Physics Discussions

PrecariousNuts

I thought that was a really easy question...

subway_ie

Originally posted by PrecariousNuts
I thought that was a really easy question...

f = GMm/d^2 = mv^2/r, right?

PrecariousNuts

thats it in its entirety

subway_ie

Originally posted by PrecariousNuts
thats it in its entirety

So that makes me all the more curious as to how I got such a stupid answer. Easy question, nice, rounded numbers. Yet I get 6.7164E25. I'd understand it maybe if it was some kind of insanely complex thing where you had multiple equations to remember and fill in, but they're probbaly the easiest equations to remember/use in all of circular motion. It just doesn't add up.

Such a terrible, terrible pun.

DS

but apperantly there was TOO much maths on it

Well that's understandable. The reason I found it so nice was for that reason. And I'd say the rest of the people here happy with it are also higher maths students. They gave a huge amount of marks for calculations, looking over it now. Suited me down to the ground, but I can understand how pass maths people would find some of those big calculations intimidating. They were in fact very straightforward, it was just a case of applying the formulae with the info you were given.

subway_ie

Originally posted by Discharger Snake
Well that's understandable. The reason I found it so nice was for that reason. And I'd say the rest of the people here happy with it are also higher maths students. They gave a huge amount of marks for calculations, looking over it now.

I thought there was a nice balance between calculations and definitions, more so than previous years. A huge part of physics is actually doing calculations and manipulating formulas, so it's only right that about 40% of the exam should be calculations. The total marks on the paper is 608 (the total amount going for ALL questions on the paper - obviously you can only be counted on 3+5) and the total amount of marks going for calculations is 253. That means the paper is roughly 42% calculations. Obviously you can't be counted on all the questions on the paper, but it gives a rough guide for the marks distribution.

subway_ie

My god. This is like one massive super-physics thread. It's got all the power/information of at least 3 threads combined. Seamus gettin' bored then?

PrecariousNuts

Yeah i just noticed that it fused, how did he manage to overcome the electrostatic forces?? He must have had this thread at temperatures exceeding 10^8 K for a while

Envy

Seamus gettin' bored then?

He's not the only one.

subway_ie

Yeah i just noticed that it fused, how did he manage to overcome the electrostatic forces?? He must have had this thread at temperatures exceeding 10^8 K for a while

Well, at least we now know that the powers of moderators exceed those of the puny forces of nature. Electrostaic forces, pffff. Think of all the mass-energy which must have been converted when the threads were fused. It's awesome.

PrecariousNuts

hehe

Time Magazine

I was happy with the paper. I passed no probs. Thought maybe a good C but depends. I made a few howlers. Thermionic emission is not giving off heat (*smacks forehead*) and the like. Did all 4 experiments. Thought I did 6 Section B's but I can't count - only did 5. But ah well. Not too bad. I might use it for points. But Physics is one of my lower ones (along with Maths and Irish). But I will have to use 2 of them. Fingers crossed I get that A1 in Economics now...

The Shol'va

Wooooooo!!!! Answered all the questions, even 10 (b), even though I never looked at that option :P

subway_ie

Originally posted by The Shol'va
Wooooooo!!!! Answered all the questions, even 10 (b), even though I never looked at that option :P

Most people can do that if they have a decent physics teacher - the applied electricity option has only slightly more material than the normal electricity section. I was thinking about doing it, because I wasn't sure about the particle physics decays, but I ran out of time. But how did you manage to answer all the questions in three hours? I was writing the whole time and I only got 3 from section A and 6 from section B done (Only 4 of the section B were done well though. I seem to have developed a habit of making up my own genius, but wrong, formulas).

DS

It's pretty doable to get all the questions done. I got all Section A done and 6 from B. Had time for an 11th question but instead I read back through everything and made sure I didn't skip any questions by mistake, which I always manage to do because there's no numbers beside the questions, it's all text.

subway_ie

It myst be just me then. I did 3 from section A and 6 from B, spent the rest of the time going back over bits I didn't/couldn't do at the time and correcting my (many, many) stupid mistakes. I suppose I could have done an extra one from B, but then the quality of my others would have been reduced with all the stupid mistakes/omissions.

That thing where they number some parts of the question and not others is pretty damn annoying. Can get confusing - I just bring in green and yellow highlighters to highlight what I've done/need to do... so by the time I come out of the exam you can't actually see any pink on the page, all just highlighter.

Bullockshaver

Im such a fool for Question 6 the one on conservation of momentum i took the masses in terms of g so i thought it was a mass of 98kg for the first mass i get confused with the applied maths in it most of time given masses in terms of g. The Physics paper was really easy otherwise. Do correctors tend to give out full marks quite easily?

subway_ie

Dunno why you would tink that they'd give you masses in terms of though... not a huge mistake. Probably a confusing one for the examiner.

Generally you won't get top marks unless it's word perfect. You can't really go by the marking schemes of past years either, since they only give keywords.

DS

Weight is given in terms of g, never mass.

subway_ie

Originally posted by Discharger Snake
Weight is given in terms of g, never mass.

I wonder if they did that intentionally just to try to "trick people out" by making it look like acceleration due to gravity instead of writing 0.008Kg? I'm sure more people than just Bullockshaver made the same mistake.

DS

I doubt it. The only people familiar with weight in terms of g are applied maths students, who'd usually be pretty tuned in. They never do that in physics anyway, or at least I've never seen it. In physics everything is a number, my teacher hated when I'd leave my answer in terms of pi, and she'd get really annoyed when I'd tell her how much more accurate it is.

subway_ie

Yeah, I suppose you don't really use g like that very much in physics. Our teacher used to be the same about numbers, but what would drive him even more crazy was when I always wrote m/s or m/s^s instead of m.s^2. He used to freak whenever he saw that. Happy days.

Seifer

Beautiful paper. Hopefully have my A1. Here's a run-down:

Q1: This was pretty funny; on the t values it has t/ms and I thought it was metres per second and was writing out a little error on exam paper note to the examiner before I coped it was milliseconds! Worked out perfectly, got g to be 9.9115 ms^-2.

Q3: Perfect

Q4: Lovely. 1.142 x 10^-6 ohm metres

Q5: Easy. (a) 13 N (b) 980 Pa (d) 3 dB (e) 20 m^-1 (h) 9 years (j) udd

Q6: Applied maths in its very simplest form. (i) 1.98 ms^-1 (ii) 2.475 ms^-1 0.0123 N

Q7: Nice but I screwed up the calculations. Had method so I'll only lose a few. (i) 212250J (ii) 80J (iii) 2653.125 s

Q9: Cool. (i) 1.042 x 10^15 Hz (ii) 2.846753 x 10^(- can't seen if its a minus or not) 14 J

Q10: Fine. 1.248404397 x 10^-13 J ( I like long decimals)

Q12: Great. Did 3 parts. 2.015 x 10^30 kg

Cathy

Originally posted by Seifer Q1: This was pretty funny; on the t values it has t/ms and I thought it was metres per second and was writing out a little error on exam paper note to the examiner before I coped it was milliseconds!

Damn it, I thought it was an error too! I just took it to be seconds... I thought they were really big values... oh well. Done now.