Re: [Phys-l] A kinematics question

[Jack Uretsky <jlu@hep.anl.gov>]

Hi all-
	I'm nt qualified to answer the first question.
	Average speed is usually defined as \Delta s/\Delta t; I get about 
6.15 m/s.
	Av. acceleration = \Delta v/\Delta t ;  I get about .114 m/s^{2}
			Regards,
				Jack




On Sat, 28 Jun 2008, Josh GATES wrote:

> Am I crazy, or is this 1-d kinematics question overdefined?
> "A runner runs around a 400-m track in 1 minute, 5 seconds. What was the
> runner's average speed? The runner began the run from a standing start and
> finished the run with a sprint at 20% more than the average speed. What
> was the runner's average acceleration over the entire run?"
>
> Using two different methods, I get two different answers for the
> acceleration.  I suppose that there are a few possibilities:
> - I screwed up!
> - the problem is overdefined
> - the problem's statement is unclear (or unclear to me).
>
> I asked the author of the problem and got an interesting response that
> describes a situation different from the one that I visualize when I read
> it.  Even at that, I'm ot convinced of the explanation, but I'll keep the
> response to myself for the minute.
>
> So... what do you think?
> I will require:
> - a snarky response about how this would be easier if we used bivectors
> - a response with 2.3 x 10^8 references
> - a post about how this problem was much better in the good old days with
> a cryptic PS.
>
> :)
>
> jg
>
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