Sand Pendulum - Pit & Pendulum Garden. Cherry Wood Finish, 15 Inch Great executive stress reliever and conversation piece The Sand Pendulum demonstrates real science as it converts kinetic energy into potential energy gravity creates a different sand sketch each time the pendulum is in motion Each swing of the pendulum will calm and mesmerize you with its rhythmic motion Simply get the pendulum arm moving and watch as gravity creates ever changing geometric patterns from circles and ovals to rectangles and squares