In a "minute to win it" game, cards are placed between cups to stack them. (see the picture) The contestant then
pulls the card out in hopes that they will end with a set of stacked cups. Why does this work?
Yank Me!
Minute to Win it
Party Game

It will work as long as the contestant is gentle but quick enough at pulling out the card from in between the stack of cups and it works because the balance is maintained as the card is yanked out from beneath the cups. Since the center of gravity does not shift for the cups, they do not fall off of one another.

Hope that answers the question, have a great day!

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