HSC Physics Marathon 2013-2015 Archive (2 Viewers)

[kawaiipotato]

re: HSC Physics Marathon Archive

And why is A and C the same lol

 

[anomalousdecay]

re: HSC Physics Marathon Archive

If i used right hand grip rule for A wouldn't it mean the magnetic field goes from left to right? Allowing it to rotate clockwise too

Yep but due to the wiring orientation, the rotor will rotate anti-clockwise. Use the palm rule to determine the force on the each side of the rotor.

And why is A and C the same lol

no no no

Look carefully at the wiring on the right side. For A and C, the wiring on the right side goes in different directions, so your fingers should curl in different directions too. The same comparison can be made between B and D.

 

[godofindolence]

re: HSC Physics Marathon Archive

If i used right hand grip rule for A wouldn't it mean the magnetic field goes from left to right? Allowing it to rotate clockwise too

http://www.schoolphysics.co.uk/age1...netism/text/Electromagnet_polarity/index.html
Don't know shit so I just use the cools arrow things

 

[kawaiipotato]

re: HSC Physics Marathon Archive

Yep but due to the wiring orientation, the rotor will rotate anti-clockwise. Use the palm rule to determine the force on the each side of the rotor.



no no no

Look carefully at the wiring on the right side. For A and C, the wiring on the right side goes in different directions, so your fingers should curl in different directions too. The same comparison can be made between B and D.

stared at it and it just looks like the negative terminals go on the same end in A and C...

 

[TQuadded]

re: HSC Physics Marathon Archive

this shit tripped me out yesterday, I got a reason to why it's B but am not sure if it's legit lol. I pretty much used the right hand grip rule on the windings to determine the polarity of the magnets, then used right hand palm rule to determine whether the side of the coil was going up or down

wot

 

[atargainz]

re: HSC Physics Marathon Archive

stared at it and it just looks like the negative terminals go on the same end in A and C...

if you follow the wire and think about a physical image, the negative terminal for A is coming out form underneath and coming from above in C, changes your right hand grip rule

 

[anomalousdecay]

re: HSC Physics Marathon Archive

stared at it and it just looks like the negative terminals go on the same end in A and C...

All good. I've made the same mistake before.

 

[anomalousdecay]

re: HSC Physics Marathon Archive

No-one got this one last year. Try it out now!

Also, what direction does the wire travel in?

Show working for formula with a simple explanation of each part (dw about getting the actual value, just worry about getting the formula).

 

[godofindolence]

re: HSC Physics Marathon Archive

No-one got this one last year. Try it out now!

Is that a rail gun :OOOO

 

[anomalousdecay]

re: HSC Physics Marathon Archive

Is that a rail gun :OOOO

Yes!

 

[kawaiipotato]

re: HSC Physics Marathon Archive

I just realised it. I thought the main thing was that in A the right wire went under the left one twice and for C it did it twice.. didn't see that one went under and the other was over

 

[godofindolence]

re: HSC Physics Marathon Archive

is it BIdt/M away from G

 

[anomalousdecay]

re: HSC Physics Marathon Archive

is it BIdt/M away from G

ye

next question

State the differences in the operation of solid state and thermionic devices.

or if you are up for writing up a bit more for me to criticise:

Describe differences between solid state and thermionic devices.

 

[atargainz]

re: HSC Physics Marathon Archive

F=BIL=ma, a=ILB/m

v=u+at, u=0, v=ILBt/m

Sub t=100ms? to the right (RHPR)

- nvm got beaten to it

 

[godofindolence]

re: HSC Physics Marathon Archive

ye

next question

State the differences in the operation of solid state and thermionic devices.

or if you are up for writing up a bit more for me to criticise:

Describe differences between solid state and thermionic devices.

Alright

Solid state drives are transistor based technology which uses the semiconductors as its basis of operation. By providing current, circuits can be switched on and off to store and manipulate large amounts of data.
Thermionic devices uses the property of cathode ray tubes (the ability to for the electron to carry current when heated from the cathode) to accomplish similarly tasks.

Thermionic devices however are large, bulky, fragile and takes time to 'warm up' before usage. Thus, they cost more to maintain, uses much more power and produce large amounts of waste heat. Transistors on the other hand are small, cheap, fast, reliable and produce little heat, making it a far more attractive option for circuits.

 

[astroman]

re: HSC Physics Marathon Archive

guys what is hardest type of projectile motion question they can ask?

 

[InteGrand]

re: HSC Physics Marathon Archive

guys what is hardest type of projectile motion question they can ask?

They don't get too hard generally. Try the Q.27 of 2012 HSC Physics paper (Page 23 here: http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2012exams/pdf_doc/2012-hsc-exam-physics.pdf ), that's about as hard as they tend to be in HSC Physics.

 

[malcolm21]

re: HSC Physics Marathon Archive

wtf is this question the answers showed 1 line of working for 4 marks, there was a 9.8 that came out of nowhere:

 

[InteGrand]

re: HSC Physics Marathon Archive

wtf is this question the answers showed 1 line of working for 4 marks, there was a 9.8 that came out of nowhere:

 

[godofindolence]

re: HSC Physics Marathon Archive

wtf is this question the answers showed 1 line of working for 4 marks, there was a 9.8 that came out of nowhere:

Yea this seems wrong with the 7