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HSC Physics Marathon 2013-2015 Archive (2 Viewers)

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Astraea

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re: HSC Physics Marathon Archive

Describe the Quantum Model of Radiation put forward by Max Planck (2 Marks)
 

Menomaths

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re: HSC Physics Marathon Archive


Calculate the force on the conductor
a)2.3x10-4N
b)2.3x10-2N
c)4.5x10-4N
d)4.5x10-2N
 

Fizzy_Cyst

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re: HSC Physics Marathon Archive

^^ so many students get these types of questions incorrect!!
 

Menomaths

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re: HSC Physics Marathon Archive



how to do dis??
 

Parvee

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re: HSC Physics Marathon Archive



how to do dis??
kepler's 3rd law
since they all orbit the same central body (the sun) GM/4(pi)^2 is constant
So you can equate r1^3/t1^2=r2^3/t2^2
 

Menomaths

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re: HSC Physics Marathon Archive

kepler's 3rd law
since they all orbit the same central body (the sun) GM/4(pi)^2 is constant
So you can equate r1^3/t1^2=r2^3/t2^2
Ahhh thanks Parbee!
Can you also explain the question above above if you're not busy?
 

Parvee

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re: HSC Physics Marathon Archive

Ahhh thanks Parbee!
Can you also explain the question above above if you're not busy?
F=nBILsin(theta)
You need to work out the length of the wire in the field, getting l=0.3/sin(30)=3/5
therefore F=5x10^-4 x 3 x 3/5 x sin(30)= 4.5x10^-4 N
( I think dis is right, its been so long lel)
 

Menomaths

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re: HSC Physics Marathon Archive

Sometimes...I just have retarded moments...
Thanks again Parbee
 

Menomaths

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re: HSC Physics Marathon Archive



too much maffs halp me get through! :(
 

Parvee

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re: HSC Physics Marathon Archive

maybe im derping but uhm all the answers seem wrong, if you work backwards you find that they all give a radius thats x10^15 :/

v=sqrt(GM/r)= sqrt[(6.67x10^-11 x 1.9x10^27)/(7.78x10^11 + 7.15x10^7)]=403.6ms^-1 x (10^-3)/(1/3600)= 1453 kmh^-1



too much maffs halp me get through! :(
Use (delta)x= Ux x t where (delta)x is your range and t is your time of flight
 

Menomaths

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re: HSC Physics Marathon Archive

Wow these questions have a lot of wrong answers then. I did use Ux.t=delta x but none of the answers are correct.
For the first one I also got 403 and for the second one I'm getting 33.25
Good to know I'm not that incompetent(though it wasted a lot of my time) :)
 

Parvee

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re: HSC Physics Marathon Archive

Wow these questions have a lot of wrong answers then. I did use Ux.t=delta x but none of the answers are correct.
For the first one I also got 403 and for the second one I'm getting 33.25
Good to know I'm not that incompetent(though it wasted a lot of my time) :)
403 is in ms^-1, don't forget to convert to kmh^-1

and for 33.25 i guess you would choose the closest which is 33.4
 

JJ345

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re: HSC Physics Marathon Archive

maybe im derping but uhm all the answers seem wrong, if you work backwards you find that they all give a radius thats x10^15 :/

v=sqrt(GM/r)= sqrt[(6.67x10^-11 x 1.9x10^27)/(7.78x10^11 + 7.15x10^7)]=403.6ms^-1 x (10^-3)/(1/3600)= 1453 kmh^-1

Why did you substitute this ^?. Isn't M meant to be mass of the primary ie the sun not the mass of Jupiter itself?
 

Parvee

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Why did you substitute this ^?. Isn't M meant to be mass of the primary ie the sun not the mass of Jupiter itself?
Oh I thought we're assuming an object is orbiting jupiter at the given distance
 

Parvee

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re: HSC Physics Marathon Archive

I think they're meant to be in km/s ?--> I'm getting 13.1 km/s
If it is orbiting the sun then this is correct (even though they didn't give the mass of the sun :L)
 

Menomaths

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re: HSC Physics Marathon Archive

Yeah, can you explain why :D?
 
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