An interactive study in friction, physics, and visual perception.
Magic relies on the gap between what you see and what actually happens. In the "Slip Force," the goal is to make a spectator think they have cut to a random card, while actually forcing the top card of the deck upon them.
Click "Riffle" to begin the trick.
To understand the Slip Force, we must look at the deck from the side. The secret lies in the fingers of the hand holding the deck.
At 0% completion.
The Secret: As the right hand pulls the top packet away (moving right), the left fingers apply pressure to the top card (Red). This friction keeps the top card in place, causing it to fall onto the bottom packet.
Why does the top card stay behind? It's a battle of friction. The friction between your stationary fingers and the card (\(F_{finger}\)) must be greater than the friction between the cards (\(F_{cards}\)) dragging it away.
Success. The card stays put.
The mechanism is obvious in slow motion. To sell the illusion, the "Slip" must happen faster than the eye can track (approx 1/10th of a second).
Adjust speed and perform.
By combining the correct finger pressure with a swift motion, the mechanical reality of the slip vanishes, leaving only the illusion of a free choice.