Juggling isn't about catching; it's about throwing. To the uninitiated, it looks like a chaotic flurry of hands. To the juggler, it is a predictable cycle of parabolas.
This guide explores the mental model required to maintain the "Cascade"—the fundamental three-ball pattern. We will transition from the physics of a single arc to the algorithmic logic of keeping three objects aloft.
A ball thrown upward follows a parabolic arc defined by gravity. Beginners often track the ball with their whole head, creating dizziness. Experienced jugglers do something subtle: they look at the top.
At the very top of the arc—the vertex—vertical velocity momentarily hits zero. The ball "hangs" in the air. This is the only moment the ball is predictable.
Adjust the throw force above. Notice how the green velocity arrow shrinks? At the peak, vertical speed vanishes. That hesitation is your cue to throw the next ball.
Beginners often fall into the trap of the "Shower" pattern—passing the ball horizontally from one hand to the other. This is inefficient and requires fast hands.
The correct method is the Cascade. It creates an "X" (or figure-8) in the air. You must throw the second ball toward the inside of the incoming ball, exactly when the first reaches its peak.
In Shower mode, notice the red horizontal pass. This is the "Panic Zone." In Cascade mode, notice the crossing point. The balls never collide because they occupy the intersection at different times.
With three balls, the logic is strict: When a ball in the air hits its peak, the hand holding two balls must throw.
Below is a simulation with "Moon Gravity" to help you learn the rhythm. You act as the brain. Click THROW to launch a ball.
The goal is not to catch, but to empty your hand before the incoming ball lands. If you click too late, your hand is full when the ball arrives (Game Over). If you click too early, you break the rhythm.
How do you buy yourself more time to think? You throw higher. But physics demands a tax. The relationship between time aloft (t) and height (h) is a square root function:
To double your flight time, you must quadruple your height. This makes high juggling exponentially harder to control.
Use the sliders to see how Height and Gravity affect the cycle time. On "Jupiter" (high gravity), the rhythm becomes impossibly fast.