Pwned!! (1 Viewer)

toknblackguy

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i sent the question to a harvard professor and this is the transcript of the emails (you might wannar ead from the bottom up)

Jason,

This is a good example of what's wrong with multiple choice exams. In the
spaceship looking back at the Earth you'll just see the relativisitic
Doppler shift which is sqrt((1+v/c)/(1-v/c)) = 3, so your answer should
have been 3.33 years which was not one of the choices.

--Edward L. (Ned) Wright, Professor of Physics and Astronomy
310-825-5755, FAX: 310-206-2096, www.astro.ucla.edu/~wright/intro.html
Mail: UCLA Astronomy, PO Box 951562, Los Angeles CA 90095-1562
FedEx: Math Sciences 8951, UCLA Astronomy, 405 Hilgard Ave, LA CA 90024

On Sun, 2 Nov 2003, Jason Tokn wrote:

>
>hahahaha...umm...this was a secondary school question, and i think the
>question is just asking that at the time of arrival at the star, the onboard
>clock showed 10 years. so if the astronaut was to somehow view the earth's
>clock from his location, at the exact time of arrival, what time would he
>see...i hope you understand what i'm saying. as for the spatially separated
>but simultultenous events part, i thought that the events would not be
>viewed as simultenous from the two different frames of reference. anyway,
>this is far outside the scope of the question and our learning. so if
>possible, could you now answer the question?
>
>if not, nevermind, as perhaps this question would be better understood by my
>school teacher.
>thanks
>
>>From: Ned Wright <wright@astro.UCLA.EDU>
>>To: Jason Tokn <tokn_black_guy@hotmail.com>
>>Subject: Re: Time Dilation.
>>Date: Sat, 1 Nov 2003 08:10:28 -0800 (PST)
>>
>>Jason,
>>
>>How do you define "when" in
>> > when seen from the astronauts's spaceship
>>
>>In working out the answer to this question you will get the answer.
>>How do you define spatially separated but simultaneous events?
>>
>>--Edward L. (Ned) Wright, Professor of Physics and Astronomy
>> 310-825-5755, FAX: 310-206-2096, www.astro.ucla.edu/~wright/intro.html
>> Mail: UCLA Astronomy, PO Box 951562, Los Angeles CA 90095-1562
>> FedEx: Math Sciences 8951, UCLA Astronomy, 405 Hilgard Ave, LA CA 90024
>>
>>On Sat, 1 Nov 2003, Jason Tokn wrote:
>>
>> >hi. i'm a year 12 student who just sat the hsc in australia, and i have a
>> >question regarding the relativity of time.
>> >the multiple chouice question 5
>> >an astronaut set out in a spaceship from earth orbit to travel to a
>>distant
>> >star in our galaxy. the spaceship travelled at 0.8 c. when the spaceship
>> >reached the star the on board clock showed the astronaut that the journey
>> >took 10 years.
>> >an identical clock remained on earth. what time in eyars had elapsed on
>>this
>> >clock when seen from the astronauts's spaceship?
>> >A 3.76
>> >b 6
>> >c 10
>> >d 16.7
>> >
 

walla

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hahaahh that's the funniest thing i've ever heard
 

...

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yea..the Hertz one too..

hertz didn't state anything with photoelectric!!

but he did found out something fishy bout it...
 

Dave_B

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does sqrt((1+v/c)/(1-v/c)) = the formula we had..?

tV = tO sqrt(1-(v/c)^2)

i think the prof is using a different formula?
 

Bannanafish

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Originally posted by Dave_B
does sqrt((1+v/c)/(1-v/c)) = the formula we had..?

tV = tO sqrt(1-(v/c)^2)

i think the prof is using a different formula?

yes he said he's using the dopler shift formula
 
N

ND

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Originally posted by Dave_B
does sqrt((1+v/c)/(1-v/c)) = the formula we had..?

tV = tO sqrt(1-(v/c)^2)

i think the prof is using a different formula?
I take it you don't do maths? :p It doesn't take long to see that it's not the same.
 

Dave_B

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actually ext1, but i've made an effort to forget all of it....

i couldn't be bothered playing around with it until i got something resmbling the other one :)

plus i've gotta cram for economics and ext history - same day exams suck
 
N

ND

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Originally posted by Dave_B
actually ext1, but i've made an effort to forget all of it....

i couldn't be bothered playing around with it until i got something resmbling the other one :)
Heheh, yeh i can barely remember the name of Harwood's poems... So glad to get that crap out of my head.
 

Dave_B

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think harwood is bad....

we had Ted Hughes.... argh, that was awful.
 

Affinity

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Hey, the professor should also consider the effects of the gravitational field of the sun, and the earth on time.
 

Affinity

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Also, in special relativity, difference in time not only depends on the relative speeds of 2 frames, it also depends on the position in the frame

it's always taught that:

t' = t/(1-v^2/c^2)^(-1/2)

it's actually

t' = (t-vx/c^2)/(1-v^2/c^2)^(-1/2)

and .. we haven't taken that into consideration.
 

Affinity

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BOS bashing is more interesting and fun thatn studying for chemistry
 

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