**Physics...Before/After**

Epsi

finality wrote: »

the length of the string (a very short length results in a high percentage error) and the angle the pendulum oscillates through

This is what I said as well.

BrianC2095

Wesc. wrote: »

Yeah so did I.. that was sly enough alright. Feck it anyway! Still, I do think I got an A1.

Actually i just checked it and it seems like its just the nucleus masses that are given in the tables of nuclides the mass of a deuterium is 3.3444x10^-27 and the mass of a proton and neutron seems to be 3.3498x10^-27 so it looks like it doesnt matter ?

MauraTheThird

Astrozombies wrote: »

"What are the three conditions for an observer to see a rainbow?"

what even was that.. I said rainfall, dispersion of polychromatic light and .. clear skies? :P

I said having eyes and my teacher laughed at me

mathstalk

So many badly phrased questions in the paper. Very unscientific.

Tankosaur

MauraTheThird wrote: »

I said having eyes and my teacher laughed at me

I'm sorry sir they may not accept that, blind people have eyes and can't see :L

But yeah it was a stupid question.

COnditon 1) look at the sky.... etc etc.

finality

I wish they would put the paper up... I don't think I got less than a B1 but I want to put my mind at rest

Kakes

subz3r0 wrote: »

In the question it said nuclei i.e. without electrons. Tables have them including electrons.

damn i just realised this too. curious though, even if you did use those masses and they include the mass of the 2 electrons, when you take away the mass of the helium nucleus and the neutron to find the mass defect, would they not cancel out?

ei.sderob

Question 8 was tricky alright, I converted the masses all to u's and then worked out the energy produced then. Looking back on it I'll probably lose 3 marks as a blunder as I should've converted all to Kg's instead. Hoping for the A1. What did ye do for the force of repulsion for the last part of 8? I used Coulombs law and said the charges of both nuclei were 1 and then converted the nanometers to metres and subbed into the formula. Not sure if it's 100 percent right like with the charges being 1. It's a pretty good guess though.

finality

ei.sderob wrote: »

Question 8 was tricky alright, I converted the masses all to u's and then worked out the energy produced then. Looking back on it I'll probably lose 3 marks as a blunder as I should've converted all to Kg's instead. Hoping for the A1. What did ye do for the force of repulsion for the last part of 8? I used Coulombs law and said the charges of both nuclei were 1 and then converted the nanometers to metres and subbed into the formula. Not sure if it's 100 percent right like with the charges being 1. It's a pretty good guess though.

Pretty sure the charges should have been 1.6x10^-19

but you'd probably only lose 3 marks for that

Kakes

ei.sderob wrote: »

Question 8 was tricky alright, I converted the masses all to u's and then worked out the energy produced then. Looking back on it I'll probably lose 3 marks as a blunder as I should've converted all to Kg's instead. Hoping for the A1. What did ye do for the force of repulsion for the last part of 8? I used Coulombs law and said the charges of both nuclei were 1 and then converted the nanometers to metres and subbed into the formula. Not sure if it's 100 percent right like with the charges being 1. It's a pretty good guess though.

i did the same except i guessed that the nucleus of both atoms had one proton each, so i used the value for the charge on the electron (because i think it is the same)

BrianC2095

ei.sderob wrote: »

Question 8 was tricky alright, I converted the masses all to u's and then worked out the energy produced then. Looking back on it I'll probably lose 3 marks as a blunder as I should've converted all to Kg's instead. Hoping for the A1. What did ye do for the force of repulsion for the last part of 8? I used Coulombs law and said the charges of both nuclei were 1 and then converted the nanometers to metres and subbed into the formula. Not sure if it's 100 percent right like with the charges being 1. It's a pretty good guess though.

I did the same thing but i think it was supposed to be in coulombs which is the charge on the proton :rolleyes:

ei.sderob

finality wrote: »

Pretty sure the charges should have been 1.6x10^-19

but you'd probably only lose 3 marks for that

3 marks is grand. I think 8 was my worst question. It was the trickiest on the paper in my opinion.

finality

ok, the charge on the proton is definitely 1.6x10^-19

it says it in real world physics, page 229 q7

tacofries

Tankosaur wrote: »

May I ask what people answered for the question on diffraction of x-rays? I said that they will be diffracted but not to the same extent as light as their wavelenghts are very different.

I didnt do it but i would say the diffraction grating wouldnt diffract x-rays as x-rays would pass straight through the material of the grating like they do when taking x-rays of bones, machines etc.

HeaneyBabe

That was so easy. Definitely got the A1.

kiwimad

Was hoping for an A2 but after reading through this thread I think I'm down to a B1. I did Q11 but just realised I'd have got more marks doing Q9. Very annoyed with myself now! Ah well it's just chemistry left now and I'm not counting that so IT'S (nearly) SUMMER!

shefellover93

Few, what a relief! Did 6 questions in the Section B (OL) and they all went ok Should do enough to pass which is all I want anyways, just one more to go now! :pac:

checkcheek

What did people do for the option question. I had no clue about the maths

nmd64

I used 2mc^2 = 2hf

How do you do question 6? I made a balls of it but had time to do an extra question, but I'm still curious as to how to work out the final parts, roughly.

Worried about question 5 since I was relying on full marks in it but there were a few tricky ones, what did people say for the rainbow and cigarette smoke questions?

I said Cockcroft instead of Walton so I really hope those weird ones get marked loosely ><

iLaura

nmd64 wrote: »

I used 2mc^2 = 2hf

How do you do question 6? I made a balls of it but had time to do an extra question, but I'm still curious as to how to work out the final parts, roughly.

Worried about question 5 since I was relying on full marks in it but there were a few tricky ones, what did people say for the rainbow and cigarette smoke questions?

I said Cockcroft instead of Walton so I really hope those weird ones get marked loosely ><

I did even better; I wrote down both Cockcroft and Walton :P

AVA_Steve

Was anybody else not told by their examiner that they had to hand up the paper? I asked, and she just told me to regraph the question on graph paper and hand that up and take the paper home, she said she hadn't received instructions for otherwise so... Am I screwed?

RedTexan

AVA_Steve wrote: »

Was anybody else not told by their examiner that they had to hand up the paper? I asked, and she just told me to regraph the question on graph paper and hand that up and take the paper home, she said she hadn't received instructions for otherwise so... Am I screwed?

I did all the experiment questions just in case! Was very happy with it, but forgot to answer one part of the question 11 (was simple), so that's 7 marks gone. Reckon I should be safe enough with the rest of the paper though! That and all my accounts balanced, was a good day!

iLaura

AVA_Steve wrote: »

Was anybody else not told by their examiner that they had to hand up the paper? I asked, and she just told me to regraph the question on graph paper and hand that up and take the paper home, she said she hadn't received instructions for otherwise so... Am I screwed?

Nope; we got our examiner to ask the principle to ring the SEC, it was a misprint about doing the graph on the paper, so the 15 marks are going for finding the acc. I redrew it out too, if it's any consolidation :P

AVA_Steve

iLaura wrote: »

Nope; we got our examiner to ask the principle to ring the SEC, it was a misprint about doing the graph on the paper, so the 15 marks are going for finding the acc. I redrew it out too, if it's any consolidation :P

So wait we had to do it on the paper? Or? Also fairly sure I screwed up the parachute question, no matter what I did for the value of g, 31k above the earths surface it didn't come out anywhere close to what it should be.

iLaura

AVA_Steve wrote: »

So wait we had to do it on the paper? Or? Also fairly sure I screwed up the parachute question, no matter what I did for the value of g, 31k above the earths surface it didn't come out anywhere close to what it should be.

No, you didn't have to do it on the paper :P I know that some people included their paper in the answer booklet though.

AVA_Steve

Well thank f**k for that, had myself worried sick all afternoon, got chemistry tomorrow and I'm sincerely hoping no misprints. But yeah, physics was ok, definitely didn't do as strong as I would have liked, but then again, when you spend half the year complaining to the Dept of education about your teacher you don't tend to get the best preparation in. Our physics teacher was inspected and everything and found unsatisfactory but our school wouldn't dismiss her, it was mind blowing, we had a substitute teacher who managed to teach us centripetal force in a half an hour class, and she could barely explain the specific latent heat of fusion of ice.

RedTexan

What did people get for the value of the frequency in question 10 somewhere are 1.2 to 1.3 by 10^20?

kaet

RedTexan wrote: »

What did people get for the value of the frequency in question 10 somewhere are 1.2 to 1.3 by 10^20?

Yes! looked about right too I thought.
Anyone know a definite answer for the last part "Why will two positrons not annihilate?" or something? Is it to do with charge not being conserved..?

Wesc.

kaet wrote: »

Yes! looked about right too I thought.
Anyone know a definite answer for the last part "Why will two positrons not annihilate?" or something? Is it to do with charge not being conserved..?

Yeah I said the same, made sense.

RedTexan

kaet wrote: »

Yes! looked about right too I thought.
Anyone know a definite answer for the last part "Why will two positrons not annihilate?" or something? Is it to do with charge not being conserved..?

That's what I said, then I said when they collide their excess kinetic energy will form new particles instead.