Official Thread For OCR Physics A G484 Jan 2011

I can't understand myself why the v^2=GM/r was worth 4 marks. My only guess is that they wanted us to derive the equation first, (as it's not on the data sheet). So I did.

What did you get for your amplitude in the tide question? and the last moles question too?

Yeah looking back on it I think they did want you to derive it... but I didn't think to do it :frown:

Amplitude is 2.5m, because it is oscillating about the mid point of the two tides, which is 15.5m
Last moles question... I think I got 0.02 kg lost.... I was kicking myself as I had done an identical question last night and forgot the method to do it!

Reply 321

nirvana001

this was way harder than jan 10 an very much harder than june 10... do u think 44/60 wud scrape an A??

Reply 322

Masderchef

1

Original post by Ben Adams

Yeah looking back on it I think they did want you to derive it... but I didn't think to do it :frown:

Amplitude is 2.5m, because it is oscillating about the mid point of the two tides, which is 15.5m
Last moles question... I think I got 0.02 kg lost.... I was kicking myself as I had done an identical question last night and forgot the method to do it!

I got 5 for the amplitude(18-13). I think it might be wrong though.

I might have got 0.0260Kg for the last part. How did you get to your answer for this?

Reply 323

rob...

I think the amplitude is 2.5m min was 13 and max was 18 so equilibrium was 15.5 and amp is distance from the equilibrium position...
Apropos finding the radius, I used keepers third and T=2pi/v to get the right answer. As the question didn't say from first principles, do you reckon I'd get the marks? XD

Reply 324

cheribum801

Original post by rob...

I thought the helicopter question took time to think about. It wasn't exactly a normal mechanics question.

"Newtonian World"? More like "Physics: All Aspects of".

What a fantastic way of putting it :biggrin:

That helicopter question took me ages to work out what I was doing... I left it and came back to it at the end with my answer squished in at the bottom of the page underneath a pile of nonsensical equations and working out :s-smilie:

I got something like 6126.something, I feel like I can literally recite off my answers to every question at the moment...

Reply 325

gdsffdes

was three significant figures ok for the majority of the answers?

Reply 326

sc0307

8

Original post by gdsffdes

was three significant figures ok for the majority of the answers?

I gave my answers to the number of sig figs they used for the values they gave in the question.

Reply 327

yu80359

51/60 around for this paper enough to get an A?

Reply 328

anshul95

11

Original post by yu80359

51/60 around for this paper enough to get an A?

more than enough. Grade boundaries will probably be very low maybe around 43/42 for an A. I was lucky in that I like papers with more calculations.

Reply 329

Kooper

Has anyone got a copy of the paper they could upload?

Reply 330

FruitsPunchSamurai

A copy of the paper would be really nice :smile:

Does anyone remember whether they had to add the radius of the earth for the four mark satellite calculation question? Someone in school mentioned that they did. Getting sort of scared, since I don't remember doing that :frown:

Edit: Then again, that's not possible. I don't think we were given the radius of the earth in the question anyway.

(edited 13 years ago)

Reply 331

jammydav93

Original post by FruitsPunchSamurai

A copy of the paper would be really nice :smile:

Does anyone remember whether they had to add the radius of the earth for the four mark satellite calculation question? Someone in school mentioned that they did. Getting sort of scared, since I don't remember doing that :frown:

Edit: Then again, that's not possible. I don't think we were given the radius of the earth in the question anyway.

No we didn't as we weren't given the radius - the distance was from the centre of the earth so there is no need for the radius, did you get something like 2.7-2.9x10^7 m?

Reply 332

jammydav93

Original post by Kooper

Has anyone got a copy of the paper they could upload?

I'll try and get one on Monday and upload it here,

Reply 333

FruitsPunchSamurai

Original post by jammydav93

No we didn't as we weren't given the radius - the distance was from the centre of the earth so there is no need for the radius, did you get something like 2.7-2.9x10^7 m?

I can't remember the exact value, but I remember my working.

GM/r = v^2
After that it's just number crunching.

Reply 334

Michael_4180

Original post by FruitsPunchSamurai

I can't remember the exact value, but I remember my working.

GM/r = v^2
After that it's just number crunching.

it was 2.92 x10^7

Reply 335

sc0307

8

Original post by Michael_4180

it was 2.92 x10^7

how many marks do you think ill get for deriving v^2=GM/r

Reply 336

Michael_4180

Original post by sc0307

how many marks do you think ill get for deriving v^2=GM/r

Probably 1 mark for deriving it, 1 mark for re-arranging it to make r the subject, 1 for substituting the values, and the final mark for an accurate answer.