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Advanced Higher Physics 2011-2012 Discussion/Help Thread

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Original post by RyJ
Hi guys,

Just noticed this equation on scholar for polarisation:

I = I0cos2θ

Would I be right in saying we don't need to know about this?


MALUS' LAW you should know it and how to apply it - including units (for intensity), applications and experiments etc.
http://scienceworld.wolfram.com/physics/MalussLaw.html
(edited 11 years ago)
Original post by RyJ
Hey guys,

I know the chances of this derivation coming up are pretty remote, but does anyone know how to derive:

a = 2?


the a here relates to the radial acceleration which in the direction of positive unit r^ \hat{r} is negative, i.e. towards the center rotation.
a=dv/dt\vec{a} = d\vec{v}/dt always - its the definition of acceleration:
In this context simply state that δv=δθvt\delta v =-\delta \theta v_t so ar=ωvt=ω2ra_r =-\omega v_t = -\omega ^2 r

dont confuse a with α\alpha which is the angular acceleration, i.e. we can have a net value for a but 0 for α\alpha!
(edited 11 years ago)

Greetings fellow physicists.

On the formula sheet what does 'V' represent in the following equation:

V=(-Gm)/r

Also what is it measured in?

I have been doing past papers and the marking instructions always use:

Ep=(-GMm)/r

Can someone please explain?
Reply 103
Original post by theScottishBeast

Greetings fellow physicists.

On the formula sheet what does 'V' represent in the following equation:

V=(-Gm)/r

Also what is it measured in?

I have been doing past papers and the marking instructions always use:

Ep=(-GMm)/r

Can someone please explain?


In that equation, V is the gravitational potential (Jkg-1)

More often than not, the question will be asking you to calculate the gravitational potential energy, which uses the equation:

Ep=(-GMm)/r.

Hope this helps!
Thank you so much! It makes total sense now!
Reply 105
With less than a day to go, how are you all feeling? What do you think'll come up?
Reply 106
Jesus sorry folks forgot I even started this thread :colondollar:

Aiming for a C. As someone else's said I've just lost all motivation, got my unconditional, not doing ANYTHING to do with physics or even the sciences at uni or for my career(s)...
Enjoyed the course though, tons of interesting theoretical stuff that stimulates the curiosity within me delightfully :biggrin: Electronic circuitry/magnetic fields can go **** itself though...

How'd everyone's investigations go in the end?
Reply 107
Original post by RyJ
With less than a day to go, how are you all feeling? What do you think'll come up?


Hope to god(oh the irony) it'll be one of those one's where mechanics just pops up in a lot of the questions mysteriously. Derivations better not though...
Reply 108
Original post by Arianto
Hope to god(oh the irony) it'll be one of those one's where mechanics just pops up in a lot of the questions mysteriously. Derivations better not though...


Haha yeah, I'd be happy to derive one of the equations of motion - since they haven't come up in a bit. Ultimately, I'd like it to be consistent with the previous papers, because they all seem to be quite fair with the same types of questions. I'd like it to go something like this:

Q1-4: Mechanics; Relativistic motion, Rotational Dynamics (angular momentum etc), Gravitation, SHM.

After that, it normally goes Q5-8/9 Electronics and the rest on waves. I'd quite like a helical path question to come up as well, since I understand those quite well. I REALLY don't want a question about force between a number of charges, because I always seem to mess those up...

There may also be a wave-particle duality question/sub-question this year too!
Reply 109
Original post by RyJ
Haha yeah, I'd be happy to derive one of the equations of motion - since they haven't come up in a bit. Ultimately, I'd like it to be consistent with the previous papers, because they all seem to be quite fair with the same types of questions. I'd like it to go something like this:

Q1-4: Mechanics; Relativistic motion, Rotational Dynamics (angular momentum etc), Gravitation, SHM.

After that, it normally goes Q5-8/9 Electronics and the rest on waves. I'd quite like a helical path question to come up as well, since I understand those quite well. I REALLY don't want a question about force between a number of charges, because I always seem to mess those up...

There may also be a wave-particle duality question/sub-question this year too!


[hastily looks ups wave-particle duality in book]

In any case here's to everyone achieving what they're aiming for!

Btw, seeing as the exam is at 1pm, what's your tactical preperation gonna be like in the morning? What you gonna have for breakfast/lunch? At what time? When you gonna set off? What time will you wake from thy slumber? What soap will you use for a shower?!?! Assuming you're having one :colone:

Yeah I always fret about afternoon exam starts...
Reply 110
Original post by Arianto
[hastily looks ups wave-particle duality in book]

In any case here's to everyone achieving what they're aiming for!

Btw, seeing as the exam is at 1pm, what's your tactical preperation gonna be like in the morning? What you gonna have for breakfast/lunch? At what time? When you gonna set off? What time will you wake from thy slumber? What soap will you use for a shower?!?! Assuming you're having one :colone:

Yeah I always fret about afternoon exam starts...


I'll probably head into school at 9 for some last minute reassurance/tears. I doubt I'll have lunch if I'm honest (Exam starts before our school's canteen opens for lunch) :confused:

I have my pens and calculator neatly placed on my table, pens spaced separately (I'm a bit obsessive compulsive, in case you couldn't tell).

Without a doubt, adrenaline will start to kick in within the next few hours and I won't be able to sleep!

I prefer exams in the afternoon, means I'll be fully awake and won't end up trying to fill out the front of the exam booklet with a non-switched-on pen... :colondollar:
Reply 111
Good luck everyone! :biggrin:
Reply 112
Just started revision on unite 3 now...
So how did you guys find it? I found the paper quite unusual, not the same format/type of questions as previous years... I will try and type up my answers when i get home.


This was posted from The Student Room's iPhone/iPad App
I guess I found it meh? I mean it was expecting it to be really hard and I don't think it was as hard as I'd expect it to be. Think it will be some sort of miracle if I get an A though. Ah well off to university regardless!
(edited 11 years ago)
Reply 115
I'm really scared I'm not getting an A after that... :frown: I messed up so many questions and I guessed the answers to some! How many marks do you think I could lose to still get an A?
Reply 116
Original post by Marcus4004
So how did you guys find it? I found the paper quite unusual, not the same format/type of questions as previous years... I will try and type up my answers when i get home.


This was posted from The Student Room's iPhone/iPad App


Thought it was on the whole OK. Unit 1 questions were trickier than usual, but unit three was piss easy. Kind of a nice change in my book! :L
Reply 117
Original post by Marcus4004
So how did you guys find it? I found the paper quite unusual, not the same format/type of questions as previous years... I will try and type up my answers when i get home.


Agreed, the questions did seem a bit different. Almost missed out a 3 mark question by accident, caught it in my last 10 minutes of checking over answers!
Original post by brian19
I'm really scared I'm not getting an A after that... :frown: I messed up so many questions and I guessed the answers to some! How many marks do you think I could lose to still get an A?


Depends how you did on your investigation. If you got 50% on your investigation you need around 75% in the exam to get an A.

60% on your investigation -> 72.5% on the exam
70% on your investigation -> 70% on the exam
75% on your investigation -> 68.75% on the exam
80% on your investigation -> 67.5% on the exam
90% on your investigation -> 65% on the exam
100% on your investigation -> 62.5% on the exam
Reply 119
I found it pretty good, answered every question and didn't have to guess any so hopefully an A.

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