HSC Physics Question Thread

[RuiAce]

If I want to emphasise the size of a number, I don't think the index does it justice. Like, 100 Billion FREAKING WATTS MATE! I like the "oomph" 

Wooooow calm down of course i knew that

[jamonwindeyer]

Wooooow calm down of course i knew that

Ahaha see? The oomph is nice 

[smiley2101]

Ahh I see, thanks heaps! Also, I'm writing notes at the moment and was just wondering what sources you guys used to collate notes because reading your guides you have included information on Rayleigh jeans law etc and I can't find any textbook that mentions this information but I really like having an in depth understanding so just wanted to know what sources you guys used?

[jamonwindeyer]

Ahh I see, thanks heaps! Also, I'm writing notes at the moment and was just wondering what sources you guys used to collate notes because reading your guides you have included information on Rayleigh jeans law etc and I can't find any textbook that mentions this information but I really like having an in depth understanding so just wanted to know what sources you guys used?

For me, Rayleigh Jeans came from uni. I've supplemented my HSC knowledge with my study at uni in a few places, you definitely don't need that for the HSC unless you want it! 

For reference though, in the HSC I primarily used:

• -Textbooks
• -Notes from my Teacher (they were amazing)
• -Hyperphysics
• -Youtube Videos on occasion if I happened to find something good

I'm a big believer in efficient study, only knowing what is necessary to get a Band 6 for the subject. I wrote these Physics notes with that in mind, condensed everything I know into exactly what you need to do well in the course, no fluff  might be of interest to you! (forgive me shameless self advertising)

EDIT: These notes are freaking amazing, Jamon's just too modest. I literally tutor from them, and they have everything you need (plus great donut-related diagrams!). xoxo Jake

[Swagadaktal]

EDIT: These notes are freaking amazing, Jamon's just too modest. I literally tutor from them, and they have everything you need (plus great donut-related diagrams!). xoxo Jake

LMAO AHAHAHA OMG
I love you guys omg

[RuiAce]

LMAO AHAHAHA OMG
I love you guys omg

Yea I cracked up at that as well.

[Neutron]

Hey guys!

Trying to do some revision but I'm just dying instead.. Anyway, with Planck's quantum theory, he hypothesized that the black body emission curve was independent of the material of the blackbody. So basically the radiations emitted from copper and aluminium would produce the same curve, right? I'm just kinda confused because copper is a better thermal and electrical conductor than aluminium, and if Planck proposed that the source of radiation is FROM the oscillations of the atoms making up the material how can the type of atom (i.e. material) not have an effect on the subsequent radiation? Sorry if that sounded confusing ah..

Thanks guys!

Neutron

[jamonwindeyer]

Hey guys!

Trying to do some revision but I'm just dying instead.. Anyway, with Planck's quantum theory, he hypothesized that the black body emission curve was independent of the material of the blackbody. So basically the radiations emitted from copper and aluminium would produce the same curve, right? I'm just kinda confused because copper is a better thermal and electrical conductor than aluminium, and if Planck proposed that the source of radiation is FROM the oscillations of the atoms making up the material how can the type of atom (i.e. material) not have an effect on the subsequent radiation? Sorry if that sounded confusing ah..

Thanks guys!
Neutron

Hey there Neutron! Okay, I'm happy to be corrected on this answer because I'm not 100% sure, but here we go regardless 

Yes, copper is a better thermal and electrical conductor than aluminium. However, the black body radiation curves come from the thermal vibrations of the black body. So, even though copper is a better thermal conductor, all this means is that it is "easier" for copper to reach higher temperatures, so the black body radiation curve can shift to higher frequencies (say, visible light).

Although the atomic structure of the materials are different, black body radiation is thermal radiation. All atoms respond in the same way to thermal energy, by vibrating, and thus the radiation does not depend on the type of atom.

I hope that answer makes a little bit of sense, definitely happy for someone to give a better one 

[RuiAce]

Hey there Neutron! Okay, I'm happy to be corrected on this answer because I'm not 100% sure, but here we go regardless 

Yes, copper is a better thermal and electrical conductor than aluminium. However, the black body radiation curves come from the thermal vibrations of the black body. So, even though copper is a better thermal conductor, all this means is that it is "easier" for copper to reach higher temperatures, so the black body radiation curve can shift to higher frequencies (say, visible light).

Although the atomic structure of the materials are different, black body radiation is thermal radiation. All atoms respond in the same way to thermal energy, by vibrating, and thus the radiation does not depend on the type of atom.

I hope that answer makes a little bit of sense, definitely happy for someone to give a better one 

Seems legit from a chemist's point of view as well.

Exactly. @Neutron - Just being a better thermal conductor only means it can absorb heat better.

Temperature can be seen as a measure of how much kinetic energy the particles are carrying overall. If the particles are placed in rooms with similar temperature, the kinetic energy of the particles will be around the same, making it equally easy/difficult for photons to hit electrons.

Conductance is also a measure of how easily electrons can flow THROUGH the substance in a circuit. It has nothing to do with the photoelectric effect, where they are ejected off.

[smiley2101]

Hi again! Okay so I was doing a trial physics exam and one of the questions was stated as follows;
State how Hertz was able to determine the frequency of his e-m radiation

I thought that he just used an oscillator of known frequency yet the marking guideline states this : -"Correct statement involving resonance; Hertz used the condition giving the frequency when a circuit is in resonance and sparking optimally. "

I have never come across resonance in the hsc course.....? help    thank you so much

[jamonwindeyer]

Hi again! Okay so I was doing a trial physics exam and one of the questions was stated as follows;
State how Hertz was able to determine the frequency of his e-m radiation

I thought that he just used an oscillator of known frequency yet the marking guideline states this : -"Correct statement involving resonance; Hertz used the condition giving the frequency when a circuit is in resonance and sparking optimally. "

I have never come across resonance in the hsc course.....? help    thank you so much

Hmm, although I definitely know that resonance is applicable in this situation, I don't think it is necessary knowledge for the HSC either! I've definitely never seen it in any HSC textbook. Which Trial was this? Very curious indeed 

Anyway, resonance in general is the idea that an oscillatory system can be made to oscillate at greater amplitudes when driven by external forces at a specific frequency (called the resonant frequencies). This is a mouthful, but you'll most definitely be familiar with the idea. Know the myth about opera singers breaking glasses with their voices? Based on this idea, the idea that singing at the resonant frequency of the glass will cause it to vibrate and break. Resonant frequencies are everywhere, anything that you can get "into a rhythm" is really just going at the resonant frequency.

Electrical resonance is similar, it is the idea that circuits will exhibit a greater response at specific input frequencies. In this situation, Hertz would absolutely have noticed the most sparking at the resonant frequency of the spark gaps. Why? Purely because the circuits, for reasons to complex to discuss here, just like that frequency. Hertz would use that frequency to make the sparking most obvious.

I hope this helps! Very interesting that that showed up in the criteria! 

[Sahar8642]

Hey,
Does anyone have detailed notes on the practicals as we never covered them in school properly. As in, we watched while the teacher did the prac and didn't do proper write-ups
Thanks!

[Sahar8642]

Hey,
does anyone have concise notes on this dotpoint:
process information to discuss Einstein and Planck’s differing views about whether science research is removed from social and political forces
Thanks!

[jamgoesbam]

Didn't know how to do these questions ... could someone please explain them? Would be much appreciated! Thanks in advanced

[conic curve]

Found this question on the net (if anyone's willing to try it out obviously)

A motor vehicle has a kerb weight of 1500kg and is moving with a velocity of 50 kilometres per hour. The mass of the driver is 80kg and there are no other passengers in the motor vehicle. This motor vehicle collides head on with a concrete wall (2 metres high and 1 metre thick) and comes to rest in 0.15 seconds.

Critically evaluate the change of energy which occurs during this collision.