Did Anyone Get Confused By The Wording Of The Time Dilation Question (2 Viewers)

[Rahul]

think, "the moving clock will slow down'. but first you have to choose the frame of reference that is moving, like affinity said

 

[Dash]

Originally posted by Affinity
not everyone else, I am with you guys, I am your friend

First thing to do in relativity is to choose the frame of reference. and in this case, it's the spaceship's frame that is considered stationary and the earth's frame is 'moving'

so it's B

It's B woo hooo!!!
If Affinity if wrong, im getting it wrong with her

 

[~TeLEpAtHeTiC~]

hmm after reading that..
in understanding relativity the syllabus doesn't expect us to understand special relativity and the 'twin paradox'
only einsitens defination of special relativity..dont recall it asking us to go into detail and its consequences... although i did learn twin paradox
so essntially becuase it was a multi chioce question is wasn't asking a great deal... so as i took it.. it was just basic substitution itno the formula giving (D) as the answer
ok..is my logic
(a) right
(b) wrong
(c) confused
(d) wheres my pants?

good luck everyone

 

[juber]

See the thing is that they will DEFINATELY, without a doubt accept B as a correct answer...

But the thing to put forward now is whether they may also accept D.

I think that if the marking board can get a consensus that it should only be B based on the fact that it is the frame of reference and not the observer on earth, then they wont accept D, but the thing is that its a fairly difficult concept to get your head around, and most physics teachers / markers probably would make the same mistake as us, so there might be arguements put forward by stubborn physics teachers than D should be accepted for whatever reason.

I agree now that by the nature of the question the answer is B and only B but lets hope that there are some arguements in the marking center and they decide to comprimise and accept both (fingers crossed cos I put D! lol)

 

[toknblackguy]

hahaha
i knew it
it's definitley B!!!

 

[toknblackguy]

i'm hoping they only accept b
i need every mark over u guys

hahaha
actually i think i did pretty damn good
i found the test quite easy
although it seems that i didn't write about enough for the last Q2Q question 8
i talked about how in a controlled and uncontrolled there was the reactor fuel, control rods, moderators, coolant and starter thing of course, and hiow they differ between a bomb and reactor

all up it only took about 2,.5 pages

 

[walla]

fuck
are there really moderators in a bomb? and control rods and stuff?

 

[Adam]

Alrighty o, here we go. Firstly, the earth is not moving, the spaceship is, since when does the earth move relative to a spaceship, looking at it that way just overcomplicates things.

http://members.optusnet.com.au/ajpodnar/8.gif

To explain it, I did a little crappy drawing, it can not be B!!!. I would bet a large sum of money on it. You see, the people on earth have aged more, therefore there has been a longer period of time as compared to the spaceship, therefore it can't be anything but D, thankyou!

 

[walla]

adam its not "one moving one not moving"
they are both moving relative to each other
there is no such thing as "absolutely stationary"

 

[Adam]

Yeah, well duh, Einstein said that, but in this situation, the earth is a stationary observer and the spaceship is an intertial reference frame. The question is not worded in such a way that in any way suggests that the earth is moving in any direction at any speed, your argument is void.

 

[juber]

Yeah.

Its all got to do with the "frame of reference"

The "frame of reference" in this case is the spaceship which needs to be seen as the Tv (time of the observer). To is the "real" time experienced within the "moving" body. In this case, because you are looking at it "from" the spacecraft, Tv is to be viewed as 10. To is the variable that we dont know.

This gives an answer that is less than 10 so it cannot be D.

First thing to remember about special relativity - forget all logic. Dont try to comprehend it cos youd probably get your brain tangled up in doing so. Saying things like "but the time goes slower in the spaceship" is irrelevant since that is when viewed from the frame of reference of an observer on earth. Time does not go slower at all for the people inside the spaceshit, it all depends on the frame of reference, and in this case, the frame of reference in the spaceship which as crazy as it may sound, means that it is shorter - i.e. B.

It is also worth noting that 16.7 was the only answer more than 10 which indicates that there was no distractor in the question should it be >10. There was howevor a distractor for <10, so it seems clear the the examiners had clearly intended this to be a trick question.

 

[dnt stop runnin]

everybody......picture it in terms of the twin paradox.....the answer has to be 16.7,,,,,coz from the astronauts frame of reference.....time will dilate, therefore, the earth clock will be greater than 10.......thats my logic......i cant c it in any way possible how it is B

 

[~TeLEpAtHeTiC~]

i'm oh so lost here
someone got a rope :S

 

[NSBHSchoolie]

dnt stop has it right...

Coz if you think about it, the earth is moving away at 0.8c as well. Therefore observers from BOTH frames see things slower in the other frame of reference.

The question was what time had elapsed on the Earth clock as seen by the astronaut. So the answer must be D becuase the astronaut saw the Earth time slow down.

However this simply uncovers even more BOS inadequacies, as how could he even see the clock? Even if he could somehow see the clock, then additional time would have to be taken into account for the time the light travelling from the clock to the spaceship.

BOS get your facts straight and make physics physics and english english. They are completely different subjects and should be kept so.

 

[Adam]

Originally posted by juber
the examiners had clearly intended this to be a trick question.

Nope. The examiners never trick you, that is a policy of setting an examination, whatever 'seems' right is right.

With all that said and done, it should have been an easy question, but their wording was absolute shit and left a lot to be desired, and as such overcomplicated the question.

I still stand by D, never in any question in any textbook has a sitution been brought up in which a planet is moving and the spaceship is standing still (relatively), so it just doesn't make sense to all of a sudden put that kind of a question into it.

 

[walla]

adam....they are both inertial frames of reference. yes the spaceship is moving and the earth is standing still from earth's reference. but the question asks what the spaceship would see, so you have to consider from the spaceship's frame of reference, ie; the spaceship is stationary and the earth is moving.

 

[Adam]

Yes but its asking how long has passed on earth compared to the clock on the spaceship, and that definitely can not be less time than what has passed on the ship.

As for both seeing each other age more, this is only in special relativity. In general relativity (which we are talking about here, because there is no mention of any sort of acceleration, he is an inertial frame of reference), the person who goes into space ages less, therefore more time has passed on earth.

 

[walla]

"As for both seeing each other age more, this is only in special relativity. In general relativity (which we are talking about here, because there is no mention of any sort of acceleration, he is an inertial frame of reference),"

i rest my case
go and read a textbook or something

 

[freaking_out]

Originally posted by walla
"As for both seeing each other age more, this is only in special relativity. In general relativity (which we are talking about here, because there is no mention of any sort of acceleration, he is an inertial frame of reference),"

i rest my case
go and read a textbook or something

lol, general relativity is waaay beyond the course and our abilities!!!! and yeah, it also actually deals with acceleration!!!

 

[Adam]

Oh yeah, its that easy, just say its B and it will be.

I have yet to see one good explanation on why it is B. I have read much about the reason of it being D.