Our little Newton's cradle is a favourite in the Studio;
Newtons' Third Law:
"For every action there is an equal and opposite reaction."
Newton's cradle aptly demonstrates this law as the balls react to being hit by one another.
Simply pull back any number of balls from one side or the other and watch the reaction it has to balls on the other side.
Dimensions 7.5 x 9 x 2.5 cm