AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

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Nope lol, unfortunately not. When people ask questions on the thread I just quickly grab a pen and paper and post my workings :smile:

sorry!

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Oh wow thanks dude i didn't know you did that! You seem really confident for the exam :smile:

Reply 2501

_Caz_

Original post by CD223

I swear that's illegal.

(It's not, but you know what I mean :tongue:

)

I think the stress/strain topic is worth revising along with waves from last year as they seem to come up in SHM questions in the past.

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Stationary waves too 0.0 because stationary waves are resonance. Sh*t

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Reply 2502

CD223

Original post by SuperMushroom

Oh wow thanks dude i didn't know you did that! You seem really confident for the exam :smile:

No problem! Helps me go over questions as well - I like it :smile:

I'm definitely not confident though :tongue:

never confident with exams. I always get nervous and make mistakes :frown:

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Reply 2503

CD223

Original post by _Caz_

Stationary waves too 0.0 because stationary waves are resonance. Sh*t

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Yeah stationary waves and fundamental nodes came up in a previous paper which worried me. I know it was only a couple of marks but it hit home how much I've forgotten from AS.

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Reply 2504

_Caz_

Original post by CD223

Yeah stationary waves and fundamental nodes came up in a previous paper which worried me. I know it was only a couple of marks but it hit home how much I've forgotten from AS.

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Lambda/2 is the length of the wire/string right? I think I saw that somewhere on a question...

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Reply 2505

SuperMushroom

Original post by CD223

No problem! Helps me go over questions as well - I like it :smile:

I'm definitely not confident though :tongue:

never confident with exams. I always get nervous and make mistakes :frown:

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I'm sure you'll be ok! If you have a moment could you explain question 12 on that same paper please :biggrin:

Reply 2506

CD223

Original post by _Caz_

Lambda/2 is the length of the wire/string right? I think I saw that somewhere on a question...

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For a fundamental node,

\frac{\lambda}{2} = l

where l is the length of the string.

For the second overtone/first harmonic, the length of the string equals lambda.

It goes like this:

ImageUploadedByStudent Room1433443400.675402.jpg

ImageUploadedByStudent Room1433443400.675402.jpg

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Reply 2507

_Caz_

Original post by CD223

For a fundamental node,

\frac{\lambda}{2} = l

where l is the length of the string.

For the second overtone/first harmonic, the length of the string equals lambda.

It goes like this:

ImageUploadedByStudent Room1433443400.675402.jpg

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Ah okay. The next would be 3/2 lambda then? (For the third overtone)

Thank you so much for clearing that up

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Reply 2508

CD223

Original post by SuperMushroom

I'm sure you'll be ok! If you have a moment could you explain question 12 on that same paper please :biggrin:

ImageUploadedByStudent Room1433443719.295452.jpg

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Reply 2509

CD223

Original post by _Caz_

Ah okay. The next would be 3/2 lambda then? (For the third overtone)

Thank you so much for clearing that up

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Yeah it goes up in intervals of lambda/2 :smile:

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Reply 2510

SuperMushroom

Original post by CD223

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Thats question 13 mate, the one i dont understand is 12

Reply 2511

CD223

Original post by SuperMushroom

Thats question 13 mate, the one i dont understand is 12

Lol, going absolutely mad.

ImageUploadedByStudent Room1433445211.702504.jpg

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Reply 2512

SuperMushroom

Original post by CD223

Lol, going absolutely mad.

ImageUploadedByStudent Room1433445211.702504.jpg

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Could you explain what you have done on the 3rd line down please?

Reply 2513

CD223

Original post by SuperMushroom

Could you explain what you have done on the 3rd line down please?

• The ratios of gravitational field strength equals the ratio of the masses divided by the ratio of the radii squared.

• the mass is proportional to the product of the density times volume, and hence proportional to the density times radius cubed:

• The ratios of gravitational field strength equals the ratio of the densities multiplied by the ratio of the radii cubed divided by the ratio of the radii squared.

Cancelling top and bottom (cubed and squared terms):
• The ratios of gravitational field strength equals the ratio of the densities multiplied by the ratio of the radii.

• Dividing the ratios of gravitational field strength by the ratio of the densities gives 6 divided by 5/3 which is 3.6.

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Reply 2514

sykik

Are we allowed to use Extra paper for multiple choice?

Reply 2515

oonic0rn

http://filestore.aqa.org.uk/subjects/AQA-PHYA4-2-W-QP-JAN11.PDF

could anyone explain question 3a its straight over my head :colondollar:

EDIT- not as bad as it looks when looking at the mark scheme, i was just over complicating it thinking about the resistor and capacitor discharge!!

(edited 8 years ago)

Reply 2516

theoriginalrpr

any predictions for this paper?

Reply 2517

a.a.k

Original post by theoriginalrpr

any predictions for this paper?

Lots of physics

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Reply 2518

sykik

Can anyone explain why racing tracks are bunked in terms of centripetal force.

Reply 2519

Lau14

Original post by sykik

Are we allowed to use Extra paper for multiple choice?

I can't see why not, but as the answers for the multiple choice go onto a separate sheet you can write all over and around the questions for that section :smile: