HSC Physics Question Thread

[winstondarmawan]

Would appreciate help with the following, TIA.
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22368857_1345010415624478_564241496_o.png?oh=30c594a949bd76361f09b328f04f86f6&oe=59DBD1CE
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22345179_1345046995620820_683957314_o.png?oh=3813959ef0fe3f95977c336eef6c3d7d&oe=59DBC189
Quanta:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/22330778_1345047115620808_1229680097_n.png?oh=9812596fc2e4c9286ffd492c6a0eec6b&oe=59DB8039
This is from the sample answers, not sure how Bohr used LCM and LCE for his postulates. Can someone please explain?

[blasonduo]

Would appreciate help with the following, TIA.
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22368857_1345010415624478_564241496_o.png?oh=30c594a949bd76361f09b328f04f86f6&oe=59DBD1CE
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22345179_1345046995620820_683957314_o.png?oh=3813959ef0fe3f95977c336eef6c3d7d&oe=59DBC189
Quanta:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/22330778_1345047115620808_1229680097_n.png?oh=9812596fc2e4c9286ffd492c6a0eec6b&oe=59DB8039
This is from the sample answers, not sure how Bohr used LCM and LCE for his postulates. Can someone please explain?

Hello! I can help you with the first one, but I don't do quanta to quarks

For the first one, the huge hint here is that they are both in geostationary orbits. As tower B is with along the equator, it follows the motion of earth (which geostationary satellites do!) So due to this orbital velocity, when the mass is dropped at tower B, It will not fall but however orbit around Earth.

Tower A is slightly different, It is in a geostationary height, but it is currently experiencing no orbital velocity, so when It drops, It will fall. As we have to explain the motion, we need to include that its velocity will continuously fall faster, However, its gravitational acceleration will not be 9.8 when dropped but as it gets closer to the earth's surface, will approach an acceleration of 9.8.

This is all I can think of, and I'm pretty sure this will give full marks

[bsdfjnlkasn]

Would appreciate help with the following, TIA.
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22368857_1345010415624478_564241496_o.png?oh=30c594a949bd76361f09b328f04f86f6&oe=59DBD1CE
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22345179_1345046995620820_683957314_o.png?oh=3813959ef0fe3f95977c336eef6c3d7d&oe=59DBC189
Quanta:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/22330778_1345047115620808_1229680097_n.png?oh=9812596fc2e4c9286ffd492c6a0eec6b&oe=59DB8039
This is from the sample answers, not sure how Bohr used LCM and LCE for his postulates. Can someone please explain?

Hey there,

I do Q2Q so hopefully can help you out

So Bohr's second postulate is that the energy between the electron's quantised orbits is equal to E = hf. As the energy of the orbits are exact (quantised) they require exact amounts of energy to move from one shell to another. This amount of energy is quantified by E = hf. Bohr was able to account for the hydrogen emission spectra because specific frequencies of light are emitted when electrons move from one shell to another. And all the energy is conserved when it is absorbed from an incoming source and converted into kinetic energy (so velocity and light) hence, LCE.

LCM also comes into it when we consider how incoming energy is completely absorbed by the electron if it is the amount it requires to move between electron shells (all or nothing principle). This interaction is considered an elastic collision in which the energy's (e.g. a photon) momentum is transferred without any losses. This energy then allows it to move to a higher electron shell, but because the mass and velocity were conserved, we satisfy the LCM.

Hopefully that helped

[bsdfjnlkasn]

Hey guys!

Although the rest were incorrect, shouldn't D (which is the answer) say that all of the external magnetic field is excluded? Instead of some?

Thank you! It could be that my understanding still needs to be refined...

[blasonduo]

Hey guys!

Although the rest were incorrect, shouldn't D (which is the answer) say that all of the external magnetic field is excluded? Instead of some?

Thank you! It could be that my understanding still needs to be refined...

Hey! It's a good thing the rest were clearly wrong, as I probably would've gotten this wrong!

I'm pretty sure it says some, as not all magnetic field lines could be influenced (see picture)

So assuming the magnet makes a large enough area, some of the further out magnetic field lines might not be influenced?

As I said before, If this question had an answer that said "all" then the question becomes silly. I'm pretty sure they were just testing for the "exclusion" part

[austv99]

Hey, would appreciate help with this question
TIA

[blasonduo]

Hey, would appreciate help with this question
TIA

Hey, I LOVED this question!

Now to start with this question, look where the wires are going, they act as electromagnets as well as being the actual coil for the motor!

From the diagram alone, we can work out the poles of the electromagnets by following the direction of the current. With the one on the right, we work out using North (anti-clockwise) or South (clockwise) and we can clearly see that the closer side is a SOUTH pole.

Using the same method, we can figure out the pole on the left magnet, and it will show that the closer side is NORTH. So the magnetic field is going left to right. Using the right-hand palm rule, we can figure out that the motor will move clockwise So A and C are wrong.

Here comes the fun part!

Now this is AC, so the current will swap direction, so take the diagram and swap the + with a - and vice versa, and DO THE EXACT SAME THING. You will notice that the poles have swapped! Where the magnetic field is now going RIGHT to LEFT. Follow the current and use the right-hand palm rule, and you'll see that it is........... still going clockwise!

So the answer will be B.

This is really cool concept and I love the set-up

[imda.beast]

hi, is physics getting hsc revision videos. i hope it can be uploaded soon because im struggling with some of the ideas to implementation concepts

[blasonduo]

hi, is physics getting hsc revision videos. i hope it can be uploaded soon because im struggling with some of the ideas to implementation concepts

Yes it is! It might still be a while, but if there is something you don't quite understand, just post it here!

EDIT: Check here for details https://atarnotes.com/forum/index.php?topic=173138.0

EDIT2: THEY ARE OUT NOW! CHECK EM OUT

[seventeenboi]

Hello!!!!!!

"In your study of Q2Q you have performed an investigation to observe radiation emitted from a nucleus using a Wilson Cloud Chamber or a similar detection device. Describe how you carried out your investigation."

What is the most preferable and common answer to this question ??

thanks :^)

[mary123987]

HEY guys just had a quick question ; do you need to know the pauli exclusion principle for ideas to implementation ? or is it just for quanta to quarks ( and if you are wondering my option is medical physics so no i dont need to know it for my otpion)
 thanks a lot
Mary

[bsdfjnlkasn]

HEY guys just had a quick question ; do you need to know the pauli exclusion principle for ideas to implementation ? or is it just for quanta to quarks ( and if you are wondering my option is medical physics so no i dont need to know it for my otpion)
 thanks a lot
Mary

Hey there!

The first exposure I had to Pauli's exclusion principle was in Quanta to Quarks so I think it is safe to say, that no you don't need to know it

[bsdfjnlkasn]

Hey guys!

The answer listed for Q7 is B and I was 99% sure that the answer was D when I was answering..
Also for Q16, I just wanted some clarification. When is the angle that they've given you a distractor? Is it only when the field is into/out of the page. And when, in this situation, do they give you the wrong angle? What does that look like?

Would love some help on these, thank you

[sidzeman]

For this question, does GPE being halved mean the satellite is brought closer to Earth or further away?. I thought it meant closer, since GPE rises as you get further away, but apparently this is not the case. Is it do the with the fact that GPE gets closer to 0 when moved away? I always get confused when they say GPE has increased as I don't know if it means its gotten closer to 0 and further away

Could someone also explain the other questions to me please

[Savas_P]

For this question, does GPE being halved mean the satellite is brought closer to Earth or further away?. I thought it meant closer, since GPE rises as you get further away, but apparently this is not the case. Is it do the with the fact that GPE gets closer to 0 when moved away? I always get confused when they say GPE has increased as I don't know if it means its gotten closer to 0 and further away

Could someone also explain the other questions to me please

1. The GPE is halved use this equation E=-G(m1*m2)/R to see that the radius is doubled, then plug into the force equation F=Gm1m2/r^2 to see that the force will become a quarter of the initial force.

2. Use the right hand grip rule with your thumb pointing down to Y to see the direction of the force.

3. The force is the calculated from the angle between the wire and the magnetic field, you can see that WX is perpendicular to the poles of magnets. The torque is read off the information because it is the angle of the plane and the magnetic field.