Jump to content


Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.

Of course, you can also enjoy our collection of amazing optical illusions and cool math games.

If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.

Thanks and enjoy the Den :-)
Guest Message by DevFuse
 

Photo
* * * * * 1 votes

The clock in the mirror


Best Answer Rainman, 20 February 2014 - 11:35 AM

Spoiler for

Go to the full post


  • Please log in to reply
1 reply to this topic

#1 bonanova

bonanova

    bonanova

  • Moderator
  • PipPipPipPip
  • 5891 posts
  • Gender:Male
  • Location:New York

Posted 20 February 2014 - 10:07 AM

A while ago, BMAD posted a problem about a clock with indistinguishable hour and minute hands and asked at what times of day, between the hours of noon and midnight, it was impossible to unambiguously determine the time. The hands moved continuously.

 

This puzzle asks a related question. At what times of day, between the hours of noon and midnight, is it impossible to distinguish the hands of such a clock from those of its mirror image? Clearly noon is one of these times, but not in general thereafter -- since the clock's hands will move clockwise while the hands of its mirror image will move counterclockwise.


  • -1
The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#2 Rainman

Rainman

    Advanced Member

  • Members
  • PipPipPip
  • 143 posts

Posted 20 February 2014 - 11:35 AM   Best Answer

Spoiler for


  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users