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AQA A Physics Unit 4 24th Jan 2012

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Reply 81
does anyone have a mark scheme for the exam style ques from the text book ?
Reply 82
also does anyone have the june 2011 paper and mark scheme ?
Original post by mk207
Q. 23


The answer is D,
cuz if you equate mw^2r to Bqv,
according to the question, q=e and m=m obv,
Using v=wr we can cancel v on both sides.
So, mw=Be
then using w=2pi/t
we get 2pim/T = Be
rearrange that to make T the subject and there you go! :smile:
Could somebody explain to me the answer to Q2 June2010
http://idisk.me.com/mail.matt/Public/Sites/egsphysics/files/a_level_past_papers_new/Jun%2010/AQA-PHYA4-1-W-QP-JUN10.PDF

I thought i just had to use "ft=mv-mu" but with that i get 100 not 50.
And Q4 as well thanks
Thanks
(edited 12 years ago)
Reply 85
Original post by handsome7654
The answer is D,
cuz if you equate mw^2r to Bqv,
according to the question, q=e and m=m obv,
Using v=wr we can cancel v on both sides.
So, mw=Be
then using w=2pi/t
we get 2pim/T = Be
rearrange that to make T the subject and there you go! :smile:


that's what i did and i got D but my mark scheme says the answer is B... :confused:
Original post by soldiersixteen
Could somebody explain to me the answer to Q2 June2010
http://idisk.me.com/mail.matt/Public/Sites/egsphysics/files/a_level_past_papers_new/Jun%2010/AQA-PHYA4-1-W-QP-JUN10.PDF

I thought i just had to use "ft=mv-mu" but with that i get 100 not 50.
And Q4 as well thanks
Thanks


You do use the equation Ft = m(v-u)

Ft = Area = (5000*40)/2 = 100,000

100,000 = m(v-u)
100,000 = 2000(v-0)
50 = v

I'm not sure about Q4, sorry.
Original post by schizopear
that's what i did and i got D but my mark scheme says the answer is B... :confused:


I've got that question in a booklet made by my college, and the answer in their mark scheme is D. I agree with handsome7654's working, so it must just be a mistake in the mark scheme.
Reply 88
Original post by jones_wise
I've got that question in a booklet made by my college, and the answer in their mark scheme is D. I agree with handsome7654's working, so it must just be a mistake in the mark scheme.


i thought (hoped!) it might be a mistake - thanks :smile:
How do you do this

The diagram shows two charges, +4 μC and –16 μC, 120 mm apart. What is the distance from the +4 μC
charge to the point between the two charges, where the resultant electric potential is zero?
A) 24mm
B) 40mm
C) 80mm
D) 96mm

Thanks
Reply 90
Original post by soldiersixteen
How do you do this

The diagram shows two charges, +4 μC and –16 μC, 120 mm apart. What is the distance from the +4 μC
charge to the point between the two charges, where the resultant electric potential is zero?
A) 24mm
B) 40mm
C) 80mm
D) 96mm

Thanks


you use the electric potential formula

V=Q/4piepsilon0 x r but the 4piepsilon0 cancels for both so jus ignore it

so for the 4uC you do V=4uC/120 and for the -16uC you do V=-16uC/120-x

equate them and solve for x you should get 24mm :smile:
Original post by kimmey
you use the electric potential formula

V=Q/4piepsilon0 x r but the 4piepsilon0 cancels for both so jus ignore it

so for the 4uC you do V=4uC/120 and for the -16uC you do V=-16uC/120-x

equate them and solve for x you should get 24mm :smile:


Thanks.
When i equate them, I get
480u-4ux= -1920u
-4ux=-2400u
x=600

where am i messing up?
Original post by soldiersixteen
Thanks.
When i equate them, I get
480u-4ux= -1920u
-4ux=-2400u
x=600

where am i messing up?


Do it like this;
Cuz the sum of the potentials at a distance x away from 4uC is 0, you get
+4u/4piepsilon0(x) - 6u/4piepsilon0(20-x) = 0, then add 6u/4piepsilon0(12-x) to both sides,
4u/x = 6u/120-x (the 4piepsilon0 bit cancels), then multiply by (120-x)
480u - 4ux = 16ux
so x = 480u/20u = 24mm! :smile:
Reply 93
Original post by mk207
Q. 23


Hi I got the answer of D, is it possible for you to upload a markscheme for these questions if yuo have one? Thanks
Reply 94
Original post by savage903
Hi I got the answer of D, is it possible for you to upload a markscheme for these questions if yuo have one? Thanks


there you go
Reply 95
I have just spent all day printing off every multi choice question from the past 10 years. Highligting the right answer and cutting them out. Then placing them in 7 piles (pile for each topic). After removing recent questions and questions that have already been repeated once I think I can guess a few of out questions, well the ones they will be re-using anyway.
Reply 96
can you put them up ???
Original post by maths134

Original post by maths134
I have just spent all day printing off every multi choice question from the past 10 years. Highligting the right answer and cutting them out. Then placing them in 7 piles (pile for each topic). After removing recent questions and questions that have already been repeated once I think I can guess a few of out questions, well the ones they will be re-using anyway.


could you PM them please to me? :smile: :smile:
Original post by maths134
I have just spent all day printing off every multi choice question from the past 10 years. Highligting the right answer and cutting them out. Then placing them in 7 piles (pile for each topic). After removing recent questions and questions that have already been repeated once I think I can guess a few of out questions, well the ones they will be re-using anyway.


Can I ask how you got access to all those past papers? If there is a website for them, can u give me the link plzz?? Really need some practice cuz iv only been getting C/Ds on my practice papers!! :mad:
Reply 99
If you guys want to spend a day working it out, you welcome to...

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