[Phys-l] fun ill-posed questions

[John Denker <jsd@av8n.com>]

On 10/10/2006 06:23 PM, Cliff Parker wrote:
> ....  There is a time and a place for those 
> kinds of questions.

This is getting rather far afield from the request that started the
"Good Questions" thread, but this is a new thread now.  Ill-posed
puzzles can be fun and highly instructive.



I just documented two more fun little puzzles:

*) A Yo-Yo rolls without slipping on the floor.  When I pull the string,
does it roll toward me or away from me?
  http://www.av8n.com/physics/ill-posed.htm#sec-yo-yo

*) You start out at point A. You travel strictly south for one mile. You
then make a 90 degree turn and travel strictly east for one mile. You
then make another 90 degree turn and travel strictly north for one mile.
You find that you have returned to point A.

For simplicity, we approximate the earth’s surface as spherical.

Part 1: Where is point A?

Part 2: How do you know?  Are you absolutely sure you know where
 point A is?  Can you prove it?

  http://www.av8n.com/physics/ill-posed.htm#sec-s-e-n