# Thread: HSC Physics Marathon 2016

1. ## Re: HSC Physics Marathon 2016

*facepalm*

Leave some of the InteGrand jokes out in the physics marathon please, that's only gonna add to confusion in 2016ers.

2. ## Re: HSC Physics Marathon 2016

Originally Posted by porcupinetree
For (2), surely a planet would not even be able to form in this alternate universe? (at least via accretion?) Or is this simply hypothetical?
Yes I thought of that and hoped someone would pick that up its a hypothetical situation like if that planet the moment intwgrand approaches just appears out of thin space.

3. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
*facepalm*

Leave some of the InteGrand jokes out in the physics marathon please, that's only gonna add to confusion in 2016ers.
Its do-able with current space knowledge I'm not making these questions just for the jokes theyre legit questions one could solve.

4. ## Re: HSC Physics Marathon 2016

Originally Posted by Drsoccerball
Its do-able with current space knowledge I'm not making these questions just for the jokes theyre legit questions one could solve.
Maybe make them without Integrand references then.
edit: or any references to BoS members e.g. Ekman or Gabriel Moussa.

5. ## Re: HSC Physics Marathon 2016

Originally Posted by dan964
Maybe make them without Integrand references then.
Lol, inb4 Ekman or Gabriel Moussa references instead. :P

6. ## Re: HSC Physics Marathon 2016

Seeing as there's no question:
Observer A sits in the middle of a train traveling at high speed past a railway station. Observer B stands on the station platform. Lightning strikes the front and back of the train at the moment observer A passes observer B. Analyse the statements of both observers regarding the order of the lightning strikes. (5)

7. ## Re: HSC Physics Marathon 2016

Originally Posted by Drsoccerball
You have the right idea but the purpose behind multi-rockets isn't what you said it was. For example why can't we just use a bigger fuel tank to reach the same place? It actually isn't to increase acceleration but rather to reduce it! This is especially useful in manned rockets where there needs to be a limit on g force to maximise the survival potential. $G Force = 1+ \frac{a}{g}$ Therefore by using multi-staged rockets we can stop the acceleration or reduce it to reasonable measures for the on board passengers. * Add some bs at beginning and end about space travel*
Thats how I got my band 6 in physics.
I am
Gabriel Moussa

8. ## Re: HSC Physics Marathon 2016

Originally Posted by InteGrand
Lol, inb4 Ekman or Gabriel Moussa references instead. :P
I heard my name being called in the wind.
My name.
is Gabriel Moussa

9. ## Re: HSC Physics Marathon 2016

BUMP

Originally Posted by wiliaamnguuyen
Seeing as there's no question:
Observer A sits in the middle of a train traveling at high speed past a railway station. Observer B stands on the station platform. Lightning strikes the front and back of the train at the moment observer A passes observer B. Analyse the statements of both observers regarding the order of the lightning strikes. (5)

.

11. ## Re: HSC Physics Marathon 2016

Originally Posted by MilkyCat_
As the train is travelling at a very high speed (assuming this is near light speed) events in one frame of reference that seem simultaneous may not appear simultaneous in another frame of reference. For observer A, the lightning strikes appear to be simultaneous as the light has to travel the same distance to reach the middle of the train. For observer B, however, the lightning strikes do not occur simultaneously, as the light from the front of the train will have to travel a further distance to reach the observer, due to the speed of the train. This demonstrates how simultaneity is relative to the observer, as observer A views the event to be simultaneous and observer B sees the lightning strike the back of the train before the front.

12. ## Re: HSC Physics Marathon 2016

wait disregard my answer it's wrong

13. ## Re: HSC Physics Marathon 2016

As the train is travelling at a very high speed (assuming this is near light speed) events in one frame of reference that seem simultaneous may not appear simultaneous in another frame of reference. Observer B (on the platform) will observe that the events are simultaneous, as the light from the lightning will travel the same distance to reach them. Observer A (on the train) will observe the lightning to strike the front of the train before the back of the train. This is because they are travelling near light speed, which means as they travel the distance from the front of the train is shortened, and likewise lengthened from the back. As the speed of the light is a constant, the time taken for the light to reach Observer A is shortened from the front of the train and increased from the back, therefore not occurring simultaneously. This demonstrates how simultaneity is relative to the observer.

14. ## Re: HSC Physics Marathon 2016

Originally Posted by MilkyCat_
As the train is travelling at a very high speed (assuming this is near light speed) events in one frame of reference that seem simultaneous may not appear simultaneous in another frame of reference. Observer B (on the platform) will observe that the events are simultaneous, as the light from the lightning will travel the same distance to reach them. Observer A (on the train) will observe the lightning to strike the front of the train before the back of the train. This is because they are travelling near light speed, which means as they travel the distance from the front of the train is shortened, and likewise lengthened from the back. As the speed of the light is a constant, the time taken for the light to reach Observer A is shortened from the front of the train and increased from the back, therefore not occurring simultaneously. This demonstrates how simultaneity is relative to the observer.
I'm a bit out of shape to mark physics responses right now, but do mention further consequences such as time dilation where appropriate instead of stating what happens. The examiners do like to see technical terminology. Just like you mentioned relativity of simultaneity in the last sentence.

15. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
I'm a bit out of shape to mark physics responses right now, but do mention further consequences such as time dilation where appropriate instead of stating what happens. The examiners do like to see technical terminology. Just like you mentioned relativity of simultaneity in the last sentence.
Why would you have to mention time dilation? Time dilation is almost irrelevant to the situation that is being described in this question.

Also @ MilkyCat_ are you implying that if the train wasn't travelling near the speed of light then the relativity of simultaneity does not hold true?
You should also explicitly state that the speed of light is constant in all inertial frames of reference. You should also state why this situation is an example of light being perceived from two different inertial frames of reference.

16. ## Re: HSC Physics Marathon 2016

At the time I was meant to say length contraction.

Except, after rereading the answer I realised I must've misinterpreted something the first time I read it.

Originally Posted by KX
Also @ MilkyCat_ are you implying that if the train wasn't travelling near the speed of light then the relativity of simultaneity does not hold true?
You should also explicitly state that the speed of light is constant in all inertial frames of reference. You should also state why this situation is an example of light being perceived from two different inertial frames of reference.
Although the wording could be better to cater for how it still holds, I haven't found the examiners to be fussy over the fact it is essentially negligible at non-relativistic speeds.

17. ## Re: HSC Physics Marathon 2016

A student sets up the following apparatus.

Two wires are connected to a power box (6V) on one end, and a strip of aluminium foil (resistance = 1Ω) on the other. The aluminium fold bends on top of itself in this circuit. (Picture a C shape the foil is making.)

When the switch was turned on, momentarily the aluminium foil appeared to expand.

a) What happened to the power box once the switch got flicked and why? (2)
b) Carefully explain (with or without use of a diagram) why the aluminium foil expanded. (4)
c) The average seperation distance of the foil was 3mm. Calculate the force each side of the foil exerted on each other. (3)

18. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
A student sets up the following apparatus.

Two wires are connected to a power box (6V) on one end, and a strip of aluminium foil (resistance = 1Ω) on the other. The aluminium fold bends on top of itself in this circuit. (Picture a C shape the foil is making.)

When the switch was turned on, momentarily the aluminium foil appeared to expand.

a) What happened to the power box once the switch got flicked and why? (2)
b) Carefully explain (with or without use of a diagram) why the aluminium foil expanded. (4)
c) The average seperation distance of the foil was 3mm. Calculate the force each side of the foil exerted on each other. (3)
lel burnt my hand doing this experiment.

19. ## Re: HSC Physics Marathon 2016

The idea of the question is good but the way you wrote out the question is horribly confusing.

20. ## Re: HSC Physics Marathon 2016

I know. I may include a diagram of the apparatus later and attempt a rewording.

21. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
I know. I may include a diagram of the apparatus later and attempt a rewording.
M9, you never did

22. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
A student sets up the following apparatus.

Two wires are connected to a power box (6V) on one end, and a strip of aluminium foil (resistance = 1Ω) on the other. The aluminium fold bends on top of itself in this circuit. (Picture a C shape the foil is making.)

When the switch was turned on, momentarily the aluminium foil appeared to expand.

a) What happened to the power box once the switch got flicked and why? (2)
b) Carefully explain (with or without use of a diagram) why the aluminium foil expanded. (4)
c) The average seperation distance of the foil was 3mm. Calculate the force each side of the foil exerted on each other. (3)
Still trying to understand what these mean lol

23. ## Re: HSC Physics Marathon 2016

Originally Posted by DatAtarLyfe
M9, you never did
I got lazy. I'll do one today lol.

24. ## Re: HSC Physics Marathon 2016

Originally Posted by leehuan
I got lazy. I'll do one today lol.
Well can you post another qu. we can do whilst you work that out?

25. ## HSC Physics Marathon 2016

And if you're still having trouble the foil looks like this

TBH - Does it matter? NO. It just had to be a thin sheet of electroconductive material.

Sent from my iPhone using Tapatalk

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