The objects will not change position from their initial rest positions because the downward force on each side of the pulley (ignoring the weight of the string) is the same and the net force on each side of the pulley is zero. The gravitational attraction is the same on each object. An object remains in constant motion (or at rest) unless a net force greater than zero acts on it. This is Newton’s first law of motion. This series of experiments helps students understand the concepts of force and motion. It includes the Table of Contents and the Index.