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Official Thread For OCR Physics A G484 Jan 2011

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OCR know how to **** things up. I mean, first chemistry, and now this. It wasn't that bad of a paper, but what the **** is kilowatt hours doing in here? What is the definition for it? I just said it was 3.6x10^ something Joules. That SHM question with the tides was **** as well, read minutes instead of hours, so my calculations were all wrong. Realised my mistake at the very end and fixed it, but got the amplitude wrong etc etc.

G484 is a synoptic paper, so you should be able to recall ideas from G481 and G482. Just saying.

Reply 261

sulexk

Original post by 729

Pretty easy paper on the whole, here are some answers I remember.

Speed of the boxes was like 1.33

Mass of Helicopter was about 1500kg

It cost about £1.41 to use the fridge

The milk lost energy at about 19 J/s

The Speed of Nitrogen was 450m/s

for the milk question, did you use the number 114000 in your calculations, or something similar to this?

The mass of the helicopter, I think I got around 1626 ( speed was 12ms^-1, I think)

Reply 262

anttooking

Original post by vxa1314

and that it couldn't of been modeled as a SHM question since it doesn't oscillate either side.

Sour grapes

Reply 263

vxa1314

Original post by Kooper

My teacher said you get all marks if you write just the correct answer, and I hope that's right because my methods were practically illegible!

Doubt they can even read my handwriting. I want to say I'm dyslexic. Hope I get diagnosed to be dyslexic so I get my extra time.

A really clever guy in my class gets extra time. He already gets like 100%s and he STILL gets extra time. Holy ****.

Reply 264

vxa1314

Original post by sulexk

for the milk question, did you use the number 114000 in your calculations, or something similar to this?

The mass of the helicopter, I think I got around 1626 ( speed was 12ms^-1, I think)

I did <3

Reply 265

Kooper

Original post by vxa1314

90% of the people who used A = 2.5 maybe.

I used A = 5 and I still want to argue that the tides don't compress. So the equilibrium point should be where it was minimum. Therefore the gravitational pull of the moon should only pull the tides UP and it can't compress it. So the minimum amplitude should've been 13, and that it couldn't of been modeled as a SHM question since it doesn't oscillate either side.

But in SHM, the oscillator has to overshoot the equilibrium point. The question didn't care about how the force arose, it was just modelling the changing tide using acceleration of water level is proportional to -ve distance of water from equilibrium point. Also, for SHM you have to have equal amplitude on both sides of the eq. point. If you set A=5, it should be able to go down 5 as well as up.

I get where your coming from, but I think you're overthinking it!

Reply 266

729

Original post by sulexk

for the milk question, did you use the number 114000 in your calculations, or something similar to this?

The mass of the helicopter, I think I got around 1626 ( speed was 12ms^-1, I think)

Yh it was something like that

Reply 267

FruitsPunchSamurai

Original post by sulexk

for the milk question, did you use the number 114000 in your calculations, or something similar to this?

The mass of the helicopter, I think I got around 1626 ( speed was 12ms^-1, I think)

I remember using 114000 somewhere. I wrote - 19J/s though for my answer. :frown:

I hope I still get the marks.

Reply 268

tomdebs

i think the people that used A=2.5 were defo being too clever for their own good :tongue:

Reply 269

swond03

Seriously though after about 15 mins i was checking the front of the paper to make sure it was Newtonian, it was hardly what i've been studying since September

Reply 270

729

Original post by tomdebs

i think the people that used A=2.5 were defo being too clever for their own good :tongue:

But that's the right answer

Reply 271

Kooper

Original post by 729

But that's the right answer

Reply 272

sulexk

in terms of the fridge question at the end were they asking for the amount of energy transferred?

Reply 273

sulexk

What was the last part of the fridge question?

I remember a number 1628.57- from somewhere?

Reply 274

tomdebs

Original post by 729

But that's the right answer

so you really believe from that diagram that the equillibrium position was 15.5?
apart from being overcomplicated....it was 1 mark and i'm pretty sure it'll have been 2 if you're right...but everyone always thinks their right till the mark scheme gets out

Reply 275

sulexk

For the fridge question(Was this separate from the milk question), did they ask for the amount of energy transferred?

Reply 276

Kooper

It's impossible to see whether more people put 13 or 15.5 for the SHM question, so here's a poll:

http://www.thestudentroom.co.uk/showthread.php?t=1531173

Please vote for what you wrote!

Reply 277

Podge1

Original post by CharleyChester

Not gonna lie, saw the helicopter through the front of the exam paper and my first thought was: fml.

Hahahha I did the same but thought. Awesome, a p*** easy circular motion Q. How wrong I was. Defo got all marks on that one in end though. That rank altitude of satelite one on the other hand I have not. Even though I worked it out right after the exam :frown:

Reply 278

Podge1

Original post by OmegaPhoenix

Ahh! I think I just figured out the milk cooling graph!! It should have been a straight line negative gradient, then a flat line because it changes state, then another straight line with a steeper negative gradient!! Lost marks :frown:

Did anyone actually do that or am I crazy?

I did exactly that. Lets hope you are correct!!

Reply 279

jamesgil007

Hey!

Had some spare time at the end of the exam so scribbled down my answers to most Q's
(Not sure they are all right but most I think(Hope!))

1ai) Sum of the momentum before the collision equal to the sum after, if no external forces are applied
ii) Energy no conserved
iii) v=1.333 ms^-1
iv) KE before bigger than after ( Ke1= 13 Ke2= 3.something)
bi) 6123Kg
ii) 72000Kgms^-1
14400N
1500Kg

2i) Resultant force towards centre
ii) V changing directed towards centre
b) Radius= 2.9x10^7
ci) Thursters in direction of velocity (there are more answers)
ii) 4500ms^-1

3i) Unit where 1000 watts is transformed in an hour (Dunno how to word it?)
Cost=£1.41
Energy removed 114000
Rate= 19

Graph of milk- negative line from 18 then past 0 steeper negative line (Not sure if you have to include straight line along 0)

A=2.5m
T=2.22x10^-5
Vmax=3.5x10^-4 ms-1
x= 2.5cos(2(pi)2.2x10^-5t) (not sure if sin or cos?)

450 ms^-1

y=1/x, y=x

n= 8.4
mass= 0.023

Yeah sorry left out some of the wordy questions!