AQA AS Physics A Unit 2 25/05/12 - PHYA2

Original post by Amirrryy

i didnt say you need to work out elastic limit..you can see the linear section of a graph and i said you use that to measure the gradient.

i did it in perspective of a wire but all same things, will I get the marks?

Reply 1263

Amirrryy

1

Original post by sreddy17

i did it in perspective of a wire but all same things, will I get the marks?

I assume you will get most, as hookes law applies to springs and wires...but idk if you will get all since the question specified "For a spring" :L

Reply 1264

Original post by Amirrryy

I assume you will get most, as hookes law applies to springs and wires...but idk if you will get all since the question specified "For a spring" :L

ok thanks!

Reply 1265

Amirrryy

1

you're welcome :smile:

Reply 1266

Original post by RyanGibbard

Oh my days, so many people don't seem to get this....

2 pi = 360
This would mean point X is in the same stage of the wave as point Z if you put 2pi... but it wasn't! It 7/8 the way round the wave!!!!

Jeez calm down...
I didn't say the answer was 2 pi, I simply put they were in antiphase and in phase, because I didn't get taught to do phase difference for stationary waves, simply the points being either in phase or in antiphase with each other. Not my fault I didn't get taught it properly perhaps, our teacher told us phase difference in degrees only applies to progressive waves, and the summary question might involved degrees but there is no mention of it in the text bit either. Just either zero or 180..

I don't think my teacher would be wrong though, or the textbook and revision guides? Why would they ask about the waves which are formning the stationary wave rather than about the stationary wave itself? It doesn't make any sense. The question didn't ask for phase difference either, just the relationship.

(edited 11 years ago)

Reply 1267

Original post by uxa595

and the other page

Anyone get something along these lines?..
Question 5 B
Part i, W = F1 + F2
Extension of any one of the strings..
F=kΔL
W/k=ΔL
7.5/85 = 0.08823529412m
ΔL1 = 0.088m

Part ii , the overall extension was W/K1 + W/K2
Leading to (15/85)+(15/85) = W/K ... Which we know is ΔL
ΔL = 0.3529411765m
ΔL = 0.36m (2.s.f)

Part iii , energy stored in the parallel arrangement --> 0.5ΔLW
however there was 2 springs so 2 x 0.5ΔLW
so E =ΔLW
E=0.08823529412x7.5
E=0.6617647059J
E=0.66J

(edited 11 years ago)

Reply 1268

Original post by Millyshyn

Jeez calm down...
I didn't say the answer was 2 pi, I simply put they were in antiphase and in phase, because I didn't get taught to do phase difference for stationary waves, simply the points being either in phase or in antiphase with each other. Not my fault I didn't get taught it properly, our teacher told us phase difference in degrees only applies to progressive waves, and the summary question might involved degrees but there is no mention of it in the text bit either. Just either zero or 180..

hello, for hooke's law 6 marker i did it in perspective of a wire but all same things,do i think I will get the marks?

Reply 1269

Original post by Kdot

Anyone get something along these lines?..
Part A, W = F1 + F2
Extension of any one of the strings..
F=kΔL
W/k=ΔL
7.5/85 = 0.08823529412m
ΔL1 = 0.088m

Part B , the overall extension was W/K1 + W/K2
Leading to (15/85)+(15/85) = W/K ... Which we know is ΔL
ΔL = 0.3529411765m
ΔL = 0.36m (2.s.f)

Part C , energy stored in the parallel arrangement --> 0.5ΔLW
however there was 2 springs so 2 x 0.5ΔLW
so E =ΔLW
E=0.08823529412x7.5
E=0.6617647059J
E=0.66J

hello, for hooke's law 6 marker i did it in perspective of a wire but all same things,do i think I will get the marks?

Reply 1270

tahseen1995

For the state the phase relationship, would I get 0 marks for saying 135 degrees out of phase and 315 degrees out of phase respectively?

Reply 1271

Original post by sreddy17

hello, for hooke's law 6 marker i did it in perspective of a wire but all same things,do i think I will get the marks?

I don't know, heard of someone experimentally determining Hooke's law being applied to wires because it's the spring constant you're trying to calculate, I don't think doing it with weights up to 20N would actually make it extend much at all. What exactly did you say though? You could still get a few marks even if it's in the wrong context but you've done the right experiment.

Reply 1272

Jammie Dodgers

5

Original post by Kdot

Anyone get something along these lines?..
Question 5 B
Part i, W = F1 + F2
Extension of any one of the strings..
F=kΔL
W/k=ΔL
7.5/85 = 0.08823529412m
ΔL1 = 0.088m

Part ii , the overall extension was W/K1 + W/K2
Leading to (15/85)+(15/85) = W/K ... Which we know is ΔL
ΔL = 0.3529411765m
ΔL = 0.36m (2.s.f)

Part iii , energy stored in the parallel arrangement --> 0.5ΔLW
however there was 2 springs so 2 x 0.5ΔLW
so E =ΔLW
E=0.08823529412x7.5
E=0.6617647059J
E=0.66J

Yeap.

Reply 1273

Original post by Kdot

Anyone get something along these lines?..
Question 5 B
Part i, W = F1 + F2
Extension of any one of the strings..
F=kΔL
W/k=ΔL
7.5/85 = 0.08823529412m
ΔL1 = 0.088m

Part ii , the overall extension was W/K1 + W/K2
Leading to (15/85)+(15/85) = W/K ... Which we know is ΔL
ΔL = 0.3529411765m
ΔL = 0.36m (2.s.f)

Part iii , energy stored in the parallel arrangement --> 0.5ΔLW
however there was 2 springs so 2 x 0.5ΔLW
so E =ΔLW
E=0.08823529412x7.5
E=0.6617647059J
E=0.66J

yeah for part 1 i got that but I said 0.09 , will i get the marks?

Reply 1274

Original post by sreddy17

hello, for hooke's law 6 marker i did it in perspective of a wire but all same things,do i think I will get the marks?

If you mentioned something relating to hook's law and how to measure the constant you probably might just lose a mark, however if you went down the young modulus route you wont be getting anything.

Reply 1275

Original post by Kdot

If you mentioned something relating to hook's law and how to measure the constant you probably might just lose a mark, however if you went down the young modulus route you wont be getting anything.

yes I did, haha no i didn't do young modulus, I talked about measuring extension and force, measure length of the original test wire, etc etc , plotting the graph working out the gradient, but just used a wire instead of a spring. Is that ok then?

Also, for the springs one in parallel did you get 0.09 ?

Reply 1276

Original post by Kdot

If you mentioned something relating to hook's law and how to measure the constant you probably might just lose a mark, however if you went down the young modulus route you wont be getting anything.

Yeah, this. If you did it as if it was a spring but used the wrong word it'll most likely be fine, you'll just lose a mark or two for QWC because of not being coherent. If you did the young's modulus experiement though, you'll get nothing.

Reply 1277

Original post by sreddy17

yeah for part 1 i got that but I said 0.09 , will i get the marks?

You can never know with these AQA mark schemes, but from the figures you have been given (both are 2.s.f) I dont think you should go any less than 2 tbh, but again i am just like you, I've taken the exam.

Reply 1278

Original post by sreddy17

yes I did, haha no i didn't do young modulus, I talked about measuring extension and force, measure length of the original test wire, etc etc , plotting the graph working out the gradient, but just used a wire instead of a spring. Is that ok then?

Also, for the springs one in parallel did you get 0.09 ?

That's absolutely fine then, you'll just lose for QWC.
I think 0.09 is right but I wrote it down to more significant figures than that.

Reply 1279