Edexcel Physics Unit 4 - 21st June 2011

i think u have to use 3pp 10 million on a mass of on sulphur... that would give something like 0.000009u.... so it rounds up to 0.00001u (what they asked)... LC. is hence 0.0001u

Thank God someone points out that there was an increase in KE

I scrolled through the previous pages and no one mentioned that...

i love u for saying that.... i hope hope hope edexcel reads ur post and magic happens.... lol yes im not making sense .... and i blame the paper for it

Insha Allah.
Good luck, dear. <3

I thought the paper was ok except for that spreadsheet question. Heres what i remember from it:
Mcqs Cant really remember the order
1. Weight
2. loop contracts into a circle
3. time constant = seconds
4. Open the switch
5. 4*10^-4 Wb
6. Particle is moving closer to the speed of light
7. 10MeV/c^2
8. To collide hadrons
(im sure i missed some question :P)

Structured
Proof was easy i got that and the wavelength was 2.something *10^-11
describing the velocity time graph was easy - you just have to say it accelerates firsts and then accelerates in the opposite direction and why ( due to the resultant force acting on the ball because of the electric force it experiences in the field)
The speed of the bat after collision was 0.56m/s (if you used 0.8) or 0.52m/s (if you used 0.77). Even though the difference in the KEs was small - there was still a difference therefore - inelastic (from the students conclusion)
However - am i the only person who noticed that the final KE > initial KE ???? Thats why they asked the about the uncertainty of the student measurement of the height x - the students value was too big because final ke cannot be greater than initial KE - thats impossible because energy is lost during the collision as heat or sound)
Spreadsheet - i managed to prove the first part - couldnt do D5 but i proved E6 using s=ut+.5at^2
Max radius= 2.9*10^-14
Conclusions of Rutherford expt - i think everyone knew this :P
The jelly question with the graph - it was a straight line and you have to find the negative gradient. The constant was 0.00625cm^-1 (or 6.25m^-1) (of course there would be a range for this answer because it depends on your graph)
Particl physics question was simple - for the conservation i guess you can talk about any 3 of 6 things that are conserved : Charge, Mass/Energy, Baryon Number, Lepton Number,Strangeness and Momentum
For the question with sulphur - the change in mass was 0.00233u or something which was much greater than the least count of the trap (0.00001u) therefore it can be measured
Sorry if i missed out something

for question 1 options i thught it was acceleration cuz:
F=mv/t
ma=mv/t
a=mv/mt
a=v/t
Found the paper tougher than previous years....hope edexcel lowers grade boundaries...probably lost abt 14-17 marks...there goes my A

I think everyone who finds a paper hard jumps on to student room to find out how bad they have done :P
I nearly guessed the Grade boundaries for unit 4 in january right. Hopefully these are right aswell

A*62
A 55
B 49
C 42

I thought the paper was ok except for that spreadsheet question. Heres what i remember from it:
Mcqs Cant really remember the order
1. Weight
2. loop contracts into a circle
3. time constant = seconds
4. Open the switch
5. 4*10^-4 Wb
6. Particle is moving closer to the speed of light
7. 10MeV/c^2
8. To collide hadrons
(im sure i missed some question :P)

what did people do for the capacitor question, plus 20% charge over -20% voltage ????

im pretty sure it said the capacitance uncertainty was +/-20%. so if you did the uncertainty in the voltage, i think that would be wrong.

surely the teeeeeeny change in KE means they were conserved? it wasnt a perfect exp....

alsoo...

monday to look forward to y'all...

THREAD FOR UNIT 5:

http://www.thestudentroom.co.uk/showthread.php?p=32374244#post32374244

lets doooo it!!

did the question specifically say there was only uncertainty in the capacitance and not the voltage, i can't remember

that's what I put... I think you were supposed to say elastic (obviously not perfectly since this is practically impossible) and then the question right after that was for you to realise what factors did not make it 'perfectly' elastic

the second part tried to catch people who had written elastic before....so when they read the second part, they change their previous answer to inelastic