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# AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] watch

1. [QUOTE=Billsonbubbles;64557167]
(Original post by boyyo)

Ahah no worries

Just to be clear though you can calculate angular velocity = 2Pi / T

Where T is the time period and as they both have the same time period they both have the same angular velocity.

Your equation of V being = 2Pi x radius / Time period is the speed on the perimeter is NOT ANGULAR SPEED.

Sorry to put that in caps .... it was just so it is made clearer ,

and my teacher agrees with on my points... so it should all be correct.

Good luck again for the exam ,

Will
Ohh yeahh, also v is linear speed, so it doesnt make sense using that right? Thanks for you help and tell your teacher I said thanks too lol.
2. 2015 papers are now available on aqa's website http://www.aqa.org.uk/subjects/scien...d-mark-schemes
3. how so you solve this question

Initially a charged capacitor stores 1600 μJ of energy. When the pd across itdecreases by 2.0 V, the energy stored by it becomes 400 μJ. What is the capacitance of this capacitor?

A 100 μF
B 200 μF
C 400 μF
D 600 μF

But how do you work this out?
4. (Original post by aelahi23)
how so you solve this question

Initially a charged capacitor stores 1600 μJ of energy. When the pd across itdecreases by 2.0 V, the energy stored by it becomes 400 μJ. What is the capacitance of this capacitor?

A 100 μF
B 200 μF
C 400 μF
D 600 μF

But how do you work this out?
E=1/2CV^2

Decreasing the energy by a factor of 4, would mean the voltage would have to decrease by a factor of 2.

Hence the initial voltage across the capacitor should be 4V (2*2).

C=2E/V^2=1600*2/(4^2) = 3200/16 = 200 μF

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5. I assume everybody's finished the ISA now right? How did you guys find them?
6. (Original post by C0balt)
I assume everybody's finished the ISA now right? How did you guys find them?
Pendulum one went well
7. (Original post by C0balt)
I assume everybody's finished the ISA now right? How did you guys find them?
wasnt too bad, did the water flow one. Do you know when the grade boundaries come out for them
8. (Original post by boyyo)
wasnt too bad, did the water flow one. Do you know when the grade boundaries come out for them
One day before the publication of results
9. (Original post by kingaaran)
One day before the publication of results
ohh, but when I did my isa last year, my teacher gave me my mark and grade after he'd marked it thoe
10. (Original post by boyyo)
ohh, but when I did my isa last year, my teacher gave me my mark and grade after he'd marked it thoe
Well ISA/EMPA boundaries don't really change significantly, so using last year's grade boundaries is fairly likely to mirror the boundaries this year. This is because ISA and EMPAs are moderated and standardised units and so the distribution of marks rarely fluctuates significantly.
11. (Original post by C0balt)
I assume everybody's finished the ISA now right? How did you guys find them?
Mine went decent tbh
12. (Original post by Ayaz789)
Mine went decent tbh
I didnt like the oscillation one much
13. (Original post by C0balt)
I didnt like the oscillation one much
I only did the oscillations one😂
14. the water flow one - everyone in my year got bellow 38 ahah - I got 35 oops.. Awaiting the SHM one to come back but I reckon (hope) I've done better in it!
15. (Original post by cowie)
the water flow one - everyone in my year got bellow 38 ahah - I got 35 oops.. Awaiting the SHM one to come back but I reckon (hope) I've done better in it!
Lol everyone got the first question wrong in the water flow one in my class
I had to read the last experiment design question on SHM like 10 times to understand what it was asking XD
16. (Original post by C0balt)
Lol everyone got the first question wrong in the water flow one in my class
I had to read the last experiment design question on SHM like 10 times to understand what it was asking XD
Yeah last question was very difficult compared to other similarly marked questions.. They didn't even give the equation I don't think.
17. (Original post by C0balt)
Lol everyone got the first question wrong in the water flow one in my class
I had to read the last experiment design question on SHM like 10 times to understand what it was asking XD
I got 42 on the SHM one but i got 1/5 for the last one i think because i just wrote whatever came to my mind lol
18. Hello everybody, was wondering, what are some recurring unit 4 multiple choice (or written paper) questions that AQA love to ask most years? Any resources would be appreciated.
19. (Original post by nicos1997)
Hello everybody, was wondering, what are some recurring unit 4 multiple choice (or written paper) questions that AQA love to ask most years? Any resources would be appreciated.
From the top of my head they are quite keen on asking for definitions and stating principles, such as conservation of momentum, gravitational potential, electrical potential etc. Easy marks if you can remember the definition.
20. (Original post by cowie)
Yeah last question was very difficult compared to other similarly marked questions.. They didn't even give the equation I don't think.
equation? Did we need any?
I'm probably gonna find out our mark tomorrow on the SHM one....
(Original post by Ayaz789)
I got 42 on the SHM one but i got 1/5 for the last one i think because i just wrote whatever came to my mind lol
I think I got 42 for the water flow one. I was waffling so much on the last SHM question, I feel bad for the teacher who's marking it

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