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OCR Physics A G485 - Frontiers of Physics - 18th June 2015

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Reply 1600

jcwh97

Original post by Help_Me_Alex

did you get that with P = (T^4) x (r^2) ?

Yes exactly that

Reply 1601

Elcor

Original post by Leechayy

Multiply by 0.01 as only 1% is actually applied to the photon

Posted from TSR Mobile

No it's .99 because that's the amount that goes into heat.

Posted from TSR Mobile

Reply 1602

username1385543

Original post by L'Evil Fish

Just wait for teachercol!

I did get 5cm ish

how long do you reckon teachercol will be?

Reply 1603

L'Evil Fish

Original post by Genty Boy

Agreed, but I made it 36%. I may have RTQ wrong...

Posted from TSR Mobile

It said transmitted into bone

36% is amount reflected, so it's just 1-it

Reply 1604

SH0405

Original post by BrokenS0ulz

13.4 activity
64% transmitted ultrasound
1.8x10^-3 average current
520 Ks^-1 for the heating thing
16 for ratio of ke
?

I think the transmitted ultrasound should be 36%.

Edit: Oh, it said transmitted :frown:

Reply 1605

seizetoday

Original post by BrokenS0ulz

It was asking for the heat energy transferred ?

Nah it didn't. You x by 0.1 because it that's the energy to the photon or something

Reply 1606

Elcor

0.051m
1340 Bq
1.8x10^-3 A
2.0x10^7 for something
4.7x10^-15 for something
7.92x10^6 for something
592 rate of temp
1st ratio 9.0x10^-15
2nd 1.06x10^7

Reply 1607

jcwh97

Original post by seizetoday

Nah it didn't. You x by 0.1 because it that's the energy to the photon or something

That was for the second part with the wavelength. The first part you had to multiply by 0.99 it had nothing to do with the photon.

Reply 1608

Sam_Roper

Ffs I misread cat Scan as pet scan.

At least I'll get 2/5 for talking about 360 degree detectors and computer converting signal to image.

I messed up a few questions. Don't listen to anyone on TSR about grade boundaries. It wasn't an easy paper. It wasn't the hardest, but it was no easy. My prediction would be roughly 70 for an A and 78 for an A*.

Reply 1609

Elcor

For the minimum wavelength you don't times by any factor because it's when all the KE of an electron goes into an X ray. Got 10^-12 something.

Reply 1610

Sam_Roper

Original post by Genty Boy

Agreed, but I made it 36%. I may have RTQ wrong...

Posted from TSR Mobile

I also did this

Reply 1611

Elcor

Kinetic energy ratio was 16, % was 64%

Reply 1612

IAmYourdog

Original post by matthew6665

what the **** are you smoking ? 80% of people that i know did this exam said it was well harder than usual. Last year's was much easier...
Don't base grade boundaries on people from TSR , cause most people here are like A* candidates lol. I am sure that paper will not be more than 72 for an A.

LOL QUOTED THE WRONG PERSON. SORRY. BUT ANYWAY...

Well I highly disagree with it being harder than last years. I'd say it was a little easier.

Reply 1613

BrokenS0ulz

Original post by Elcor

0.051m
1340 Bq
1.8x10^-3 A
2.0x10^7 for something
4.7x10^-15 for something
7.92x10^6 for something
592 rate of temp
1st ratio 9.0x10^-15
2nd 1.06x10^7

Agreed with all except 13.4 for activity. And I cant remember if I got the4.7 one or the 7.92.

Reply 1614

Devran22

Original post by Genty Boy

Agreed, but I made it 36%. I may have RTQ wrong...

Posted from TSR Mobile

I got 36 to!

Posted from TSR Mobile

Reply 1615

SH0405

Grade Boundary Predictions:

100% UMS: 87
90% UMS: 79
A: 71
B: 64
C: 56
D: 49
E: 42
U: 0

Reply 1616

kateyl

Ughh I messed up on the one where you had to find the horizontal displacement of the falling powder stuff :frown:

changed my answer last minute. I didnt use speed=distance/time with the terminal velocity and ended up using suvat to find time, would I have lost one mark for that? or more? :frown:

Reply 1617

Elcor

Why would you even do a grade boundary prediction like it's totally ambiguous for you and depends on the entire student cohort (which TSR does not represent)