Multiple Choice (Compiled Answers) (1 Viewer)

[Constip8edSkunk]

Originally posted by walla
ummmm....blocking uv rays has a lot to do with the photoelectric effect. the radio waves are low frequency hence low energy and cannot cause sparking.....uv are high frequency, high energy, and hertz put the glass there inadvertently blocking the uv and thus reducing the electrons released. that is actually what hertz did and is how he first observed the photoelectric effect (without realising it).

i don't know if b or d is right but don't make claims like "b has nothing to do with the photoelectric effect"

haha i know what you mean, yeah i just desperately want D to be correct i dont want to lose any more marks

 

[ghoolz]

mine:
1B
2A
3B
4A
5D
6B
7D
8B
9C
10A
11B
12D
13D
14D
15A

As with 14 the glass DOES stop UV radiation and therefore the spark became less BUT this was concluded AFTER. Hertz's OBSERVATIONS were that the spark length was less. It was after they worked out why.

Question 5 says in the first paragraph last sentence (last line) the on board clock said ten years. The next paragraph says the clock on earth ... what time elsapsed on it. But from the astronauts view from the space ship the last part is confusing, but I still think its D.

I done question 8 the same as dnt stop runnin but now realise that it is wrong.

 

[B.Rabbit]

that 25:1 question... Thats so FUCKING STUPID... WHY THE #@%did they state the whole question in primary:secondary then for answer make it secondary to primary ??? WTF is the point seriously... i worked all the shit out and got it wrong by putting 1:25 aswell... thx BOS u dumb fucks test physics not how carefully we examine EACH WORD in a question... BLEED BITCH BLEEEEEED

 

[McDaddy]

lol, it's only one mark dude. I actually did get that one right but I was stupid enough to put a) instead of b) for the 1st question *doh*.

 

[william]

I got all right

 

[soxon]

I believe 5 is d)

Relativity's twin paradox states that the twin at c will age less. Think of minutes instead of years, after a short time twin on c would age a couple of minutes and twin on earth would ages more than twin on c right? so then twin on earth's time is greater than twin on c...

thinking now instead of a short time, 10 minutes on the ship has past, greater than 10 minutes on earth has past. therefore the earth has sped up relative to the ship, time on earth > 10 minutes

 

[Rahul]

12/15
no. 15 seemed easy, but didnt have time left and guessed.

multiple choiice is my weakest

 

[soxon]

14/15

 

[dnt stop runnin]

man i think multiple choie is gonna fuk me up hard

 

[Affinity]

so 5 is B right? I am pretty sure

 

[Rahul]

yep i got B, certain of it.

 

[Affinity]

q5 is B, I can bet life on it.

You're missing the whole point of relativity, first you have to choose your frame of reference, and from the question, your frame of reference would be the spaceship since it's asking you what is seen on the spaceship. hence the spaceship is the 'Stationary' frame and the earth is moving away from it at 0.8c

and to any observer, time passes fastest in his/her OWN inertial frame and slower in frames moving relative to him or her.

think of the muon example if you are not convinced.

Originally posted by soxon
I believe 5 is d)
Relativity's twin paradox states that the twin at c will age less. Think of minutes instead of years, after a short time twin on c would age a couple of minutes and twin on earth would ages more than twin on c right? so then twin on earth's time is greater than twin on c...

you're using the wrong frame of reference.

Originally posted by Adam
5 is D, no doubt. Read it.. What time had elapsed on this (earths clock) when seen from the spaceship. Time is slower on earth, they are asking how much time passed on earth, which has to me more than 10, hence it can only be D.

time is slower on earth, exactly, so less than 10!

 

[freaking_out]

Originally posted by Affinity
...I can bet life on it.

wow, calm down cowboy, its only an hsc exam...

 

[LadyMoon]

Oh the Astronaught thing is scaring me!

 

[failingTheHsc]

ok haha here are my explanations for those who care.

4. i got b but everyone else seemed to got a

r^3/t^2 = r^3/t^2 for x and y since they orbit the same planet??

r^3/tx^2 = (4r)^3/ty^2
...
ty^2/tx^2 =

ok i just realised i forgot to cube the 4. DAMNIT


5. first of all this is isnt an inertial frame of reference since the spaceship is accelerating away from earth. however he is travelling at high speeds so time on his spaceship slows down relative to earth. therefor earth times goes faster than on the spaceship. therefor the clock on earth > 10 years, d

 

[failingTheHsc]

14/15
cuz one of those silly stupid fukn maths mistakes on 4. argh

 

[walla]

does anyone here actually understand general relativity? i know i've got no idea, except i'm pretty sure that we don't have enough info (eg; nothing about acceleration) to work out the question according to general relativity
and using special relativity, b is correct (dammit put d )

 

[ssssonicyouth]

Originally posted by B.Rabbit
that 25:1 question... Thats so FUCKING STUPID... WHY THE #@%did they state the whole question in primary:secondary then for answer make it secondary to primary ??? WTF is the point seriously... i worked all the shit out and got it wrong by putting 1:25 aswell... thx BOS u dumb fucks test physics not how carefully we examine EACH WORD in a question... BLEED BITCH BLEEEEEED

but people who get high marks become lawyers-- so the ability to be anal retentive is actually quite important

Edit: with the photoelectric question- it seems like most people r putting d- and if the majority of band six people put a wrong answer, then they just go 'oh, the question was messed up' and scrap it. I have a feeling it'd be quite likely with this one.

 

[freaking_out]

Originally posted by ssssonicyouth
but people who get high marks become lawyers-- so the ability to be anal retentive is actually quite important

ya, u don't wanna make that stupid mistake if ur a phycisist.

 

[kouri]

so 4 is a, according to kepler's 3rd law right??

NOOOOOO i put b.