Re: walk to enjoy the rain

[David Bowman <dbowman@TIGER.GEORGETOWNCOLLEGE.EDU>]

Regarding Brian's comment and quibble about my post about the 'walking
in the rain' problem:

> > 2. The vector velocity v of the rain moving with respect to the person is
> >   the vector difference v = v_p - v_r where v_p is the vector velocity
> >   of the running/walking person w.r.t. the ground and v_r is the
> >   (fixed for an assumed monodisperse distribution of rain drops)
> >   terminal velocity of the rain drops w.r.t. the ground....
>
> > David Bowman
>
> This had such clarity that I could follow the development quite well.
>   Even better, David left a little room for quibbling,
> than which there is nothing better.

Thanks for the compliment, yet my re-reading of the above caused me to
discover something *else* to quibble about with my own post.

> To be specific, the person's velocity w.r.t the ground is a modest
> alternating movement. I'm sure David had in mind the person's
> velocity w.r.t his destination?

I assumed the person's destination is at rest w.r.t. the ground, so that
the person's velocity w.r.t. the ground is also his/her velocity w.r.t.
the destination.  It is true that I meant for v_p to be the person's
velocity *averaged* over the steps of the person and that the vertical
amplitude of the oscillatory motions of the steps was quite small
compared to the height of the person.

The new quibble I just noticed (beyond a few of minor typos sprinkled
through the post) was that I got the sign of v wrong.  I wrote that
"The vector velocity v of the rain moving with respect to the person is
the vector difference v = v_p - v_r" when in fact this equation for v
gives the velocity of the person w.r.t. the rain.  The velocity of the
rain w.r.t. the person is -v as defined above.  Fortunately, this sign
error has no effect on the rest of the post or its conclusions.

Btw, note to Brian.  The 'create date' of your post is two days *after*
the 'received date'.  Either you need to check your computer's date or
you have become adept at time travel.

David Bowman
dbowman@georgetowncollege.edu