Ok, a bit of a mind bender. I heard it at Denny's, so don't blame me... please?

You're in a room. It's 8'x8', and in the center there is a pipe sticking out of the floor. The pipe extends 15" below the ground and 10" above. It is just wide enough for a ping pong ball to fit inside with a millimeter on each side. You have at your disposal: a paperclip, a mirror, and a three foot length of strong thin string. How do you get the ball out?

Out of the room, or out of the pipe?

If you're trying to get the ping pong ball out of the room, I'd try using the door. Assuming there is one.

Maybe it's just me. I can never remember a time when I intended to go to Dennys.

I've certainly ended up there, but that's really a different story entirely.

Do not try to get the ball out. That's impossible. Instead, only try to realize the truth.

There is no ball.

Then you'll see that it is not the ball that gets out; it is only yourself.

In Response to zamphir (#821):

Long ago, I liked Denny's. I think the food's gone downhill there, though. In part, also, I'm just burned out on it.

See, back in college, Denny's was one of a couple places that was open all night. It was the closest such place to the dorm, and until my senior year (when Steak 'n' Shake finally went 24-hour) it was the only place where everyone could find something they'd eat. So when the dorm had "unplanned firedrills", or when we were up all night studying for finals, we'd go to Denny's, eat, study, and play cards.

Eventually they stopped letting us study or play cards there. Nation-wide policy change they told us. Feh. We'd still go there from time to time, but usually only after some serious drinking.

In Response to mea37 (#824):

I used to think that Denny's was sort of like McDonald's, in that the quality (such as it is) would be reliably the same wherever you go. Then I ate at the Denny's across the street from the UNM [unm.edu] campus in Albuquerque. Oh, my sweet lord, how disgusting and pathetic. It was like the worst diner you've ever been in, multiplied by apathy and a complete lack of anything resembling knowledge of cooking.

Anyway, from the Department of Stupid Nationwide Policy Changes, they also now refuse to cook burgers less than medium-well, or eggs less than over-hard. Health risks, don't you know, and they don't want to get sued if you catch E. coli from a medium-rare burger. They won't even consider keeping waivers on hand that you can sign in order to get your burger cooked that way. Far as I'm concerned, that's more than enough reason to stay away from Denny's.

Now, as far as this ball-in-a-pipe goes, I haven't the foggiest idea. I hope you post the solution before we hunt you down in a huge, paperclip-wielding angry mob.

Beeeej

Blow.

Seriously. Blowing into the pipe will cause a slight pressure differential to build up. The ball will rise to the top and you can grab it.

Damn librarians.

In Response to snookles (#865):

Shouldn't that be blowing across the top of the pipe? Not into it?

well, ping pong balls float don't they? all you would need was lots of beer and a full bladder. i think you can figure out the next step.