When gravity causes the ball to drop, the knuckle locks closed.
(the knuckle; locks; closed; T:When gravity causes the ball to drop) (the knuckle; closed; T:When gravity causes the ball to drop) (gravity; causes; the ball to drop) Context(gravity causes,List([5, 19))):(the ball; to drop; )
gravity causes,List([5, 19))
the knuckle the knuckle gravity the ball
locks closed causes to drop
closed T:When gravity causes the ball to drop
T:When gravity causes the ball to drop
the ball to drop