Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: SR examination question



I second the contextual assumption(s) RT has made -- very likely the question
is a modification of an example in the text, and or follows other similar ones
in the exercises (problem set) and previous exam. question(s). I think most
would interpret it as an SR and not a GR question.

Or have I missed something?

bc



Rick Tarara wrote:

Read the original question again:

Peter and Jane are each wearing a wristwatch with a second hand that takes
one minute to make one complete revolution and Peter is moving at a speed
of 0.9c with respect to Jane. When Peter observes the second hand on his
watch to have made one complete revolution, how many revolutions will Jane
observe the second hand of her watch to have made?

Peter, moving (linearly) at .9c observes 1 minute to have passed. During
the time that Peter's watch has ticked off 1 minute AS OBSERVED BY HIM, how
many minutes does JANE observe (in her frame--assumed to be at rest) to have
ticked off on her watch? That's what the question says to me. Now if you
want to read in complications--both are moving away from each other at .45c
and Peter is reading Jane's watch and Jane is reading Peter's--feel free,
but the question is still clear enough to me with no sexist (or even theist)
overtones. ;-)

Rick

----- Original Message -----
From: "John S. Denker" <jsd@MONMOUTH.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, May 17, 2001 1:17 PM
Subject: Re: SR examination question

Earlier today, someone who remain nameless wrote:
I think it is quite clear what the question intends.
Jane's second hand makes 2.29 revolutions while Peter's makes one.

Ahh, so it is _quite clear_ that Peter's reference frame is preferred.

I know how to explain this:
1) It is obvious that girls can't be scientists.
2) Therefore if we measure something, we must measure it in
Peter's frame, not Jane's frame.
3) Anybody who identifies with Jane (or even gives Jane
equal standing) will have their homework marked wrong.


... and the observation is a 'God's Eye View' as is
often the case when talking about time dilation.

Wow, God prefers Peter, too.