Paper and pen challenge

Main Question or Discussion Point

Hello ! My friend challenged me to remove a sheet that is under a standing pen, without the pen falling. I can only use 2 finger and i can only touch the paper. Do you know a way to do this ? (he said that I have to use physics)

Related Other Physics Topics News on Phys.org
turbo
Gold Member
What's the time-factor? If no time is specified and you remove the paper and the pen subsequently falls (even a fraction of a second later) you have done what was required.

The pen is supposed to stay standing.

QuantumPion
Gold Member
Did he give you a precise definition of "remove"?

Got a match?

There's a good chance fire won't solve this problem. If the pen conducts heat well enough, it might prevent the paper around it from burning by conducting the necessary heat away from it.

Is this somehow similar to the "Cheers!" episode in which Norm puts a hat over a mug of beer and bets Cliff he can drink the beer without removing the hat. After Cliff accepts the bet, Norm gets under the bar and makes sucking noises like he's drinking the beer. Cliff says, "You didn't drink the beer." and lifts up the hat. Immediately Norm grabs the beer and drinks it.

Can someone else hold the pen while you remove the paper?

Danger
Gold Member
How on Earth do you get a pen to stand up in the first place?

How on Earth do you get a pen to stand up in the first place?
For a minute there I thought I was the only idiot who couldn't picture this!

QuantumPion
Gold Member
There's a good chance fire won't solve this problem. If the pen conducts heat well enough, it might prevent the paper around it from burning by conducting the necessary heat away from it.

For a minute there I thought I was the only idiot who couldn't picture this!
I assume the pen has a cap with a flat surface.

turbo
Gold Member
If the paper is a slippery playing card overhanging the edge of a table and you are able to give it a very quick snap, who knows? The more massive the pen and the larger the cap, the easier this might be.

Make some magic motion with your hands around the pen. Then tell your friend the paper around the pen is gone and the pen is standing on the table. He won't believe you and lift up the pen. Then you grab the paper. Done! :P

The pen is supposed to stay standing.
If you stand a pen on its point, it will fall over in about 15 seconds, due to the Heisenberg Uncertainty Principle, if I recall correctly the standing pencil problem in my QM course..

DaveC426913
Gold Member
Make some magic motion with your hands around the pen. Then tell your friend the paper around the pen is gone and the pen is standing on the table. He won't believe you and lift up the pen. Then you grab the paper. Done! :P
This is actually a perfectly valid solution.

DaveC426913
Gold Member
Leave an edge of the paper hanging over the edge of the table.
Grab the overhanging edge in one hand.
Use your other hand to "chop" the paper between your hand and the table, pulling the paper out so fast that the pen stays stading.

i dont think you just have to use physics for this, but you can use semantics. stand the pen on a tabletop. place the sheet of paper on the floor 'under the standing pen'.. then remove the sheet of paper. mission accomplished, the pen is still standing.

DaveC426913
Gold Member
i dont think you just have to use physics for this, but you can use semantics. stand the pen on a tabletop. place the sheet of paper on the floor 'under the standing pen'.. then remove the sheet of paper. mission accomplished, the pen is still standing.
Good one. Though it depends on who gets to set the demo up. If he'll grant you the privilege then you can rig it that way.

But if there were money riding on it I doubt he'd let you do the setup.