All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Shapes > Geometry
On The Edge (Posted on 2004-10-24) Difficulty: 3 of 5
Consider a round jar with no lid. The radius of the opening in the jar is 10. A coin (with a radius R < 10) can be placed flat on the edge of the jar without falling. The coin can be placed such that its center is on the rim of the jar, or it can be moved toward the center of the jar.

What is R, when the coin is as close to the center of the jar as possible without falling in, and the inside edge of the coin is at the center of the jar's opening?

See The Solution Submitted by Brian Smith    
Rating: 3.0000 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Maybe Solution | Comment 3 of 7 |

I am assuming that the coin will tip-in if the  center of gravity is on the "inside" of the two intersection points of the coin's edge and the jar's edge. Thus the closest balance occurs when the coin's center is on the chord between the two intersection points.

A quick calculation on the resulting diagram gives a coin radius of 52. Yes?


  Posted by owl on 2004-10-24 15:58:03
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (12)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information