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.)
Some Thoughts Layman speak | Comment 5 of 7 |
the way i would approach this is to imagine a line through the centre of the coin, this line intersects the edge of the coin 180 degrees opposed.

now if both of these point are outside the rim of the jar and the centre is inside, then the coin will balance.

the trick is to find a coin that will balance like in the question when the jar is R10.

I do not have a clue where to go from here, sorry

  Posted by Juggler on 2004-10-24 16:50:09
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (2)
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

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