[number23]

(Original post by callmenighthawk)
can someone PLEASE help me with the derivation.

my teacher said we won't need to know how to derive it fully, just understand why it is derived like that (what laws and principles are happening) as it's never come up as fully deriving it.

im not sure about deriving it, but i think we need to know about the assumptions and about collisions and force and time with the walls of the container

[schizopear]

(Original post by kimmey)
hi does anyone have the mark scheme to the exam style questions right at the end of the book. i have chapters 9-12 but i dont have the ones right at the end. if anyone could post a link to them i would be eternally grateful

here

[number23]

quite a good idea for gases/thermal physics:

[Onee-chan]

(Original post by callmenighthawk)
can someone PLEASE help me with the derivation.

my teacher said we won't need to know how to derive it fully, just understand why it is derived like that (what laws and principles are happening) as it's never come up as fully deriving it.

I'm fairly sure that you do need to be able to derive it fully. Although they won't ask you to do so, as it will be too time-consuming, they could potentially ask you to derive any part of it.

What don't you understand about the derivation? It's probably better to give you a tailored response rather than regurgitating the textbook.

[callmenighthawk]

(Original post by Onee-chan)
I'm fairly sure that you do need to be able to derive it fully. Although they won't ask you to do so, as it will be too time-consuming, they could potentially ask you to derive any part of it.

What don't you understand about the derivation? It's probably better to give you a tailored response rather than regurgitating the textbook.

I'm poor at derivation, if you could go through all of it (practice for you too ) then that would be great.

If not then I'll get back to you soon on what parts I don't understand

thanks man

[kimmey]

(Original post by schizopear)
here

thanks pal

[Harney94]

anyone know where i can get all of the past papers for PHYA5 AQA, or any sites with relevant questions for the exam. I cant seem to find a site to access all of the papers

[number23]

Do we need to know an experiment in detail to work out radius of the nucleus?

Also, is this derivation good enough for kinetic theory? :

• consider box of molecules
• change in momentum=2mv
• time between collisions=(2l)/v
• F=(mv^2)/l
• P=(mv^2)/V
• considering N molecules: P=(Nm(average speed)^2)/V
• Considering three dimensions: P=(1/3)(Nm(average speed)^2)/V

Leading to

[Glacier]

Are we supposed to use 1 u = 931.3 MeV or 931.5 MeV? The textbook says 931.3, but the furmulae booklet says 931.5 MeV.

[lee_vassallo]

(Original post by Glacier)
Are we supposed to use 1 u = 931.3 MeV or 931.5 MeV? The textbook says 931.3, but the furmulae booklet says 931.5 MeV.

931.3 - I have never come across 931.5 in any mark schemes and its says 931.3 in the formulae booklet

[jonnny]

Are the astrophysics papers found here (June 2006, 2007 and 2008) relevant to the astrophysics exam this year on the 18th? thanks

[Glacier]

(Original post by lee_vassallo)
931.3 - I have never come across 931.5 in any mark schemes and its says 931.3 in the formulae booklet

According to http://store.aqa.org.uk/qual/gce/pdf...5-W-A2-DFB.PDF, "1u is equivalent to 931.5 MeV", under "atomic mass unit" on the first page.

[--NWzD9--]

Which of these lines, blue or red, would be an acceptable path for the evolution of the Sun through its lifetime on the HR diagram? (Im assuming one of them is correct, please could you tell me if there not)

[kimmey]

can someone doing medical physics explain what and how an intensifying screen works for me

[internet tough guy]

unit 4 or unit 5, which is more difficult do you all think?

[jonnny]

(Original post by internet tough guy)
unit 4 or unit 5, which is more difficult do you all think?

Gotta be unit 5


This was posted from The Student Room's iPhone/iPad App

[Onee-chan]

(Original post by callmenighthawk)
I'm poor at derivation, if you could go through all of it (practice for you too ) then that would be great.

If not then I'll get back to you soon on what parts I don't understand

thanks man

(Original post by number23)
Do we need to know an experiment in detail to work out radius of the nucleus?

Also, is this derivation good enough for kinetic theory? :

• consider box of molecules
• change in momentum=2mv
• time between collisions=(2l)/v
• F=(mv^2)/l
• P=(mv^2)/V
• considering N molecules: P=(Nm(average speed)^2)/V
• Considering three dimensions: P=(1/3)(Nm(average speed)^2)/V

Leading to

To Callme: Looks like there's your prove .

To number: I think we need to know the 3 experiments: alpha scattering then use probability to estimate the ratio of nuclear to atomic diameter, calculating the least distance of separation and high energy electron diffraction.

[callmenighthawk]

(Original post by Onee-chan)
To Callme: Looks like there's your prove .

To number: I think we need to know the 3 experiments: alpha scattering then use probability to estimate the ratio of nuclear to atomic diameter, calculating the least distance of separation and high energy electron diffraction.

I can do it now, thank you anyway

[callmenighthawk]

(Original post by Onee-chan)
To Callme: Looks like there's your prove .

To number: I think we need to know the 3 experiments: alpha scattering then use probability to estimate the ratio of nuclear to atomic diameter, calculating the least distance of separation and high energy electron diffraction.

how

[kimmey]

(Original post by callmenighthawk)
how

well as the alpha particle approaches the atom kinetic energy gets converted to electric potential energy.

so i think...

0.5mv^2=Qq/4piepsilon0R

where R is the least distance of separation