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Edexcel Unit 4: Physics on the Move 6PH04 (11th June 2015)

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How did everyone work out the tension question?

Resolved both sides so equated weight with the vertical component and the electrostatic force with the horizontal then divided them to find tan theta.

Reply 501

Destrian

Original post by BP_Tranquility

For the capacitor q, I said that since W=½QV , if the charge halves then the energy stored is divided by 4. So the energy must halve before the charge halves . is that correct?

Posted from TSR Mobile

Yes, thats the same way I did it.

I then wrote out W = 1/2 * V(0)e^(-t/RC) * Q(0)e^(-t/RC)
So: W ∝ (e^(-t/RC))^2, so it decreases faster.

Reply 502

blueynuey1

Please vote on Poll:
http://strawpoll.me/4601250

Reply 503

thatNoseyParker

Original post by iceangel8

Ah k awesome :smile:

At first I used ln0.8 and got a time less than the time constant and I was so confused phew I changed it!

Yeah when I got a time less than the time constant I thought erm what... decided to go back to it at the end. Completely forgot to change it -.- Still, only 2 marks lost, right? As I put the formula down so that's 1 for me

Reply 504

BP_Tranquility

Original post by cerlohee

Hey everyone :smile:

Couldn't find a thread for this anywhere, so decided to make one!
Who else is sitting this exam?

Here's the unit 5 thread!:
http://www.thestudentroom.co.uk/showthread.php?t=3162657&p=53868421

Hey there- I don't suppose you could add a poll to this thread to see what people thought of the exam? :smile:

Reply 505

merong

So annoyed at myself. Made ridiculously stupid mistakes

Reply 506

aero-1997

Anyone want to guess predictions for grade boundaries, to be honest I found it relatively easy maybe.

66-A* 59-A 54-B 49-C

Reply 507

blueynuey1

GUYS THERE IS MASSIVE DOUCHE WHO KEEPS DELETING DOC

HERE IS WORK DONE SO FAR:

unidentified questions :s-smilie:

tuff from MC Questions:

•

Force was F/2 of initial value. +2

•

The conclusion you can’t make from Alpha Particle Experiment = That Nucleus contains Protons and Neutrons. +2

•

High energies required to make particles with large mass

Which question was the one about the difference between a uniform electric field and an electric field due to a point charge?you had to draw a diagram of the electric field between 2 parallel plates and of a point charge. and then compare the electric field strength of them. I.e. Point Charge: E (proportional) 1/r^2. And E = constant for the parallel plates.Diagram: http://www.revisionworld.com/sites/revisionworld.com/files/imce/parallel-plates.gif---------------Question 1. Number of neutrons in a Uranium atom (Z = 92, A= 238) +1
Question 2.
Question 3. If a pennis travels at 5 ms what is its momentumQuestion 4. Question 5. Question 6. Question 7.mv2=p2/mQuestion 8. Question 9. Question 10. Question 11. a. Draw the direction of current in the copper rod. Down. +7 b. State the direction of magnetic field that will cause the rod to move to the right.Into the page. +5
Question 12. Particle physics - identify pion minus quark composition

anti up, strange? Pion minus have no strange quarks (http://en.wikipedia.org/wiki/Pion)+1 Down anti-up +4

140MeV/c2 → 2.49 * 10^(-28) +8

Question 13. This was about the boy in the merry-go-round thing. Find the minimum time taken for the boy to complete one revolution given that the boy's mass is 20 kg and the size of the frictional force is 0.35*(weight of the boy). The second part was: Explain how the time changes if a child of greater mass sits on the merry-go-round.

time = 3.08s +10

independent to mass +7

b explanation -> F = μmg = mrω² therefore μg = rω² so ω independent of mass so T independent of mass

Question 14. This was the 6 marks question about the probe in space. Discuss whether conservation of momentum and energy applies and why its speed increased.Space probe momentum question*Answer from previous MS - http://puu.sh/ikFJk/a2e6029c79.png ↴

+1 TE = KE + PE. When KE increases, PE decreases. Idk. TE constant. Chemical energy transferred to heat and light?Question 15. θ = 41 +3 T = 0.895632 N, T=0.035? +4 Tension = √[mg^2 + F^2]. Where mg = weight of one of the balls. And F = the electrostatic force between the balls (from coulombs law).Then θ = tan-1(o/a) = tan-1(mg/F) = 41°.

Question 16. A question about capacitors. A circuit diagram of a battery and capacitor connected in series was given. The capacitance was 220 nF and the charge on each plate was 3.3 uC, with one having a plus sign and the other a minus sign. a) Calculate the voltage of the battery and the energy stored by the capacitor.b) Calculate the time taken for the capacitor to discharge 80% of its charge.c) Use and equation to determine whether the time taken for the energy stored in the capacitor is greater than or less than the time taken for the charge on the capacitor to halfd) State two advantages of using a data logger to measure the voltage on the capacitor instead of a voltmeter and a stopwatch.a) V= Q/C = (3.3 x10-6)/(220 x10^-9) = 15v energy=2.475*10^-4 J +4R = 20MΩ?
b) Find the time for capacitor to discharge to 0.2 (0.8 through the capacitor) RC = τ = 20*106 * 220*109 = 4.4s Q0/Q= 5 (is it not 0.7). Sorry, put Q and Q0 the wrong way around. It’s correct now.Therefore t = 4.4 ln(5) ≡ -4.4 ln(0.2) = 7.08 s. +2
d)

•

Reduced/ gets rid of human error in measuring time

•

Means that many measurements can be taken - as voltage changes very quickly for a discharging capacitor.

+1

c) Because

and C is constantHence E = kQ2for E become 1/2 EQ need to become 1/√2 Q 1/√2 ≈ 0.7 (≈0.689)Q reaches 0.7Q0 before reaching 0.5Q0Q reaches 0.7Q0 = Energy reaches halfTEnergy reaches half < TCharge reaches half //Let’s use this as the answer since the English language is confusing?
So the time is less for the energy to decrease by half+2
Question 17. Part 1: State what is meant by Faraday's law.

•

Emf induced is directly proportional to the rate of change of flux linkage in a system

•

= ᐃΦ/ᐃtI., so EMF is directly proportional to the change in flux linkage and indirectly proportional to change in time.

Part 2: A diagram of a magnet hung vertically (with N at the bottom and S at the top) on a spring with it placed inside a copper ring was given. The question was: The magnet is displaced and then let go. It oscillates. Why does this produce an alternating current in the ring?

•

Change in B field

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alternates as magnet oscillates up and down

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Rate of change of flux greatest when speed of magnet greatest

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meaning a maximum current

Part 3: The given value was 0.035 Ts^-1 Which is (n(BA))/Time Therefore A = GIVEN RADIUS^2*PI So EMF = 0.035*pi*radius^2EMF = I(r +R) but as there is no internal resistance, r=0 so EMF = IRTherefore divive the emf/given resistance Gives Currrent = 4.01A +6 I = 4.10 A ?

Question 18. Show that B = 2fme.From formula sheet:r = mV/BQ and v = ωr and ω = 2π/T = 2πf
B = mV/Qr = mω/e = m2πf/el
Question 19.Question: Describe and explain the events shown in Photograph?-Charged particle collision with proton created two particles, one charged and one neutral-Charged particle goes along path of X-Neutral particle travels from X to Y-Neutral particle leaves no track as no charge (only charged particles show in bubble chamber)-Neutral decays into matter/anti matter pair at Y as tracks are equal (radius of curvature) but in opposite directions (momentum conserved) so mass is same for both but opposite charges

Reply 508

PBatch

Original post by aero-1997

Anyone want to guess predictions for grade boundaries, to be honest I found it relatively easy maybe.

66-A* 59-A 54-B 49-C

It was very, very similar to Jan. 2015 IAL so I think these boundaries are spot on.

Reply 509

cerlohee

Original post by BP_Tranquility

Hey there- I don't suppose you could add a poll to this thread to see what people thought of the exam? :smile:

will do now

Reply 510

Izzy1997

Original post by MangleKuo

Let's make an unofficial mark scheme all together by editing this google document!!

+ Write down the question if you can remember it
+ If you see an answer you agree , add [+1] behind it
+ If you have a different answer, write it below the old one
+ If you can't remember the number of the question, put it in the "unclassified question"

Think I've been blocked for saying stop?

Reply 511

blueynuey1

Please vote on Poll:
http://strawpoll.me/4601250

Reply 512

cerlohee

Original post by BP_Tranquility

Hey there- I don't suppose you could add a poll to this thread to see what people thought of the exam? :smile:

It won't let me! Will post on the moderator thread wherever that is

i failed

Original post by justthatprick

Only? pshhht I probably got around 77 AND I was being hard on myself

Joke's on you.

I have an unconditional offer to Sussex and I need 3A's to get a £3000 financial reward.

Getting an A* in physics doesn't directly give me anything (no uni place or money), aside from a little *

Reply 515

Dancatpro

Original post by Freddy-Francis

i failed

That's a shame mate, by "failed" do you mean you don't think you got the grade you were hoping for?

Reply 516

LukeBarnett

Original post by iceangel8

Resolved both sides so equated weight with the vertical component and the electrostatic force with the horizontal then divided them to find tan theta.

Ended up with a angle of 41 degrees I think and a Tension below 1, anyone else get this?

Reply 517

MARKMARKMARKMARK

Was it just me or was that pretty easy?

Posted from TSR Mobile

Reply 518

daniel666545

hello, your answers seem right, however, question 14 is a bit different. The probe ejects empty fuel tanks by a explosion. therefore, there is energy lost to heat ( from the explosion ) and energy is not conserved.

Reply 519

Freddy-Francis

Original post by LukeBarnett

Ended up with a angle of 41 degrees I think and a Tension below 1, anyone else get this?

ya thats right.

I messed up on the easy one xD
hopin for the ecf marks.
I worked out E=kQ/r^2 and used E instead of F and did everything else correct

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Edexcel Unit 4: Physics on the Move 6PH04 (11th June 2015)

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