toknblackguy
Member
- Joined
- Nov 1, 2003
- Messages
- 299
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- HSC
- 2003
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
>> >
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
>> >
