HSC Physics Marathon 2013-2015 Archive (4 Viewers)

Status
Not open for further replies.

Astraea

Member
Joined
Apr 3, 2012
Messages
40
Gender
Female
HSC
2013
re: HSC Physics Marathon Archive

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

Menomaths

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
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

Owner @ Sigma Science + Phys Goat
Joined
Jan 14, 2011
Messages
1,212
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
re: HSC Physics Marathon Archive

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

Menomaths

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
re: HSC Physics Marathon Archive



how to do dis??
 

Parvee

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
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

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
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

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
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

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
re: HSC Physics Marathon Archive

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

Menomaths

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
re: HSC Physics Marathon Archive



too much maffs halp me get through! :(
 

Parvee

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
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

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
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

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
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

Member
Joined
Apr 27, 2013
Messages
78
Gender
Female
HSC
N/A
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

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
re: HSC Physics Marathon Archive

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

(╯°□°)╯︵ ┻━┻
Joined
Apr 4, 2011
Messages
1,077
Gender
Female
HSC
2012
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

Exaı̸̸̸̸̸̸̸̸lted Member
Joined
Jul 9, 2013
Messages
2,373
Gender
Male
HSC
2013
re: HSC Physics Marathon Archive

Yeah, can you explain why :D?
 
Status
Not open for further replies.

Users Who Are Viewing This Thread (Users: 0, Guests: 4)

Top