HSC Physics Question Thread

[jakesilove]

Is this Quanta to Quarks?

Yup it is! I did medical physics, so I can't be of much use for that option unfortunately... except for the Quantum physics I've done at Uni!

[Syndicate]

does nuclear fusion also release energy?

Decided to jump in the conversation

For two smaller atoms to fuse, they require a lot of energy and high temperatures. So, when they are fused together(for instance two hyrdogen atoms fuse together to produce deutrium), there is excess energy left over, which is emitted by the nuclei in the form of gamma radiation.

[conic curve]

Yup it is! I did medical physics, so I can't be of much use for that option unfortunately... except for the Quantum physics I've done at Uni!

Did jamon study quanta to quarks?

Also did you study industrial chemistry?

[jamonwindeyer]

Did jamon study quanta to quarks?

Also did you study industrial chemistry?

I studied Medical Physics just like Jake did, but I bet there are lots of people hanging around who did Quanta 

[conic curve]

I studied Medical Physics just like Jake did, but I bet there are lots of people hanging around who did Quanta 

Damm.....What if we ask things in Quanta to Quarks which require a high level of understanding? (I don't think I will be but I think others might)

[jamonwindeyer]

Damm.....What if we ask things in Quanta to Quarks which require a high level of understanding? (I don't think I will be but I think others might)

We hope that someone else can answer!! Jake and I have some background knowledge with regard to the content, Jake more than me, so we'll handle what we can, otherwise we hope others can help out 

[RuiAce]

Afraid that I can't assist this problem too much since I did astro

[conic curve]

We hope that someone else can answer!! Jake and I have some background knowledge with regard to the content, Jake more than me, so we'll handle what we can, otherwise we hope others can help out 

I hope that as well

[jakesilove]

I hope that as well

I've done a fair amount of the Quanta curriculum, so I'm sure we'll be okay

[Loki98]

Need help with this question,
The distance to the star alpha centuari is 4.367 light years as measured from Earth. Using a relevant equation, explain how a rocket could complete the journey from earth to alpha centuari in 3.28 years.

[jamonwindeyer]

Need help with this question,
The distance to the star alpha centuari is 4.367 light years as measured from Earth. Using a relevant equation, explain how a rocket could complete the journey from earth to alpha centuari in 3.28 years.

Hey Loki! The equation that this question mentions is the length contraction formula:



Essentially what is happening here is that if the rocket travels at a relativistic speed, the distance between the earth and Alpha Centauri (with respect to earth) contracts with respect to the frame of reference of the rocket. That is, the astronauts actually would believe the distance to be shorter due to length contraction. Thus, with respect to the earth, the astronauts would actually arrive earlier than they would have if we didn't take length contraction into account, because the distance travelled with respect to the rocket is shorter.

The answer to your question would explain that principle, preferably being a little more succinct  Does that make sense?

[Loki98]

Hey Loki! The equation that this question mentions is the length contraction formula:



Essentially what is happening here is that if the rocket travels at a relativistic speed, the distance between the earth and Alpha Centauri (with respect to earth) contracts with respect to the frame of reference of the rocket. That is, the astronauts actually would believe the distance to be shorter due to length contraction. Thus, with respect to the earth, the astronauts would actually arrive earlier than they would have if we didn't take length contraction into account, because the distance travelled with respect to the rocket is shorter.

The answer to your question would explain that principle, preferably being a little more succinct  Does that make sense?

Yea it makes sense now. But how would i prove that the time taken would be 3.28 years?

[conic curve]

I've done a fair amount of the Quanta curriculum, so I'm sure we'll be okay

Fantastic 

[jamonwindeyer]

Yea it makes sense now. But how would i prove that the time taken would be 3.28 years?

Oh, good point! This is a little beyond what would be asked in the HSC, but it would look like this. First, you'd use the speed equation:



This allows you to link the length quantities in the equation above to the times given in the question. You get:



We substitute those quantities into the length contraction formula and that lets us solve for the velocity:



I skipped a few steps in that algebraic working, let me know if you need me to clarify it, but this should give you the direction! 

This working is subject to inaccuracy, I've never actually done this calculation before! However, the answer seems sensible to me, and note that this is pretty bloody quick  again, it is unlikely you'd be asked to specifically provide the calculation in the HSC, and I think the question was looking for something a little more general 

[RuiAce]

Oh, good point! This is a little beyond what would be asked in the HSC, but it would look like this. First, you'd use the speed equation:



This allows you to link the length quantities in the equation above to the times given in the question. You get:



We substitute those quantities into the length contraction formula and that lets us solve for the velocity:



I skipped a few steps in that algebraic working, let me know if you need me to clarify it, but this should give you the direction! 

This working is subject to inaccuracy, I've never actually done this calculation before! However, the answer seems sensible to me, and note that this is pretty bloody quick  again, it is unlikely you'd be asked to specifically provide the calculation in the HSC, and I think the question was looking for something a little more general 

Using S=D/t does pop around in the HSC I think. It's pretty rare though because it targets high band 5 in my opinion - have to know when to apply what formula, and in what order to apply them.