* Physics HL 2011 * HL predictions / discussion / aftermath * (1 thread only please)

Stretch101

Ya 4/3 F is right!

sparagon

Ahhhh is 4/3 F really right\/ i got that but i assumed i was wrong. When they touched did they both have the charge 2Q?

jamesr1775

yea

owenthorp7

I think the paper was fair. The section A allowed you to build up a lot of marks to nearly pass you. Section B was fair, it was not simple or impossible as long as you studied decent enough for it. After being so pissed off at the SEC for honours maths paper 1 I have to say that this exam was an ideal one to prove your knowledge of a subject!

yannfann

Decent paper, if you knew your stuff you were fine.
That said there was definitely a few tricky questions, hoping for a b1/b2 now!

DM360

Brian123M wrote: »

Whats the experiment to show the same thing as the worker with the suit of metal around him to protect him from the electricity

Same principle as the Faraday cage. You could have done the one with the can on the Van de Graaff generator showing charge only resides on the outside of a hollow conductor

irish_man

for 12(A) was it not F=mg-ma for the minimum and F=ma+mg for the maximum??

Sparticle

I thought that the exam was quite challenging.


Q7 was a bit iffy.

Did anyone else say radiation( by infrared from cup)(Solved by the colour white) and conduction with cup (Solved by insulating material) for Q7 b?

Did anyone else create an elaborate two beakers, two calibrated thermometers and one thermocouple set-up for Q7c?

I think they're right in theory but do you think I'll get any marks for them?

jumpguy

In depth...

Q2 - Lovely, and I predicted it! Take that, stupid mocks.

Q3 - Lovely, almost easier than previous years.

Q4 - One again, lovely. Got 29 Ohms or something (can't quite remember) for resistance.

Q5 - Straight-forward.

Q7 - In the (a) part I got the heat change of steam wrong (took initial milk temp from initial steam temp, apparently this is wrong according to a friend after). Hopefulyl that won't cost me more than 6 marks at most though.

Q8 - Grand out, straight-forward enough.

Q10 - Lovely, got the energy for both the colliding protons and halved it at the end to get 130 MeV or whatever it was, hope I'm not penalised since I shoulda used E=mc^2 and not E=2mc^2

Q12 - Did (c) and (d). (c) required some thought but was overall fine, (d) was also fine.

I wasn't happy about the lack of nuclear physics on the paper, but overall I thought it was fair enough and adequately challenging for a HL paper.

B_Fanatic

The fcuk? I thought the paper was a little harder than usual, but nothing crazy like maths paper 1. But Q7 A, A metal spoon is then placed in the hot drink causing the temperature of the hot drink to drop... What the hell is the mass of the spoon???

Digits

jamesr1775 wrote: »

anyone else get 4/3 F for first part of question 9?

Yeah I'm still not too sure about it though seemed a little too easy for 18 marks.

But yeah I got that answer.

Fairly nice paper overall IMO.

Gyaradose

Section A
Q1C.l.m. was lovely
Q2Boyles law was different but i think i answered it correctly
Q3wavelenght of light was ok, not sure if I got all of the first part right but for the second part I got, less order images, more order images and infinite order images as it undergoes dispersion.

Section B
Q5 was a beauty, so easy, knew all 10 parts
Q6 was grand, see saw and part a were junior cert suff, c on the other hand was tricky but a few friends and I got 0.83 or summit like that for the angular velocity
Q7 was grand until I realised I have no clue what a thermocouple is, that is a little bit of a downside
Q8 not sure about the destructive interference part, can someone help me with that? Everything else was grand
Q9 was simple and this is coming from someone who disregarded electricity after the mock. Coulomb's law was handy and I got 4/3 F. Electroscope was basic too, not sure about why it is earthed though, or at least what the marking scheme is looking for. Part C was easy, charge resides on the outside and then the van der graaf generator experiment.
10 A was also easy except I had no time to do the final part
12 A + B also basic stuff, minimum force was 0 as when it's at the centre s=0 so a=0 and finaly f=0, applied amths for the mother-f*cking win!
And B was handy, I do love a nice bit of snell's window

cbaa

does anyone know the answer to 5a, the force? i couldn't get it

deiseguuy93

i was very happy with the paper over all the experiments were very easy! I'm trying to mark myself now so i have a rough idea what i got! is anybody going to put up a solution for this as they did for maths HL?

Especially that 6(c) i would like to know if i got that right!

Gyaradose

B_Fanatic wrote: »

The fcuk? I thought the paper was a little harder than usual, but nothing crazy like maths paper 1. But Q7 A, A metal spoon is then placed in the hot drink causing the temperature of the hot drink to drop... What the hell is the mass of the spoon???

Heat capacity is the amout of energy required to change the temp of a body by 1 degree

Specific heat capacity is the amout of heat energy required to change the temp of 1kg of a substance by 1 degree

Take a guess at what they asked for...

yannfann

B_Fanatic wrote: »

The fcuk? I thought the paper was a little harder than usual, but nothing crazy like maths paper 1. But Q7 A, A metal spoon is then placed in the hot drink causing the temperature of the hot drink to drop... What the hell is the mass of the spoon???

You werent asked for the specific heat capacity, which you would need the mass for, just the heat capacity, so you disregard mass in the mc(rise in temp) for the spoon!

Gyaradose

cbaa wrote: »

does anyone know the answer to 5a, the force? i couldn't get it

6000 newtons i think

jamesr1775

cbaa wrote: »

does anyone know the answer to 5a, the force? i couldn't get it

not sure if im right but i worked out the acceleration with linear motion equations then applied f=ma

deiseguuy93

cbaa wrote: »

does anyone know the answer to 5a, the force? i couldn't get it

find the de-acceleration then put it in to F=MA as a positive value

Hollzy

What the hell is the mass of the spoon???[/QUOTE]

That caught me out..... It reminded me of the Biology paper in a way. I liked the Biology paper because I think it challenged your understanding of the subject. The difference is I adore Biology, I hate Physics. I've always struggled with Physics but my teacher has helped me out and he said he really wanted me to scrape a B3. I didn't but I got my C which I was expected myself I think.

I liked the experiments, I did Q1, Q2 and Q4. Section B I wasn't crazy about. I love heat, it's my best section but I know I really messed up that question. I thought Q5 was quite good and I was pretty happy with the particle question. I'm not a big Mechanics fan but I did it as my last question and it went better than I'd expected. I thought Q12 was tough enough, I did (a) and (d), but didn't finish (a). Timing was a bit of an issue but I managed to finish it.

Oh, one thing that's bugging me... What constant is named after Robert Mellikan (or something like that! I don't think I've ever heard of him!)

irish_man

B_Fanatic wrote: »

The fcuk? I thought the paper was a little harder than usual, but nothing crazy like maths paper 1. But Q7 A, A metal spoon is then placed in the hot drink causing the temperature of the hot drink to drop... What the hell is the mass of the spoon???

You didn't need it. I was c=(mass of hot drink x 2 K) / 48 K

It asked for heat capacity not specific heat capacity. heat capacity doesn't require mass.

Stretch101

Gyaradose wrote: »

Q6 was grand, see saw and part a were junior cert suff, c on the other hand was tricky but a few friends and I got 0.83 or summit like that for the angular velocity

Sounds familiar!!!

deiseguuy93

applied maths did come in very handy throughout the paper!

Gyaradose

After getting raped by maths I find It highly satifying to be the rapist once again........... bring on Applied maths.

cabbage kid

Oh, one thing that's bugging me... What constant is named after Robert Mellikan (or something like that! I don't think I've ever heard of him!)

He measured the charge on an electron.

Hollzy

cabbage kid wrote: »

He measured the charge on an electron.

Oh cool, I threw down something like that as a guess =D

B_Fanatic

irish_man wrote: »

You didn't need it. I was c=(mass of hot drink x 2 K) / 48 K

It asked for heat capacity not specific heat capacity. heat capacity doesn't require mass.

... I honestly did not have the slightest idea there was a difference between the two.... Kind of pissed that no one brought it to my attention earlier (Especially my teacher.)

Gyaradose

What was the diagram for the merry go round and twhat would happen without friction too? I got friction as the centripetal force or summit and sai the child would fall off without friction :L

sh1tin-a-brick

deiseguuy93 wrote: »

applied maths did come in very handy throughout the paper!

I didnt think so! I was really hoping for a nice mechanics question like the skateboarder one in 2009. Applied maths made it piss easy! No such luck though . To be fair, we dont do the circular motion question in app maths so I only used a tiny bit here and there.

I didnt like this paper much atal tbh, but then again, physics is like my geography, I just do it cos I had to do another subject :rolleyes: . The experiments were lovely though! I think I did ok despite my lack of effort over 2 years!

Hah, started teaching myself the option at half nine last night, still got have of the question on it! Such an easy and interesting topic, dont know why my teacher didnt do it with us.

Stretch101

Gyaradose wrote: »

Oh, one thing that's bugging me... What constant is named after Robert Mellikan (or something like that! I don't think I've ever heard of him!)

The electric charge of an electron