Cue Sports Techniques - Throw

"Throw" refers to an object ball's motion away from the impact line due to relative sideways sliding motion between the cue ball and object ball caused by sidespin or a cut angle.

When a ball with english (sidespin) on it hits an object ball with a degree of fullness, the object ball will be "thrown" in the opposite direction of the side of the cue ball the english was applied. Thus, a cue ball with left hand english on it will "throw" a hit object ball to the right.

This effect is sometimes overarchingly referred to as "the gear system;" so-called because the interaction of the cogwork gears of a clock — each circular gear is interlocked with an abutting circular gear and each spins in the opposite direction of its neighbor in a series. English on the cue ball can cause a very similar effect. If the cue ball with left hand english in the preceding scenario contacts an object ball relatively full and that object ball is frozen to another, the first object ball is thrown to the right and the second to the left, exactly as the name implies.

Throw is also imparted to a ball by collision from a cue ball with no english on it through friction. This is sometimes called "collision-induced throw". The direction of the throw depends entirely on the direction the cue ball hits the object ball from. Unlike throw caused by spin, friction from a collision induced throw "pushes" the cue ball in the same direction as the cue ball was traveling before impact. Thus, a cue ball traveling from the left will cause an impacted object ball to be thrown slightly to the left of the natural angle it would otherwise be sent.

Both varieties of throw are highly influenced by speed. Generally, the less momentum the cue ball possesses at the time of impact, the more that throw will affect the object ball's resultant path of travel.