Question On The Physics Of Card Ripping

[Jonathan McMillan]

Hey all,

Hope someone can help me out with a generic description on how cards rip when ripping a deck of cards. I am doing a demonstration at my boys' school and can make up some quazi scientific explantation for force in steel bending, grippers, frying pan rolling etc. but haven't heard much that would be good answers for any questions in regards to the card ripping stunts.

Can anyone help me out, their aiming for me to go in next tuesday.

Thanks

Jon@han

[GarytheDino]

My personal opinion is that too many people toss around numbers that mean nothing already. This is something real you can show them. Lifting a barbell you can state the weight and someone will say someone they know does more because people exagerte the numbers. The bottom line is you can tear a deck and the average person can not.

Edited December 12, 2007 by GarytheDino

[Hazerboy]

Most of these you can relate somehow to torque and friction. A quick search on wikipedia will yield good results. Torque will also work well on cards, as well as friction, i.e. say something like "the frictional force between my hands and the cards must be equal to the amount of force needed to produce enough torque for them to rip." So you have to not only have enough wrist strength to produce the amount of torque needed to rip the cards, but enough finger strength to produce enough frictional force (as the frictional force = the force you're applying x how "grippy" the cards are, might try wiki-ing this also) to hold on to the cards.

As for "how" they actually rip, that depends on how you want to approach an explanation. You could say that the force/torque you're applying on the cards is greater than the molecular forces of the cards, or something like that.

[Jedd Johnson]

You might employ the word sheering, I guess?

[Jonathan McMillan]

Thanks guys it's much appreciated!!!

Jon@han