AQA Physics A - PHYA5 (18/06/12) - Exam thread

do we have to learn about the different radioactive experiments in the book? such as ionisation to deduce the ionising effect of different types of radiation, cloud chamber observations, absorption tests etc?

Reply 182

icedragon

OP

Original post by Voglie

Need to get like a low A or high B on this to get an A in physics and meet my offer. But I've only gone through the nuclear stuff so far, still have Astrophysics to do and can't seem to find any good notes etc on it.

There isn't that much about tbh. If you can get hold of the AQA A Physics book by CGP that has a load of good stuff on astro. And also the pdf's in my first post are okay, they have some questions too.

Reply 183

Original post by Troll the Trolls

sciencemathsmaster.weebly.com/uploads/6/3/2/4/6324568/nuclear_physics_binding_energy.pdf
Can smeone help me with question 4?
I can find the mass of all the constituent nucleons in iron but i dont see how im ment to know the mass of the actual iron nuclus,, its in the mark scheme but doesn't say where they got it from and theres no other info in the question -_-

wheres the mark scheme?

Reply 184

Original post by Dominic93

I'm in the opposite position to you, astro seems ok but nuclear is hard to find stuff on. What have you been using?

I went through the Nelson Thornes AQA Physics Book chapters 9-12. Then just did some questions and 3 Section A past papers (the recent ones). Didn't make any mistakes so think i'm ready for that one. But the Astrophysics, going through the same nelson thornes at the moment, quite a bit to go though and then i'll do the same just do some questions I guess.

Reply 185

Original post by Troll the Trolls

sciencemathsmaster.weebly.com/uploads/6/3/2/4/6324568/nuclear_physics_binding_energy.pdf
Can smeone help me with question 4?
I can find the mass of all the constituent nucleons in iron but i dont see how im ment to know the mass of the actual iron nuclus,, its in the mark scheme but doesn't say where they got it from and theres no other info in the question -_-

4. a) Binding energy is the energy required to break all the bonds holding the nucleons together in a substance, i.e. to reduce a substance to it's constituent nucleons.

b) i) E=mc^2
1u = 931.3MeV
mass of Fe-56 = 55.93494u (looked up on wiki)

(((26x1.00728) + (30x1.00867) - 55.93494) x 931.3)/56 = 8.56MeV per nucleon

ii) mass of Fe-56 = 55.93494u
1u = 1.661x10^-27 kg
(26x1.00728) + (30x1.00867) + (26x(5.5x10^-4)) - 55.93494 = 0.52874u = 8.78x10^-28 kg

(edited 11 years ago)

Reply 186

Chris250

A metal disc X on the end of an axle rotates freely at 240 revolutions per minute. The moment of inertia
of the disc and the axle is 0.044 kg m

a Calculate the angular momentum of the disc and the axle

b After a second disc Y that is initially stationary is engaged by X, both discs rotate at 160 revolutions
per second. Calculate the moment of inertia of Y

c Show that the total loss of kinetic energy is 4.6 J

I got part a and b, but I can't seem to prove C, any ideas?

Reply 187

ASaunders

For the lens diagrams, are we allowed to draw a single line with arrows at both ends, or do we have to draw the actual lens?

Reply 188

number23

15

Original post by Voglie

4. a) Binding energy is the energy required to break all the bonds holding the nucleons together in a substance, i.e. to reduce a substance to it's constituent nucleons.

b) i) E=mc^2
1u = 931.3MeV
mass of Fe-56 = 55.93494u (looked up on wiki)

(((26x1.00728) + (30x1.00867) - 55.93494) x 931.3)/56 = 8.56MeV per nucleon

ii) mass of Fe-56 = 55.93494u
1u = 1.661x10^-27 kg
(26x1.00728) + (30x1.00867) + (26x(5.5x10^-4)) - 55.93494 = 0.52874u = 8.78x10^-28 kg

if binding energy is the energy to reduce a nucleus to constituent nucleons, why is it involved in nuclear fusion, when you're not breaking up a nucleus?

Reply 189

Original post by number23

if binding energy is the energy to reduce a nucleus to constituent nucleons, why is it involved in nuclear fusion, when you're not breaking up a nucleus?

Because mass defect is involved in nuclear fusion, and binding energy=(mass defect) x c^2.

The energy given out is thus the change in binding energy.

Reply 190

Original post by ASaunders

For the lens diagrams, are we allowed to draw a single line with arrows at both ends, or do we have to draw the actual lens?

Pretty certain that a single line (with arrows at the end showing the type of lens) is plausible.

Reply 191

desijut

10

Original post by Crystal_Heart

Heyyy,
Been revising and I'm getting really muddled by special relativity in the Turning Points option. Like picking which one is t or t0 and l or l0. And which frame of reference you're in.
Just wondering if anyone could put it simply, or has any notes, that are less confusing that the textbook! :/
Any help would be reallyyy appreciated. Thanks. :smile:

ok. Let's start with inertial frame of reference. The way i see it is as a point of view where where the objects are stationary or at constant speed (cant be accelerating or it gets more complex)

As for choosing

t

or

t_0

etc Give me some examples and i will try to explain as best i can which i choose for what and why.

Reply 192

fruktas

2

Original post by ASaunders

For the lens diagrams, are we allowed to draw a single line with arrows at both ends, or do we have to draw the actual lens?

I would say the actual lens, but only show refraction once, not twice (entrance and exit)

Reply 193

TheRenaissanceMan

9

If anyone needs help understanding the Mass Defect and Binding Energy

[video="youtube;ndUqBklUYDg"]http://www.youtube.com/watch?v=ndUqBklUYDg[/video]

Reply 194

When is N=N(0)*e^-lambda(t) used and when do u use N=0.5^nN ?

Reply 195

Onee-chan

Original post by Troll the Trolls

sciencemathsmaster.weebly.com/uploads/6/3/2/4/6324568/nuclear_physics_binding_energy.pdf
Can smeone help me with question 4?
I can find the mass of all the constituent nucleons in iron but i dont see how im ment to know the mass of the actual iron nuclus,, its in the mark scheme but doesn't say where they got it from and theres no other info in the question -_-

Just had a look, I have no idea either! :tongue:

Original post by natninja

Quite possibly, there's a legal thing that in each three year period they have to cover everything on the syllabus so whatever wasn't there in the last two years will come in this one I think

Okay so in June 2011 they had an idea gas Q, so probably won't be that. I haven't looked at the June 10 yet...

So it could be radioactivity, binding energy or thermal physics? (Not useful summary at all :tongue:

)

Okay a really horrible radioactivity question I can think of would be "Describe how you can varify the inverse square law of gamma radiation experimentally."

Binding energy: "What happens to fuel rods after they are used?"

Thermal physics: "Describe how to measure the specific heat capacity of ice"

Ideal gas (in case they thought it was necessary): Explain in terms of the kinetic theory, why changing the temperature and/ or volume affects the pressure of the gas.

Reply 196