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OCR B: Advancing Physics - G494 (Rise and Fall...) 24/1/2012

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Original post by rachmcg666
http://www.ocr.org.uk/download/kd/ocr_9654_kd_gce_spec.pdf

- just found in the spec (page 38) that g = -Gm/r^2 is the radial component & Vgrav = -GM/r
What's the difference between Vgrav & radial component g?
arrrrgh!

g is the acceleration due to gravity, or the force per kilogram. Vgrav is the potential - the amount of energy per kilogram of matter. So basically, one's force per kilogram, and the other's energy per kilogram. Hence why, by multiplying by the mass of the object, you'll get the force and energy respectively. :smile:

Might want to quote me next time so I see it :tongue:
Original post by Contrad!ction.
quote me


you my friend, are a life saver. Thank you! i understand now!
P.s What school in dorset do you go to? :smile:
Original post by rachmcg666
you my friend, are a life saver. Thank you! i understand now!
P.s What school in dorset do you go to? :smile:

Haha, no probs :biggrin:

Poole High - yours? :smile:
Original post by Contrad!ction.
Haha, no probs :biggrin:

Poole High - yours? :smile:


i've been struggling on that one since September - you have no idea how grateful I am!
& Parkstone grammar {: small world ay!
Original post by rachmcg666
i've been struggling on that one since September - you have no idea how grateful I am!
& Parkstone grammar {: small world ay!


Ah! Did you do the maths challenge? Our further maths class came to your school for the lectures and then did the UKMT thing in your maths building.

How's the kinetic theory going?
Original post by Contrad!ction.
Ah! Did you do the maths challenge? Our further maths class came to your school for the lectures and then did the UKMT thing in your maths building.

How's the kinetic theory going?



Ahh, nope i remember skipping that day! :biggrin:
I love maths but i didn't want to waste a day of no learning, as the previous year the lectures were on maths in the Simpsons - interesting but of no use. And i hate the maths challenge with a passion!

& Kinetic theory is all good! I find the 2 chapters at the end (13&14) on matter easy, it's the gravitation i've been getting confused over - which is chapter 11 in the text book i think? Oh & SHM - we only finished learning it a week or two ago so it's still a little new to me - especially since the equations in the formula book are expressed oddly!

Are there any parts of the module you find difficult or are you fine with it all? It seems like you know your stuff! (:

Also; do you find the textbook extremely unhelpful? - i remember it having a little poem in on one page instead of useful information. Seriously, what the hell?
Original post by rachmcg666
Ahh, nope i remember skipping that day! :biggrin:
I love maths but i didn't want to waste a day of no learning, as the previous year the lectures were on maths in the Simpsons - interesting but of no use. And i hate the maths challenge with a passion!

& Kinetic theory is all good! I find the 2 chapters at the end (13&14) on matter easy, it's the gravitation i've been getting confused over - which is chapter 11 in the text book i think? Oh & SHM - we only finished learning it a week or two ago so it's still a little new to me - especially since the equations in the formula book are expressed oddly!

Are there any parts of the module you find difficult or are you fine with it all? It seems like you know your stuff! (:

Also; do you find the textbook extremely unhelpful? - i remember it having a little poem in on one page instead of useful information. Seriously, what the hell?


Haha, they did mention the Simpsons :tongue: I hate the maths challenge, because I'm generally not very good at it, and I hate being bad at something. :tongue:

No idea what chapter it is - we don't get a textbook. Our physics teachers are effectively our textbooks. :tongue: SHM can be a tad annoying, I know the explanations of why an equation shows an object undergoes SHM tend to lose me marks because I forget to use the word 'constant' :angry:

Generally, explanations. I'm fine on the maths, and if I don't know how to answer a question, I tend to bodge it. But knowing what they want to write can sometimes be hard.

No textbook - I do however have the lovely CGP revision guide. "Our Physics teacher was a Great Attractor: everyone fell for him" and "momentum will never be an endangered species - it's always conserved" are just two of its contributions towards my physics grade. :tongue:

And from G495: "Electric fields: one way to roast beef".

"Stop meson around and do some work".

"Lumberjacks are great musicians - they have a natural logarithm".
Original post by Contrad!ction.
"Lumberjacks are great musicians - they have a natural logarithm".


haha, they;re brilliant :') & the main textbook is horrendous anyway so you're not missing out on anything (:
& i'm okay at the explanations when i know what they're talking about. But i hate the questions that say 'show that...' when I CAN'T SHOW IT.
arrrrrrrgghhh.
Reply 28
:eek: Have this exam and so scared! I did 2 papers and I managed to get A's, but I need a high A :sad: Because I only scraped the A at AS and I have a feeling I'm going to scrape a B in the coursework again :eek:
Reply 29
I have this exam too and i'm petrified :frown: got an E in the mock we just did, 22/60 :frown:
Reply 30

also, the June 2011 Mark Scheme would be nice :')
Original post by rachmcg666
haha, they;re brilliant :') & the main textbook is horrendous anyway so you're not missing out on anything (:
& i'm okay at the explanations when i know what they're talking about. But i hate the questions that say 'show that...' when I CAN'T SHOW IT.
arrrrrrrgghhh.


The formula's generally in the book, but it might need rearranging. Are you okay on rearranging equations/substituting equations?
Original post by beakybal4
I have this exam too and i'm petrified :frown: got an E in the mock we just did, 22/60 :frown:


Try to keep calm - I got a U in my G491 mock, but got a decent A in the real thing. Just work out where your main weaknesses are and try to address them. If you need a hand or anything explaining, I can give it a go :smile:
Reply 33
How on earth do you guys manage to remember all the units for everything :frown: So annoying!
Original post by Contrad!ction.
Try to keep calm - I got a U in my G491 mock, but got a decent A in the real thing. Just work out where your main weaknesses are and try to address them. If you need a hand or anything explaining, I can give it a go :smile:


Hello again contradiction! Don't know if you remember me but we converesed quite abit just before and after the last physics exam :tongue:.

Just about to start my cramming now :jitsu:
Reply 35
Original post by Contrad!ction.


Would appreciate some help on this question - thanks for your help!
(edited 12 years ago)
Original post by In One Ear
Hello again contradiction! Don't know if you remember me but we converesed quite abit just before and after the last physics exam :tongue:.

Just about to start my cramming now :jitsu:


I have 3 exams in 3 days next week, no idea how I'm going to fit it all in. Done a bit of revision earlier, but then I had to prioritise 4 maths exams. :s-smilie:

Original post by Ivo
Would appreciate some help on this question - thanks for your help!

Well, equipotential lines join points of equal potential. Equipotential lines are always perpendicular to field lines - does this help?
Original post by Revent
How on earth do you guys manage to remember all the units for everything :frown: So annoying!


As in J s-1, N etc? If I forget, I look at the units and try to work it out - like gravitational potential energy is gravitational potential multiplied by mass, so the units of gravitational potential will be energy ÷ mass = J kg-1...
Reply 38
Original post by Contrad!ction.
As in J s-1, N etc? If I forget, I look at the units and try to work it out - like gravitational potential energy is gravitational potential multiplied by mass, so the units of gravitational potential will be energy ÷ mass = J kg-1...


Yeah! That kinda stuff, I try to do that, but it rarely works for me :frown:
Original post by Revent
Yeah! That kinda stuff, I try to do that, but it rarely works for me :frown:


In that case, try memorising. Flash cards with the quantity on one side, and the units on another. Perhaps some cards with units on one side, and alternative units on the other. They can help you memorise things pretty quickly. And practice - try doing past papers, but cover the units they give you and try to write them yourself.

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