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Edexcel Phy4 Exam Today

Just done the paper, think it was really easy. They could have easily made it really hard like other papers!
Heres some of my awnsers:

1. Assumption that galaxies are red shifted (Assume galaxies moving away from us)

2. Define Superposition of waves...etc

3. Sketch graphs, Define SHM.

4. Value of X = 1 x 10^-9.5

5. KEmax: 1.37eV

6. Define Longitudinal wave.....Resonance occurs....Causes collapse

7. a) Radius 74.5m b) Force: 0.077..N

c) Weight & Reaction
d) Resultant Force towards centre, Hence acceleration. (F=ma)
e) Reaction force provides Centripetal Force

Cant remember the others......

Hope this helps others.

-Bengal

Reply 21

kenobi124

1

Bengaltiger

Just done the paper, think it was really easy. They could have easily made it really hard like other papers!
Heres some of my awnsers:

1. Assumption that galaxies are red shifted (Assume galaxies moving away from us)

2. Define Superposition of waves...etc

3. Sketch graphs, Define SHM.

4. Value of X = 1 x 10^-9.5

5. KEmax: 1.37eV

6. Define Longitudinal wave.....Resonance occurs....Causes collapse

7. a) Radius 74.5m b) Force: 0.077..N

c) Weight & Reaction
d) Resultant Force towards centre, Hence acceleration. (F=ma)
e) Reaction force provides Centripetal Force

Cant remember the others......

Hope this helps others.

-Bengal

I don't think the assumption is that all galaxies are red shifted. You can say that a Doppler Effect of light can be observed.... but some galaxies might be moving in our direction...... not always away from us....

Reply 22

Bengaltiger

kenobi124

I don't think the assumption is that all galaxies are red shifted. You can say that a Doppler Effect of light can be observed.... but some galaxies might be moving in our direction...... not always away from us....

Although some galaxies move towards us, you have to ASSUME they travel away from earth.

I could be wrong.

Reply 23

lookenneth

1

Well it seems that my calculations answer is kind of right... because the values were similar to you guys... for the force I put gravitational force and normal reaction force, hope it's correct... I don't think its an actual force though... and my X is 10^-10m and my assumption is that the recession velotity of the galaxies is not constant. Can't write that H is approx here can we? Well that's all the tricky parts I can remember... Hope all comes out well in March...

Reply 24

N9ne

7

That was the easiest Physics paper I've ever done.

Reply 25

kenobi124

1

lookenneth

Well it seems that my calculations answer is kind of right... because the values were similar to you guys... for the force I put gravitational force and normal reaction force, hope it's correct... I don't think its an actual force though... and my X is 10^-10m and my assumption is that the recession velotity of the galaxies is not constant. Can't write that H is approx here can we? Well that's all the tricky parts I can remember... Hope all comes out well in March...

Can I ask everyone, what's the definition of 'Normal Reaction force'?
I asked my dad and he said it is impossible to have a normal reaction force when it's suspended in mid air like that unless if it has a huge ass fan that creates a huge upthrust of air. I don't know if he is correct, but can someone define what normal reaction force is?

Reply 26

Bengaltiger

Newtons law of motion:

"For every action, there is an equal and opposite reaction"

Question stated there was a man in one of the carriages. The reaction comes from the floor of the carriage.

Reply 27

lookenneth

1

right you are...

--------------

right you are... it's unit 1 stuff...

Reply 28

kenobi124

1

Bengaltiger

Newtons law of motion:

"For every action, there is an equal and opposite reaction"

Question stated there was a man in one of the carriages. The reaction comes from the floor of the carriage.

Wasn't the question referring to the carriage?

Reply 29

Yellowmellow

7

kenobi124

Wasn't the question referring to the carriage?

the diagram was the body-force diagram (is that the right term :confused:

) for the man, so the arrow pointing upwards was the contact force exerted by the man on the capsule.

pretty cool paper really, though now i'm wondering if they board will 'revise' the markscheme to make it really specific so that the grade boundaries are kept down. :eek:

Reply 30

snmichaels

1

For the assumption, I stated that all all galaxies emit light of the same frequency. This affects the distance of galaxies and hence, Hubble's constant.

Very easy paper I thought. The only mess ups I can remember doing was that I drew a positive cos graph for velocity instead of a negative. And for definition of plane polarised, I forgot to mentiong, perpendicular to the propagation.

I was a little dissapointed to not find any good meaty 4-5 mark calculation questions. They usually give at least on tricky calculation question. Most of this paper was just explaining things which can get a little dodgy under exam conditions. Oh well, good paper on the whole.

What worries me is that EVERYONE found it really easy and then the grade boundries are going to be high. 100% is an A, 95% is a B, 90% is C, 60% is D and so on... :biggrin:

. Hope not though :smile:

.

Reply 31

Justintabib

11

Phy4 was much easier than what I expected.Normally,whenever i worked through past unit4 papers,i only hoped I'd get lucky in my exam & i was! the paper was relatively easy & straightforward.Didnt expect a topic like expanding universe (v=Hd) to show up for three consecutive sessions (jan-june 05 & jan 06 this time!).About the assumption in estimating age of the Universe,i said universe is expanding & Hubble's law holds true (coudn't think of anything else).
unit5 wasnt that good!i got confused almost in every question even with that capacitor calculation & gravitational attraction questions.the critical question was the one involving the charge thing(the sign of the charge was not even stated),in the last part I wrote charge would accelerate in the direction of the electric force because decreasing d would cause E to increase (E=V/d) so the charge would experience a lager electric force hence there will be a resultant force on the particle (E>F).The unit5 paper was,overall, unexplainable to some extent.Dont know if I've done good or bad.I guess it would all get down to how other students have performed.The practical test was awesome so guess an 'A' would come anyway!
Unit6 paper was strange to say the least.There wasnt any question about accelerators or detectors,& only about 5-10 marks came for analogy between capacitors & decay.All the questions were based on knowledge from previous units so a lot of people found it to be quite accessible (especially holds true for people like me who gave AS+A2 together).the comprehension part was also not as daunting as the previous papers (thanks god!).However,many including me couldn't finish all parts of the paper in time & i couldn't show some already stated relationships.expecting 60-70 outta 80,guess that would do the job to get above 96 (80%) outta 120.
One word of caution for june examinees,be well prepared because I get a feeling june paper's not gonna be as easy as this time!

Edexcel Phy4 Exam Today

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