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OCR Physics A Breadth of Physics (24th May 2016) Discussion

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I found it a strange paper all in all, I looked at the clock and all my time had gone just as I began to feel like I was getting warmed up. and it seemed very short, probably just lost track of time Pretty sure I failed all/most the calculations I was super stressed out.

(edited 7 years ago)

Reply 321

mxhxs_101

Original post by WhizzKidhehe:)

I made some stupid mistakes for multiple choice like the second one: Work done against gravity- I used perpendicular distance thinking it was moments but it was in the direction of force... damn.

But overall, i think Ive done alright, not too bad

how about you?

I have failed that test so badly! I didn't know how to approach the questions because they weren't making any sense to me. I predict that I got an E

Reply 322

voltz

For the pressure question with the cylinder was I write to say you can use Newton's third law and so find the cross sectional area and weight of the cyclider and sub that into the pressure equation (force/cross sectional area)?

Reply 323

julesaquilina

Original post by RiahDawson

Does anyone remember the multiple choice uncertainty question? It was like +- 0.1 and +-0.4? What was the rest of the numbers?

i think i put 6.5

Reply 324

Shva

Original post by chenhao96

a mcq about voltage halved what happen to the velocity of the electron

U/root2

Because eV=1/2mu^2

V Proportional to u^2

V is halved so works out as U/root2

That was my reasoning anyway

Reply 325

voltz

Original post by sddsfsdafs

Same, how many silly mistakes do you think you made? I know I made a few marks worth and have probably lost marks elsewhere (e.g. how to get that third mark for the LED question)...

I think I got the LED one completely wrong, I said the threshold voltage was too low and connect it in parallel? I was just guessing at that point

Reply 326

tookyourusername

Original post by julesaquilina

i think i put 6.5

I think that's correct. I put 2.5 because I thought you have to minus the uncertainties when dividing, but it's plus. :/

Reply 327

voltz

Original post by Shva

U/root2

Because eV=1/2mu^2

V Proportional to u^2

V is halved so works out as U/root2

That was my reasoning anyway

I put root2(u) since your answer would give a larger answer wouldnt it? Where as root2 multiplied by u will be smaller??

Reply 328

Parhomus

Original post by sddsfsdafs

Same, how many silly mistakes do you think you made? I know I made a few marks worth and have probably lost marks elsewhere (e.g. how to get that third mark for the LED question)...

I think I might have lost a mark because I forgot to say the emf for the led maybe was too low. I talked about polarity, maybe I lost a bit in the one about the force on the asteroid because I crossed out the bit where I wrote in the opposite direction but drew a reflection of the graph. A couple multiple choice and forgetting to divide by two for acceleration.mostly only losing one mark ;(. But it was good.

Reply 329

JAFF2400

Original post by Shva

U/root2

Because eV=1/2mu^2

V Proportional to u^2

V is halved so works out as U/root2

That was my reasoning anyway

I picked u/root 2 without any reasoning thought it looked nice to be honest, i hope its correct lool.

Reply 330

chenhao96

Original post by Shva

U/root2

Because eV=1/2mu^2

V Proportional to u^2

V is halved so works out as U/root2

That was my reasoning anyway

i also find v is proportional to u^2 so when v halved u is root2u

Reply 331

TheHobbit

Original post by WhizzKidhehe:)

I got that but now I'm starting to doubt it because it seemed too easy

I thought it was 0.8/0.2 = 4 because it was the ratio between the smaller diameter/the larger one and a thinner wire will extend more so will have greater epe (so it must be greater than 1)

Reply 332

Ecniwoh

Anyone know the total marks for the last 2 questions?

Reply 333

Parhomus

I doubt 54 would be an A because it's new spec and also because that would mean it's only two marks less than 80%. When usually an A in physics is around 70. I mean for the practice paper ocr had I got mid 50s which was top three in the year (well performing school) and in the top set class most people averaged 35/70.

Reply 334

JAFF2400

I personally think depth in physics is gonna be easier not just because of the exam itself but the fact that I have weeks to revise for it. Todays paper I didn't even touch module 4 could only revise module 3. module 4 itself should be a subject alone. I'm pretty confident i got a U today

Reply 335

Shva

Original post by voltz

I put root2(u) since your answer would give a larger answer wouldnt it? Where as root2 multiplied by u will be smaller??

Root2= 1.414

So >1

So I thought itd get smaller? Since its greater than 1?

Reply 336

mahmzo

Original post by chenhao96

i also find v is proportional to u^2 so when v halved u is root2u

yeah I got the same, I was about to write the 4u but remembered it was the opposite way around

Reply 337

esfio

For the last question, I didn't point out the polarity of the L.E.D., how many marks do you reckon I'd get for mentioning the e.m.f. being too low so use another cell as well as put the resistor parallel to the L.E.D instead of in series?

Reply 338

rafiuddin

Original post by TheHobbit

I thought it was 0.8/0.2 = 4 because it was the ratio between the smaller diameter/the larger one and a thinner wire will extend more so will have greater epe (so it must be greater than 1)

didn't the equation they give have thinner wire on top?

Reply 339

chenhao96

Original post by TheHobbit

I thought it was 0.8/0.2 = 4 because it was the ratio between the smaller diameter/the larger one and a thinner wire will extend more so will have greater epe (so it must be greater than 1)