| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 581.1 | Ho hum.... | FDCV01::LOHMILLER | | Thu Sep 18 1986 12:01 | 2 |
| 30.
|
| 581.2 | re. .1 | THEBUS::KOSTAS | Wisdom is the child of experience. | Sat Sep 20 1986 20:18 | 26 |
|
re. .1
yes,
since I never liked short answers, and I am allways interested
in the method used to get to the solution I will elaborate a little
more than "30."
The problem of the fly and the bicycles is very puzzling if one
starts to reckon the times of the fly's successive trips. But if
we observe that the cyclists approach each other at the rate of
(20 + 25) = 45 miles per hour, we see that it is just one hour
before they meet, and in that time the fly will go just 30 miles.
The problem is easily generalized. If we let a nd b be the rates
of the cyclists, m the original distance, and f the rate of
the fly, the cyclists will meet in m/(a+b) hours, and in that
time the fly will fly a distance of
mf
------- miles
(a+b)
-kgg
|
| 581.3 | How many times does fly change course ? | RAYNAL::OSMAN | and silos to fill before I feep, and silos to fill before I feep | Mon Sep 22 1986 17:25 | 10 |
| For folks like myself, that solved the standard fly-between-bicycles
problem long ago, perhaps the following related problem might be
more challenging:
How many times does the fly (assume length f)change course before
the bicycles are less than or equal to f from each other, i.e.
where the fly presumably gets mashed and the riders are about
to crash, or the riders pass each other.
/Eric
|
| 581.4 | ...and quite a bit of buzzing was heard just before the crash | TSE::FONSECA | Caught peeking under the rug of life... | Thu Sep 25 1986 15:39 | 2 |
| I'm not sure about this, but if this is theoretical fly (no length)
wouldn't the number of direction changes be infinet?
|
| 581.5 | yes | CACHE::MARSHALL | beware the fractal dragon | Thu Sep 25 1986 16:43 | 6 |
|
/
( ___
) ///
/
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| 581.6 | | BEING::POSTPISCHIL | Always mount a scratch monkey. | Thu Sep 25 1986 17:41 | 7 |
| Re .4, .5:
No. The request was for the number of changes until a certain
condition, not until the bicycles meet.
-- edp
|
| 581.7 | Who Needs A Floating Point Hotbox? | DRUMS::FEHSKENS | | Fri Apr 29 1988 16:25 | 15 |
| There's an amusing anecdote about John von Neumann and this puzzle,
related in Goldstein's book about the history of computing (actual
title unreachable just now). In this story it's two trains rather
than two bicycles.
After the problem is posed to him, von Neumann looks up at the ceiling
for a moment and gives the answer. The poser says "Ah, you know
the trick." Von Neumann says "What trick?" "The one that allows
you to avoid summing the infinite series."
To which von Neumann replies, deadpan, "But I *did* sum the infinite
series."
len.
|