear Lord! How many things can V represent!?

Part of my point was that, while it was obvious to you, it's not always obvious to everyone else. Which is part of the issues that people have already mentioned that they have with Math and the like.

BTW, it's not always human error, the majority of the time it's actually erroneous real world varibles. There are still things all around us that we have an "idea" of but don't understand completely, of course we get a little closer each day.




Actually, I was pointing out the fundamental difference between Physicist and Engineers. Physicist use words such as "neglagible" all the time. Basically their way of saying, it only represents a small change to our answer and it's simply not worth the time to spend on the increased amount of math involved. Where an engineer, on the other hand, realizes that that "neglagible" amount could be the difference between life and death.

Thus my point was simply that when considering (note I said considering and not solving) any problem, rather rudamentry or advanced, you should always keep in mind all concievable varibles....rather their "neglagible" or not. This is why many people struggle through the math part of physics (or math in general). They have a need to understand all the logic behind every aspect of it. If they don't get even one small peice of it, they trap themselves in a mental loop until they either figure it out for themselves or someone else comes along and helps them out of it (or they simply give up). Thus leading us back to the previous posts before Mort-Hog joined in.

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Try not, do; or do not.

[This message has been edited by Friend14 (edited June 06, 2004).]

Last semester my best subject was Astronomy, and my worst subject was AP Physics.

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"The only thing necessary for the triumph of evil is for good men to do nothing." - Edmund Burke

"Never let your sense of morals prevent you from doing what is right." -Isaac Asimov

If air resistance is significant then you'll have to use a different model, namely resolving forces using a Newtonian model.
For this, you'd have to use measure the mass of the penny and then calculate the horizontal and vertical components of the forces. The horizontal forces should be 0, if you're dropping the penny vertically.
The most common use of this is to calculate the air resistance. That is, you work it out assuming there is no air resistance, and then you experiment in order to calculate the difference, and thus find the air resistance. That isn't an especially mathmatical way, as the air resistance could probably be calculated from the density and temperature of air. As you pointed out, though, physicists work on the theory, and engineers work on applying it. If you were to be designing a structure to be travelling at close to the speed of light then using a Newtonian model would not be suitable, and you would have to use the Einsteinian model of relativity. If you were designing very small structures, like a nano-engineer, neither of those models would be suitable and you would have to use quantum mechanics. But it is the physicist that develops those mathematical models.