9702_w15_qp_22 Preparations.

[The Sarcastic Retard]

ahmedish
About 9702_w10_qp_23 Q2:
Crystalline solid: Solid containing ions in a regular lattice structure. It is a long range structure because the lattice consists of repeating units of ions in a regular arrangement.
Polymer: Long chains of monomers (repeating units). They can have cross-linking structures or tangled bits. Cross-linking polymers tend to be stronger because van der Waals forces are definite there, whereas tangled polymers are just like of spaghetti - completely random.
Amorphous: Has no fixed arrangement of particles.

Hope this helps.

P.S: I'd like it if someone elaborated on the amorphous part.

A solid, that lacks the long-range order characteristic of a crystal.

 

[DarkEclipse]

ahmedish
Interference: the formation of points of cancellation and reinforcement when 2 coherent waves pass each other.

 

[paperneeder100]

Thanks everyone! You not only helped ahmedish, but me too.

 

[ahmedish]

So crystalline: long range order due to arrangement of *particles* in a lattice, so it's repeated
amorphous: short range order, irregular arrangement
polymers: long chains of repeated monomers/ molecules, with cross-linking between chains.
that all correct? thanks all btw!

 

[ahmedish]

Oh, last thing, do all my answers have to be according to the least number of s.f of the values used? I always used 3s.f and didn't give it much thought

 

[DarkEclipse]

Oh, last thing, do all my answers have to be according to the least number of s.f of the values used? I always used 3s.f and didn't give it much thought

3 s.f. is fine.

 

[paperneeder100]

3 s.f. is the norm, unless explicitly stated by the question, which is quite rare.

 

[paperneeder100]

polymers: long chains of repeated monomers/ molecules, with cross-linking between chains.

Polymers aren't necessarily supposed to be cross-linking. The can be tangled chains too. Thermoplastics are one such example of polymers which have tangled chains.

 

[The Sarcastic Retard]

I have attached ms too in the same pic.
I have doubt in last two question where I kept question mark.
How KE and how energy can be calculated?

Physicist
paperneeder100
DarkEclipse
ahmedish

Also, how to draw graphs of particular time asked in question?
Example : https://ede1498389cf63c6355cde6280cbfca2e8f14503.googledrive.com/host/0B1ZiqBksUHNYcm4zOGppaW5nZXc/June 2013 (v2) QP - Paper 2 CIE Physics.pdf Q5(b)(iii)


Thanks.

 

[qwertypoiu]

I have attached ms too in the same pic.
I have doubt in last two question where I kept question mark.
How KE and how energy can be calculated?

Physicist
paperneeder100
DarkEclipse
ahmedish

Also, how to draw graphs of particular time asked in question?
Example : https://ede1498389cf63c6355cde6280cbfca2e8f14503.googledrive.com/host/0B1ZiqBksUHNYcm4zOGppaW5nZXc/June 2013 (v2) QP - Paper 2 CIE Physics.pdf Q5(b)(iii)


Thanks.

When the alpha particle is emitted it moves so it has kinetic energy.

The energy is already given.
5.3MeV

Remember eV is 1.6x10^-19J
M means mega, or 10^6
So 5.3MeV = 5.3*1.6*10^-19*10^6
Power is just dividing the above by time.

 

[qwertypoiu]

I have attached ms too in the same pic.
I have doubt in last two question where I kept question mark.
How KE and how energy can be calculated?

Physicist
paperneeder100
DarkEclipse
ahmedish

Also, how to draw graphs of particular time asked in question?
Example : https://ede1498389cf63c6355cde6280cbfca2e8f14503.googledrive.com/host/0B1ZiqBksUHNYcm4zOGppaW5nZXc/June 2013 (v2) QP - Paper 2 CIE Physics.pdf Q5(b)(iii)


Thanks.

Oh and the wave part.

Number of waves/oscillations = frequency * time = 50Hz * 5ms = 0.25

So since one complete cycle would be going down and coming back up, ½ is just going down, and ¼ is going till centre.
So it'll be a straight line through the centre

 

[The Sarcastic Retard]

Oh and the wave part.

Number of waves/oscillations = frequency * time = 50Hz * 5ms = 0.25

So since one complete cycle would be going down and coming back up, ½ is just going down, and ¼ is going till centre.
So it'll be a straight line through the centre

Thanks a lot.
Can u show me on the graph of question paper please? Thanks.

 

[The Sarcastic Retard]

http://papers.gceguide.com/A Levels/Physics (9702)/9702_s11_qp_22.pdf
Q6(ii)

 

[ahmedish]

3 s.f. is fine.

3 s.f. is the norm, unless explicitly stated by the question, which is quite rare.

Thats what I thought as well, but in the marking scheme they're usually written to two or three s.f. depending on the number of s.f in the question

 

[ahmedish]

http://papers.gceguide.com/A Levels/Physics (9702)/9702_s11_qp_22.pdf
Q6(ii)

A bright fringe forms when phase difference is 0 or 360 degrees(we write 360 because you can say n360, where n can be equal to 0,1,2,3), when they're crest on crest, *constructive interference* so the amplitude doubles
A dark fringe forms when phase difference is 180 degrees, they meet crest on trough, cancelling out.

Thanks a lot.
Can u show me on the graph of question paper please? Thanks.

Its just a straight line along the dashed line...
because T= 1/50= 0.02 and 5x10^-3 is 1/4 of that, so they move 1/4 of a cycle, the crest moves 1/4 wavelength to right, trough 1/4 wave length to left, so they're gonna cancel out since they each moved to opposite directions, they combine destructively, giving 0 amplitude.
if it was after T=10ms, the wave wouldve formed but in opposite direction. (crest becomes trough, trough becomes crest)

 

[qwertypoiu]

Thanks a lot.
Can u show me on the graph of question paper please? Thanks.

 

[ahmedish]

Can anyone explain 4c and the one after??? http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_w07_qp_2.pdf

 

[The Sarcastic Retard]

Can anyone explain 4c and the one after??? http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_2.pdf

Find out the minimum area and subtract is from the cross sectional area.

 

[The Sarcastic Retard]

I suck at this graphs, even kineamatics.
Any tips like this??

 

[ahmedish]

I

Find out the minimum area and subtract is from the cross sectional area.

I dont get the whole minimum area thing.. I got 2, we are supposed to subtract that from 3.2, but i dont get why