OCR Physics A - G485: Fields, Particles & Frontiers of Physics - June 2012

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Reply 1180

Jetblast

Original post by mack94

Feel like hanging myself after that exam lool

I'm about to, wanna join? :colone:

Reply 1181

Madrid Apple

Original post by 4 Mathlete the win

I got it as 0.21cm

When you plug it back in e^(-0.033*21) it gives 0.5, so I'm fairly sure 21 was the right answer.

Reply 1182

jahani08

Original post by Picture~Perfect

If no-one has beaten me to it, I was going to copy the paper and provide a link.

please do! i'm going crazy here, i think i've done terribly

Reply 1183

Joseppea

Original post by jamie3009

what did people get for working the activity out using your answer to b.i on about question 2 or 3? My mind whent blank and i couldnt do it. Must have been easy as it was only 1 mark

That took me ages to work out until I realised: P = E/t and 1/t = A, so P = EA etc.
:smile:

Reply 1184

SamXi

Original post by Madrid Apple

When you plug it back in e^(-0.033*21) it gives 0.5, so I'm fairly sure 21 was the right answer.

You were meant to leave it in CM's not convert it

Edit: unless you specified M^-1

(edited 11 years ago)

Reply 1185

jahani08

Original post by Jetblast

I'm about to, wanna join? :colone:

maybe we should all meet and do it together :P

Reply 1186

ReTurd

Original post by Madrid Apple

Wasn't it 3.33 cm though, so ln(2)/0.033=21

It asked for it in cm didnt it?
I put 2100cm

Reply 1187

jamesvernon

Original post by Madrid Apple

When you plug it back in e^(-0.033*21) it gives 0.5, so I'm fairly sure 21 was the right answer.

But the value was given to you in cm. 3.33cm

Hence if you do e^-(3.33*0.21) you also get 0.5

I found the paper nice :smile:

Reply 1188

Fing4

Original post by Madrid Apple

Wasn't it 3.33 cm though, so ln(2)/0.033=21

to convert it from centimetres to metres you do 3.33*(10^-2)^-1 because mew is measured in cm^-1

(edited 11 years ago)

Reply 1189

jahani08

for the nuclear fission question, how did people work out the energy produced by the reactor core?

Reply 1190

-Zephyr-

I think it went alright overall... there just seemed to be a few strange questions. :/

Two properties of X-rays anyone? I put 1. short wavelength 2. can cause ionisation

Definitely messed up the one about the alpha particle and the gold nucleus... the graph and the 2 mark for explaning why the gold nucleus is moving when the alpha stops. :frown:

Reply 1191

Madrid Apple

Original post by jamesvernon

But the value was given to you in cm. 3.33cm

Hence if you do e^-(3.33*0.21) you also get 0.5

I found the paper nice :smile:

Yeah but you have to convert it to m before doing the equation.

And yeah the answer may have been in cm, can't remember, then 2100 cm

Reply 1192

bunnyhana

kind of hate my life now..... reading posts is depressing...

Reply 1193

jamesvernon

Original post by jahani08

for the nuclear fission question, how did people work out the energy produced by the reactor core?

You knew the total output, and the % converted to electrical.

So the Amount of electrical / 0.22 = The output of the core.

Sorry i don't remember numbers

Reply 1194

mfmdanny

Original post by Jetblast

I'm about to, wanna join? :colone:

Before you do that, may I say one thing:
:bl:

Reply 1195

jamesvernon

Original post by Madrid Apple

Yeah but you have to convert it to m before doing the equation.

And yeah the answer may have been in cm, can't remember, then 2100 cm

You don't *HAVE* to convert it to metres. Just as long as you change your units to keep it correct. and since it wanted it in cm's anyway, you didnt have to convert.

Reply 1196

SS*

Original post by mfmdanny

At the time, I thought quite well, I missed a few questions. But when I look back I'm not sure, I want to look at the paper.

You?

Same...I thought it wasn't too bad, but after reading all these posts...maybe not.

I am hoping the grade boundaries are lower than they were in January!

Reply 1197

Madrid Apple

Original post by jamesvernon

You don't *HAVE* to convert it to metres. Just as long as you change your units to keep it correct. and since it wanted it in cm's anyway, you didnt have to convert.

Normally you'd be right, but as it's an exponential the rules are different, and in the book you'll see that the attenuation coefficient for Bone is 53 m^-1

Reply 1198

delllboy

Original post by Madrid Apple

When you plug it back in e^(-0.033*21) it gives 0.5, so I'm fairly sure 21 was the right answer.

im sure you couldve done either to work out the right answer. if you used metres for the value of attenuation constant then you must calculate distance in metres then convert to cms again. i left everything in cms, and got 3.3 as value of mew, e^-3.3*0.21 gives you 0.5 also.

Reply 1199

mfmdanny

Original post by SS*

Same...I thought it wasn't too bad, but after reading all these posts...maybe not.

I am hoping the grade boundaries are lower than they were in January!