You are Here: Home >< Physics

# AQA Physics Unit 4 Thread - JAN 28th 2010 (Post Exam) watch

Yeah whoever drew that graph is an idiot,, did your teacher tell you to draw waves??? its just a |Sine| curve! :P

the momentum of water was answer b 5.6*10^-2 use volume and Area to calculate velocity and density and volume to do mass!
I would be this so-called 'idiot'. Why would it be a |sine| curve? The rate of change of Kinetic energy is increasing.
2. yeah, the second thing should have been resistance in wires (^^)
3. Thick Copper Wires :d
4. ohh and it is a sine curve cos the Energy is gained in a curvy way when the potential energy drops! it just sort of is.. its circuar motion stuff
5. would eddy currents and the core having to be remagnetised due to ac be accepted as 2 different points for the 6 marker?
6. (Original post by kayn)
I don't think he is - If the data in the question is to 2 sf then your final answer also should be (although it dosn't really matter unless they ask you for a correct no. of sf)

7. My KE Graph
8. Thought the exam was alright. Found the multiple choice questions pretty straight forward and the written paper was quite easy too. Perhaps I ****** up quite badly in that case.
9. i like that image.. i like it alot
10. (Original post by mazchaz)

My KE Graph
How many marks was that?
Nice decoration
11. What the hell was up with this exam. I don't even know why they make us do multiple choice, I hate it. I'm absolutely terrible at it. As for the written bit, it was like WHAT THE HELL!

It was an okay exam, just really easy to make mistakes. Like about transformers, I blabbed that. Also about the satellite question, I was like "how the hell do you get the acceleration?" And I didn't have linear velocity, so I kind of guessed they were geo-synchronous and had a time period of 24H.

Also the last question about power and how much is wasted and the price of this, was total crap. I mean what the hell, figuring out how much something costs is not Physics at all.

Also I couldn't get "show 90%" of the energy is used up by 25s" in the capacitor question, I kept getting 60% and I was like FOR ****S SAKE.

Also for the graph for Kinetic energy of the swinging girl, I put one "boob" like thing =/ maybe i'll get 1 mark for having the right idea.

MUH! This exam was so wishy-washy. Even my resit for Physics Unit 2 was the same. I think AQA need to stop hiring crap exam writers. And i don't like the idea we don't really have past papers to do, apart from look at old questions and some stuff is not even on it (i.e. Transformers). I hate being a guinea pig.
12. (Original post by mazchaz)

My KE Graph

full marks.
13. centripetal acceleration of the satellite 3.30 ms-2 anyone?
What the hell was up with this exam. I don't even know why they make us do multiple choice, I hate it. I'm absolutely terrible at it. As for the written bit, it was like WHAT THE HELL!

It was an okay exam, just really easy to make mistakes. Like about transformers, I blabbed that. Also about the satellite question, I was like "how the hell do you get the acceleration?" And I didn't have linear velocity, so I kind of guessed they were geo-synchronous and had a time period of 24H.

Also the last question about power and how much is wasted and the price of this, was total crap. I mean what the hell, figuring out how much something costs is not Physics at all.

Also I couldn't get "show 90%" of the energy is used up by 25s" in the capacitor question, I kept getting 60% and I was like FOR ****S SAKE.

Also for the graph for Kinetic energy of the swinging girl, I put one "boob" like thing =/ maybe i'll get 1 mark for having the right idea.

MUH! This exam was so wishy-washy. Even my resit for Physics Unit 2 was the same. I think AQA need to stop hiring crap exam writers. And i don't like the idea we don't really have past papers to do, apart from look at old questions and some stuff is not even on it (i.e. Transformers). I hate being a guinea pig.
for the 90% bit, i kept getting 10%
15. Some answers I remember, anyone got similar?

Multiple choice:

- The time period had r^3/GM in it
- An oscillating mass would return to its natural frequency after driving force removed
- 1000uF vs. 100uF capacitor was 10xenergy, 10xcharge stored
- displacement is pi/2 out of phase with velocity?

Paper:

- velocity was 2.21 in Q1
- Transformer increasing voltage to 12V - no effect on time to 90% discharge, quadruple energy stored
- 23.2s time constant
- 6x10^-5 current
- gpe was gp times m, for that 'state the relationship'
- Kinetic energy graph was 0 at 0, max-positive at T/4, 0 at T/2, max-positive at 3T/4 and 0 at T. I ended up with two parabolas but not sure about the shape. Is it like a sin^2(x) curve and if so how were we meant to know that shape?
- I got £4.20 for the cost, was that "about £4" or did anyone get closer? How did those people who got 3.78 get it? I got 3W for the previous part.
- How much were we meant to write for the very first part; describe energy changes in pendulum? I wrote about 3 times as much as the space required, what would the two marks be?
16. I kept getting like 12.5% for the show 90% decrease, so I hope thats about right
17. Ah shet, guess I messed up the graph then.

(Original post by fabregassed)
for the 90% bit, i kept getting 10%
Thats coz you have to minus it from 100% or do it in the formula.
18. (Original post by Game_boy)
Some answers I remember, anyone got similar?

Multiple choice:

- The time period had r^3/GM in it
- An oscillating mass would return to its natural frequency after driving force removed
- 1000uF vs. 100uF capacitor was 10xenergy, 10xcharge stored
- [COLOR="Black"]displacement is pi/2 out of phase with velocity?[/COLOR]Paper:

- velocity was 2.21 in Q1
- Transformer increasing voltage to 12V - no effect on time to 90% discharge, quadruple energy stored
- 23.2s time constant
- 6x10^-5 current
- gpe was gp times m, for that 'state the relationship'
- Kinetic energy graph was 0 at 0, max-positive at T/4, 0 at T/2, max-positive at 3T/4 and 0 at T. I ended up with two parabolas but not sure about the shape. Is it like a sin^2(x) curve and if so how were we meant to know that shape?
- I got £4.20 for the cost, was that "about £4" or did anyone get closer? How did those people who got 3.78 get it? I got 3W for the previous part.
- How much were we meant to write for the very first part; describe energy changes in pendulum? I wrote about 3 times as much as the space required, what would the two marks be?
SAID 3 PI OVER TWO
19. (Original post by 2710)
Ah shet, guess I messed up the graph then.

Thats coz you have to minus it from 100% or do it in the formula.
snap with the graph, I put one curve instead of two =/ Although I think AQA has a thing for efficiency like, had it in last years ISA, twice in this year paper and once in my resit
20. (Original post by SuperMario88)
SAID 3 PI OVER TWO
3 Pi by 4?

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 20, 2011
The home of Results and Clearing

### 2,404

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. Keele University
Sun, 19 Aug '18
2. University of Melbourne
Sun, 19 Aug '18
3. Sheffield Hallam University
Tue, 21 Aug '18
Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE