• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

HSC Physics Marathon 2013-2015 Archive (7 Viewers)

Status
Not open for further replies.

Drsoccerball

Well-Known Member
Joined
May 28, 2014
Messages
3,650
Gender
Undisclosed
HSC
2015
re: HSC Physics Marathon Archive

mv = mo/sqrt(1-v^2/c^2)
When travelling at relativistic speeds, outside observers will see that the mass of the proton increases
So sub mo = mass of proton (from data sheet) and you should get a mass larger than the stated mass
As mass increases as you approach relativistic speeds from an inertial frame of reference. m0 is in the inertial fram while mv is in the other
 

el_manu

Member
Joined
Feb 12, 2014
Messages
126
Location
Sydney, Australia
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

The planet Neptune orbits the sun at an average distance of 4.5 x 1012 m with a period of 5.2 x 109 s. The sun has a mass of 2.0 x 1030 kg. Show that Neptune’s orbit obeys Kepler’s Law of Periods.
 

astroman

Well-Known Member
Joined
May 12, 2014
Messages
7,069
Location
Las Vegas
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

QUESTION) the assumption that acceleration would be constant and partly is incorrect, using the conservation of momentum explain why? (3m)
 

turntaker

Well-Known Member
Joined
May 29, 2013
Messages
3,908
Gender
Undisclosed
HSC
2015
re: HSC Physics Marathon Archive

QUESTION) the assumption that acceleration would be constant and partly is incorrect, using the conservation of momentum explain why? (3m)
is that the whole question
 

el_manu

Member
Joined
Feb 12, 2014
Messages
126
Location
Sydney, Australia
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

The planet Neptune orbits the sun at an average distance of 4.5 x 1012 m with a period of 5.2 x 109 s. The sun has a mass of 2.0 x 1030 kg. Show that Neptune’s orbit obeys Kepler’s Law of Periods.
is the average distance in the question the same as 'r' in Kepler's Law equation
 

astroman

Well-Known Member
Joined
May 12, 2014
Messages
7,069
Location
Las Vegas
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

guys i got a mind blank, someone clarify:

Einstein's prediction that time would slow down at relativistic speeds could not be tested until after the time the theory was first proposed. Describe an experiment performed to confirm Einstein's prediction.
 

el_manu

Member
Joined
Feb 12, 2014
Messages
126
Location
Sydney, Australia
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

guys i got a mind blank, someone clarify:

Einstein's prediction that time would slow down at relativistic speeds could not be tested until after the time the theory was first proposed. Describe an experiment performed to confirm Einstein's prediction.
2 precise clocks. One was kept on ground, one was put on a plane that flew around the world. The two clocks were initially synchronised, but were out of synch after experiment. This shows time passes different in different time frames.
 

el_manu

Member
Joined
Feb 12, 2014
Messages
126
Location
Sydney, Australia
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

guys i got a mind blank, someone clarify:

Einstein's prediction that time would slow down at relativistic speeds could not be tested until after the time the theory was first proposed. Describe an experiment performed to confirm Einstein's prediction.
OR... the muon one.

(muons are tiny particles that are 'created' when cosmic rays hit our upper atmosphere.) They then travel towards the ground at close to speed of light. Muons are unstable and have a short lifetime (2.2x10 to the -6) when stationary. If we know how many are produced and how long on average they live and how fast they travel, we can predict how many of them will get to the ground. If special relativity is ignored we get a prediction MUCH LESS than the number of muons we measure. THis implies that their lifetime is actually LONGER...this supports time dilation.

I haven't described the experiment but I mentioned what it was.
 

el_manu

Member
Joined
Feb 12, 2014
Messages
126
Location
Sydney, Australia
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

The planet Neptune orbits the sun at an average distance of 4.5 x 1012 m with a period of 5.2 x 109 s. The sun has a mass of 2.0 x 1030 kg. Show that Neptune’s orbit obeys Kepler’s Law of Periods.
Is the average distance given the same as 'r' in Kepler's law of equation?
 

astroman

Well-Known Member
Joined
May 12, 2014
Messages
7,069
Location
Las Vegas
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

donno if anyone does astro but how do u calculate color index?
 

Drsoccerball

Well-Known Member
Joined
May 28, 2014
Messages
3,650
Gender
Undisclosed
HSC
2015
re: HSC Physics Marathon Archive

2 precise clocks. One was kept on ground, one was put on a plane that flew around the world. The two clocks were initially synchronised, but were out of synch after experiment. This shows time passes different in different time frames.
The official name is Atomic clocks
 

PhysicsMaths

Active Member
Joined
Dec 9, 2014
Messages
179
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Is the average distance given the same as 'r' in Kepler's law of equation?
Yes, in this case, r represents the distance from the centre of the sun to Neptune (orbital distance)
 

Rhinoz8142

Well-Known Member
Joined
Jul 25, 2013
Messages
1,334
Location
Sydney
Gender
Male
HSC
2014
Uni Grad
2018
re: HSC Physics Marathon Archive

Explain this picture

 

astroman

Well-Known Member
Joined
May 12, 2014
Messages
7,069
Location
Las Vegas
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Explain this picture

the mirror is 10 years away, it takes 10 years for the light to reach and 10 years for it to return, hence you will see the image as if it would appear 20 years ago.
 

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

Explain how an AC induction motor operates (5 marks)
 

Kaido

be.
Joined
Jul 7, 2014
Messages
798
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

- 3 phase AC into the stators that creates a rotating magnetic field
- By f-law, the changing mag flux due to the rotating mag field induces a current in the rotor coils
- By l-law, the current is in a direction such that the mag field it induces opposes the original change in flux the created it
- thus, the induced mag field interacts with the rotating mag-field and the rotor begins to spin as it 'chases' the rotating mag field

how much would this score if i wrote this as it is
 
Status
Not open for further replies.

Users Who Are Viewing This Thread (Users: 0, Guests: 7)

Top