HSC Physics Question Thread

[blasonduo]

Quick question: are we allowed to shorten low earth orbits as LEO in our answers. Thanks

If you need to refer to it many times, it'll be best to first write out Low Earth Orbit (LEO) and then continue using LEO afterwards. Just to make sure the marker understands what you mean by it As long as you do that, you'll be sweet!

[Oscar322]

Hi, for those doing/have done the Astrophysics topic, do you think it is necessary to memorise very specific things like the spectral classes and the different types of variables? Thanks

[Blissisignorance]

In the 2015 HSC,
At Q28) the graph in the sample answers has velocity remaining constant for most of AB before falling just before B all the way to just after C. But, I can't understand why velocity isn't dropping during AB too since AB=BC. My graph had velocity falling from A to B, then falling once again to C before being constant.

[dermite]

hi, i need some help as to how to do this qn. The answer given is 3.13ms^-1

[jamonwindeyer]

In the 2015 HSC,
At Q28) the graph in the sample answers has velocity remaining constant for most of AB before falling just before B all the way to just after C. But, I can't understand why velocity isn't dropping during AB too since AB=BC. My graph had velocity falling from A to B, then falling once again to C before being constant.

I agree with your answer Bliss!! You are right - The magnet would be opposing the motion towards it just as much as it would oppose the motion away from it (in terms of the eddy currents generated). I think the sample answer is wrong

hi, i need some help as to how to do this qn. The answer given is 3.13ms^-1

Hey! The centripetal force on the rotating mass carrier is provided by the weight force of the mass carrier below. So:



You substitute and rearrange to find \(v\)

[moq418]

How do you :
Describe quantitatively the force acting on a charge moving through a magnetic field:

F = qvB

[Fergus6748]

How do you :
Describe quantitatively the force acting on a charge moving through a magnetic field:

F = qvB

Heya, are there any values with the question?

[dazza2020]

Hi All,

Just wondering what markers think of integrating option topic knowledge into core answers?
 
E.g. Describe the impact Planck's theories regarding Black Body Radiation had on Scientific Thinking? Beyond the obvious, I read somewhere that De-Broglie explained his wavelength's of electron orbits after learning that waves could be quantised and reading Planck's 1905 papers.

[Fergus6748]

Hi All,

Just wondering what markers think of integrating option topic knowledge into core answers?
 
E.g. Describe the impact Planck's theories regarding Black Body Radiation had on Scientific Thinking? Beyond the obvious, I read somewhere that De-Broglie explained his wavelength's of electron orbits after learning that waves could be quantised and reading Planck's 1905 papers.

Hey, I would assume that they would have no problem with it as they can't take marks or give you marks for info that doesn't relate to the question. If it the info is relevant than by all means go ahead and put it in. The only thing with that is that, even if it is relevant, if the info doesn't really answer or at least forward your answer than all you are doing is spending precious time writing info that may not help you get marks. Hope this helps!!

[Mate2425]

Hey guys, so walking into exam and during the exam should my calc be in RAD or in just degrees?

Thank you!

[sweetiepi]

Hey guys, so walking into exam and during the exam should my calc be in RAD or in just degrees?

Thank you!

For the sciences, you should always have your calculator in degrees.

[phunky]

Hi, I'm a bit confused about this question - how do you work out the poles of the magnets?

[blasonduo]

Hi, I'm a bit confused about this question - how do you work out the poles of the magnets?

The first step is to figure out the direction of the magnetic field (either left to right of right to left)

From the positive terminal you can see that the magnets are going to be electromagnets, you can see that it wraps around the left block in clockwise way, You know it has a SOUTH facing pole (I use the term Nanti-Socks to remember if clockwise is South or North )

To double check, we'll do the other side, from the negative terminal, this time, it is travelling in an ANTI-clockwise way (remember to look at it standing in the middle) This means that the RIGHT block is the NORTH pole. So the magnetic field lines follow from right to left.

The next part is the simple right hand palm rule, as you know the + and - terminals, follow the current lines until the right option works. In this case, B is the only one that rotates clockwise. (Left side coil current goes up (so thumb up!) and magnetic field right to left (so fingers to right) shows the palm upwards and thus it rotating clockwise.

Basically, this question is asking about your ability to figure out electromagnets, As B and D are almost the same, where D's right block is coiled the wrong way!

Hope this helps!

[Mate2425]

Hey could someone please explain why the answer is A in HSC 2016 Q16a?

Thank you.

[Fergus6748]

Hey could someone please explain why the answer is A in HSC 2016 Q16a?

Thank you.

Heya, so basically the loudspeaker is being used in reverse, as the cone of the speaker is being pushed and that is moving the coil. So therefore it is acting as a generator, because it is transfering mechanical energy to electrical energy. The movement of the coil is creating current in the circuit, as according to Lenz's Law. Then you use right hand grip rule to find that current travels from X to Y. Hope this helps!!