HSC Physics Marathon 2013-2015 Archive (3 Viewers)

[Drsoccerball]

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

 

[turntaker]

re: HSC Physics Marathon Archive

What is frame

 

[el_manu]

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]

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]

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

 

[astroman]

re: HSC Physics Marathon Archive

is that the whole question

yea the wording is a bit wierd

 

[PhysicsMaths]

re: HSC Physics Marathon Archive

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

? my calculation is correct.

 

[Drsoccerball]

re: HSC Physics Marathon Archive

? my calculation is correct.

your explanation wasn't.

 

[el_manu]

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]

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]

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]

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]

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]

re: HSC Physics Marathon Archive

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

 

[Drsoccerball]

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]

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]

re: HSC Physics Marathon Archive

Explain this picture

 

[astroman]

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]

re: HSC Physics Marathon Archive

Explain how an AC induction motor operates (5 marks)

 

[Kaido]

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