AQA Physics A Unit 4- 11 June 2014

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Original post by Maloneyyy

I used the sun as M and the Earth as m

What about r? It should be 10^11 because it's km.

Reply 781

M8976

I can never do these questions with point charges or with gravitational where you have to find where the force is zero, could anyone tell me how to do it?

Reply 782

cem101

11

Original post by dudesamld

It would be pretty mean for them to ask but take a look at this : http://tap.iop.org/vibration/shm/306/page_46606.html
its a lesson plan on the experiment

how come in water its light damping but in oil its heavy damping?

Reply 783

Original post by Rock_Set

It says the 'conductor'. Read the examiners report for the love of the god.

Sorry, I got it wrong.

Who the **** reads the examiner's report?

Reply 784

Rock_Set

Original post by BigBadJFly

Sorry, I got it wrong.

Who the **** reads the examiner's report?

People who want model answers for the 6 markers lol

Reply 785

Original post by GeekChic7

Okay, either revision has got to me more than I thought or I'm going blind, but I can't see it saying anywhere about an EMF in the rod? I can only see it about an EMF in the ring?

D'oh, sorry my bad. Just as well I told you what paper it was :biggrin:

Reply 786

GeekChic7

Original post by BigBadJFly

Sorry, I got it wrong.

Who the **** reads the examiner's report?

So no EMF in the rod then?

Sorry, no, we're good :')

Reply 787

YOOZERNAYME

Original post by YOOZERNAYME

Anyone know how to do Q2? ImageUploadedByStudent Room1402431228.044640.jpg

Posted from TSR Mobile

bump

Reply 788

Original post by Rock_Set

People who want model answers for the 6 markers lol

I got 5/6 marks on it, and usually get 6/6.

I got 8 marks into an A*, and I've never read an examiner's report for physics :s-smilie:

Reply 789

Maloneyyy

Original post by Rock_Set

What about r? It should be 10^11 because it's km.

Oh yeah, just tried that but it still doesn't work

Reply 790

Keeks52

Does anyone know if we need to understand back emf? Please say no

Reply 791

Plmnko543

Original post by YOOZERNAYME

Anyone know how to do Q2? ImageUploadedByStudent Room1402431228.044640.jpg

Posted from TSR Mobile

As T is proportional to root L and if T is halved then L must have been divided by 4. As you would be left with a quarter of L, then by taking away 600mm is the same as taking away 3/4L. So 600 = 3L/4 Rearranging gives L=800.

Reply 792

Original post by cem101

how come in water its light damping but in oil its heavy damping?

Oil is presumed to be more viscous than water, so provides greater resistance :smile:

Reply 793

ambonkers

Hello, can someone please explain this Q to me, thanks :smile:

Fullscreen capture 10062014 212032.bmp.jpg

Reply 794

lebron_23

Original post by YOOZERNAYME

Anyone know how to do Q2? ImageUploadedByStudent Room1402431228.044640.jpg

Posted from TSR Mobile

Set up your equation for T at the original length.

T=2\pi \sqrt \dfrac{l}{g}

.

Then, if the time period is halved and

l

is reduced by

600 \times 10^{-3}

\dfrac{1}{2}T=2\pi \sqrt \dfrac{l-600 \times 10^{-3}}{g}

.

Then, multiplying through, substituting for T and cancelling

l=4l-2.4

.

I think that gives the answer as A, couldn't tilt my head far enough to see :tongue:

.

(edited 9 years ago)

Reply 795

Joewa12

Original post by lharris

At least we can be sure its not that then!!

Id prefer that to induction hahaah

Reply 796

lebron_23