HSC Physics Question Thread

[12carpim]

@jamonwindyer the answer they had was 3:2 but the equation has to be sqaured on the denominator and numerator but even then I still dont get an answer.

[jamonwindeyer]

Woops! Yeah okay, hmm... Actually, now that I read it again, maybe it means the ratio of those TO EACH OTHER? So, reflected intensity percentage divided by transmitted intensity percentage? Which, interestingly, my answer matches - Yours probably doesn't? I'm stumped, maybe the textbook makes my mistake?

[Adammurad]

Hey, would anyone be able to link us to any good summary cheats on quantum mechanics couldn't find any good ones? Thanks

[bsdfjnlkasn]

Hey there!

I was just wondering what the best way to prepare for the HSC Physics exam was? Which schools have the 'best' papers and until which year of the HSC should we go back to?

Should we be doing anything extra? Apart from learning and possibly rewriting summaries?

Any advice would be super appreciated!!

[jamonwindeyer]

Hey there!

I was just wondering what the best way to prepare for the HSC Physics exam was? Which schools have the 'best' papers and until which year of the HSC should we go back to?

Should we be doing anything extra? Apart from learning and possibly rewriting summaries?

Any advice would be super appreciated!!

There isn't a 'perfect' method to preparing for any HSC Exam, you really just need to do what works best for you - Hopefully your Trials revealed a bit about what works well for you, and what doesn't work quite as well. Build on the strengths and get rid of the weaknesses because only you know how you best learn

That said, obviously practice makes perfect, and you've got about 7 Physics papers from the current syllabus now (2010 and beyond). Try and do as many of those as you can (and really, that might be all the practice exams you need, add a few from THSC if you want more). Supplement that with anything you like - Brainstorms around the big syllabus dot points, teaching your friends the content and having them teach you, anything you think will be helpful for you

[katnisschung]

for the davisson and germer experiment (quanta to quarks focus area 2)
why did annealing of the nickel lead to diffraction? in other words
why didn't diffraction of the electrons occur in their results before the nickel annealed?
i assume it has something due to the nickel forming larger, single atoms??
thanks 

[bsdfjnlkasn]

Hey there!

Could I please get some help with the following questions? Can't seem to find the answer online anywhere.. thank you in advance!

[A TART]

Hey there!

Could I please get some help with the following questions? Can't seem to find the answer online anywhere.. thank you in advance!


(Image removed from quote.)

Types of transmuations:

Alpha Decay: 2 Neutrons and 2 Protons (Nucleus of an Helium atom, often denoted by He)
Beta Decay: 1 electron (or if Beta positve, a Positron)
Gama Deacay: A photon (light) is emitted from an unstable element (often denoted by *)
Neutron Capture: A neutron is added

(I'm not too sure about the HSC course, but I think you need to remember them)

So for the first one, a neutron is added to the reactant, hence it's neutron capture

For the second one, one reactant has resulted in 2 products, one of which is [He] (2 protons and 2 neutrons making a mass number of 4 and atomic number of 2). Hence it is alpha decay.

For the last one it's also neutron capture since a neutron has been added. It might be something else but I'm not sure. (Part of fission? Idk)

b) Since you don't find indivdual neutrons in nature it can be assumed that it's not the first or last one, hence, through elmination, it can be said the second one is a natural process. (which is true since Uranium is unstable and will decay)

c) I would say the last transmutation since it's a part of fission (when a heavier element is split into smaller ones and releases energy). This is how Nuclear power plants work.

[A TART]

I'm so sorry for double posting, but editing ain't working for me for some reason:

for the davisson and germer experiment (quanta to quarks focus area 2)
why did annealing of the nickel lead to diffraction? in other words
why didn't diffraction of the electrons occur in their results before the nickel annealed?
i assume it has something due to the nickel forming larger, single atoms??
thanks 

This is coming from a chemical POV. The size of an atom doesn't change when you treat it, however, the size of a crystal (a bunch of atoms) does. When you anneal a metal, the crystals become larger and often, more uniform. (due to the slow cooling process where atoms have the time to join to form larger crystals as opposed to quenching-where the metal is rapidly cooled and forms small crystals).

A more uniforum arrangement of atoms will leave less gaps for electrons to go straight through, hence, lead to more defraction.

The nickel prior to heat treatment might've been (polyatomic/amorphous, just messy in general). When it was treated, it resulted in a crystalline strucutre: (see pic)
https://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Crystalline_polycrystalline_amorphous.svg/150px-Crystalline_polycrystalline_amorphous.svg.png

I don't think you'll need the chem vocab since this is physics afterall (which is superior to chem).

[jakesilove]

I don't think you'll need the chem vocab since this is physics afterall (which is superior to chem).

So true

[12carpim]

Hey,
I'm not sure if it is necessary to understand but why do some protons not align with a magnetic field in the MRI topic of medical physics.

[austv99]

Hey,
Could i get help this question? I dont understand why it's B.

[pikachu975]

Hey,
Could i get help this question? I dont understand why it's B.

Emf is the negative of the rate of change of flux. This means if you imagine the flux graph, the stationary points on the flux graph will be the x-intercepts of the emf graph (basic 2 unit maths). The maximum flux passing through the coil is at Q and S so there's x intercepts here so it's B or C.

There is maximum emf when the torque is maximum, i.e. coil parallel to magnetic field (theta = 0 in T = nBILcostheta) which is at point P etc, so it must be B then since at P the emf is maximum.

[jamonwindeyer]

Hey,
I'm not sure if it is necessary to understand but why do some protons not align with a magnetic field in the MRI topic of medical physics.

Pretty sure that's beyond the syllabus - And I'd probably butcher the Physics if I tried to explain it it's fairly complicated as far as I know!

[itssona]

hiii pls help :/
a 60pkg drag car completes the 400m with a final speed of 200kmhr. whats the net force on the car assuming the acceleration of the car is constant

my teacher used the fact that v+u/2 =average velocity