Science Projects And Inventions

YOU NEED:

• A playing card

Surreptitiously, bend a card ever so lightly as shown above. The back becomes convex as in the illustration. Between the tips of your right thumb and middle finger hold the card with rear side up. Your thumb should be on corner X and the middle finger ought to be on Y.

Ever so slightly ease the pressure on the corners until the cards are about to drop to the floor. While the card is almost about to fall on the floor it will also slowly turn in your hand and will be facing up.

For it to rotate you will need a bit of practice to hold the card lightly. The card's movement is ghostly.

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HOW DOES IT WORK?

The convex shape raises the centre of gravity of the card. The card rotates because the centre always seeks its lower point.