Help in Physics P4

[Jazib]

oct 07 Q 2 a ii (y didnt he used V=4/3 pi Rcube)
june 06 7 c (what is the relation b/w lemda n separation of rings)
june 06 2 b ii ( how to calculate moles legt in cylinder)
june 08 Q 11 a ii 2 (this thing is not present in booklet)
if any1 alive reply ASAP! ty

 

[PlanetMaster]

Oct/Nov 07 Q.2a(ii):
You don't have radius of a Helium-4 atom! Or do you?

May/June 06 Q.7(c):
λ is the wavelength which is directly proportional to ring diameter (common sense).

May/June 06 Q.2b(ii):
You don't need to calculate moles left in cylinder.
Once you have calculated volume of gas in cylinder at 1.85x10^5Pa,
subtract the volume of gas that remains in cylinder (4x10^4cm³) from it
and divide it by the volume of gas in balloon.

 

[Jazib]

radius of He can b assumed to b separation/2 between the two neuclei! n what is this cube root anyway? this is also assumed...
n i got the others. thnx

 

[nannes]

O/N 04 Q2...i do get the question and know how to solve it..i jus dont get the square and stuff

 

[PlanetMaster]

radius of He can b assumed to b separation/2 between the two neuclei! n what is this cube root anyway? this is also assumed...
n i got the others. thnx

Seperation/2 makes sense but cube root is a better approximate.
Did you try using seperation/2?

 

[Jazib]

i did used this separation/2. then i put substituted value of radius in the formula for volume of sphere (simce v assume dat nucleus is a perfect sphere throughout our course in physics) so this method SHOULD B OK as well.
i dunno y examiner just took a cube root...

 

[PlanetMaster]

I don't see any problems with your method.
And I must say it was a nice catch.

 

[Jazib]

thx a lot about that
soo... mark scheme isnt evrythin right? somthin out of it, if right is ok also?

 

[PlanetMaster]

The method they gave was absolutely right.
You found an alternate to it and doesn't makes marking scheme wrong!

 

[Jazib]

hmmm... thnx for u r help dude!